A recently completed NJDOT research study, Innovative Pothole Repair Materials and Techniques, tested several new techniques and materials that could improve the cost-effectiveness of pothole repairs in New Jersey. Phase I of the research project, led by Professors Hao Wang and Husam Najm of Rutgers University, evaluated new methods for both asphalt and concrete structures. Pothole repair is one of the primary maintenance activities for highway agencies, generating significant costs and resource commitments. Cost-effective pothole repair methods can reduce or eliminate the possibility of re-patching and save future repair costs.
Asphalt Pothole Repair
Asphalt pavement is continuously subjected to vehicular and environmental loading throughout its lifecycle, leading to the inevitable occurrence of distresses such as cracking, rutting, raveling, potholes and so on. Among these distresses, potholes are critical as they can disrupt traffic, impose risks to safety, and cause costly vehicular damage for vehicle operators.
Field repair of pothole using induction heating.
Pothole repair is a primary maintenance activity for highway agencies. Typically, cold mix asphalt is used for emergency repair and hot-mix asphalt (HMA) for traditional repairs. Usual pothole repair methods include throw and go (roll), edge seal, semi-permanent, spray injection, and full depth repair. Among them, throw and go (roll) method using HMA has been adopted by most transportation agencies for surface patching. However, this common practice largely relies on the usage of HMA. Although the quality of the asphalt patch can be ensured, it presents environmental concerns due to the energy consumption and environmental footprint involved in producing new HMA. To mitigate the impact on the environment, reduce cost and conserve energy, recycled asphalt pavement (RAP) has been widely used as a highly desirable material. The addition of recycled asphalt pavement (RAP) in asphalt mixtures can bring numerous economic and environmental advantages.
Infrared heating test was used in asphalt repair method.
This study sought to investigate an innovative approach to pothole repair using HMA with RAP and preheating. The study investigated two aspects: First, the performance of HMA with different RAP contents were evaluated through laboratory tests to select the most appropriate content. Second, the in-site strength of pothole repair was evaluated with field cores to quantify the benefits of repair quality due to recycled material and preheating.
Both microwave heating and infrared heating were tested, with varying results. Microwave heating was able to warm both the surface and internal materials of the pavement, however, its efficiency was low and the rate of temperature increase was insufficient. Conversely, the infrared heating method proved adept at rapidly heating the top edges and bottom surface of the pothole to high temperatures and was used successfully in pothole repair.
Further tests were carried out adding RAP to HMA patching materials. The results showed that there was greater abrasion loss, reduced IDT (indirect tensile strength), and interface shear strength of patching material had less resistance to moisture as RAP content increased. Nonetheless, with the application of preheating, the overall performance of HMA containing 30 percent RAP was satisfactory, proving that it is feasible to use RAP material for pothole repair.
Concrete Pothole Repair
Photos showing condition ratings for concrete repairs.
Similar to asphalt pavement, concrete structures are prone to deterioration due to vehicles and weathering. Cracks can develop which lead to further deterioration due to chloride infiltration. Thus, a good repair is necessary for maintaining concrete structures. An ideal repair material should be easy to work with under different weather conditions, be fast setting, and possess good durability. Rapid-setting cementitious patch repair materials are popular for repairing small concrete damage and providing a functional repair within few hours.
Based on extensive literature research and several NJDOT practices, three formulations were chosen as the best performing candidates. Workability, strength, and restrained shrinkage cracking of the formulations were investigated. The restraint shrinkage test protocol simulated upper and lower limits of restraint that a repair material undergoes in real applications. The repairs were also cast and placed in external environmental conditions to expose them to natural weathering actions. The cracking behavior was evaluated including cracking spacing and maximum crack width
The investigation led to the identification of three formulations that did not crack for a period of 10 months in field exposure to NJ climate conditions. Typically, rapid set formulations do not shrink after 6 months. The formulations that did crack revealed that an addition of 1 percent of PVA fibers could significantly reduce the maximum crack width. The maximum crack widths observed in all the formulations were an order of magnitude less than the maximum allowable crack width specified by NJDOT (1/32″).
Contemplated Legislation
The research projects were completed at a time when pothole repairs have attracted critical attention from motorists and legislators within the state. In the current legislative session (2024-2025), the New Jersey State Senate voted unanimously to advance a bill that is intended to address concerns about pothole damage to roads and bridges in the Garden State.
The NJ Senate bill, S862, would require the state DOT to include information about pothole repair projects and their cost in the annual report. The additional information would include reporting on the number of repair projects going on around the state and their cost. The bill includes a separate provision that would require a lifecycle cost analysis to be conducted. The information would be required to be made available to the public on the NJDOT’s website. An identical bill, A2596, was introduced in the NJ Assembly during the legislative session.
AASHTO Recognition
The research project is not only primed to inform the serious legislative issues being raised in Trenton but was recently recognized by the American Association of State Highway Officials (AASHTO) for its contribution to innovation. Every year, the High Value Research Task Force of AASHTO Research Advisory Committee (RAC) holds a national competition to find “high value” research projects throughout the country. In 2024, the Innovative Pothole Repair Materials and Techniques research project was recognized in the Maintenance, Management, and Prevention supplemental category, as described here.
RESOURCES
Wang, Hao, and Xiao Chen. “Innovative Pothole Repair Materials and Techniques Volume I: Asphalt Pavement.” (2024). Final Report. Retrieved here.
Wang, Hao, and Xiao Chen. Innovative Pothole Repair Materials and Techniques Volume I: Asphalt Pavement. (2024). Technical Brief. Retrieved here.
Najm, Husam, Bala Balaguru, Hao Wang, Hardik Yagnik, and Alissa Persad. “Innovative Pothole Repair Materials and Techniques Volume II: Concrete Structures.” (2024). Final Report. Retrieved here.
Asphalt Pavement Pothole Repair with Recycled Material and Preheating. Presentation at NJDOT Research Showcase by Xiao Chen and Hao Wang. Retrieved here (Presentation) and here (Recording).
Concrete production is energy intensive, and requires materials that are both challenging, and expensive to acquire. Material engineers are seeking alternative materials that are more cost-effective and carbon-friendly, but also operate successfully as road and building material.
We spoke with Alyssa Yvette Sunga, a graduate researcher at Rowan University who won the Best Student Poster Award at NJDOT’s 2023 Research Showcase. Her research, “Properties of Cementitious Materials with Reclaimed Cement,” evaluated the characteristics of cementitious materials mixed with varying percentages of reclaimed cement. Sunga and her fellow researchers examined each mixture’s initial setting time, heat of hydration and compressive strength and compared it against ordinary Portland cement. The purpose: to determine if adding reclaimed cement has any effect on the durability and use of cementitious materials. If there is little to no adverse effect, reclaimed cement may help reduce the need for new materials and can reduce the carbon bi-product of concrete. Dr. Shahriar Abubakri (Shah), Ms. Sunga’s supervisor at Rowan University, also joined us for the interview.
Q. Could you tell us a little bit about your educational and research experience and how you got where you are now as a graduate research fellow at Rowan?
A. I’m an international student from the Philippines. I graduated from the University of the Philippines – Los Banos in 2017 with a Bachelor of Science in Civil Engineering. After that, I worked in industry from 2018 to 2022. My former undergraduate professors, who were graduate students here [at Rowan], reached out to me asking if I was interested in pursuing graduate studies. I applied and began my Master’s in Civil Engineering in January 2023.
Q. What interested you about researching the properties of reclaimed cement? Do you hope to continue research in pavement materiality?
A. The environmental impact of reclaimed materials like cement is interesting to me. Cement production is a significant contributor to carbon emissions, so finding ways to reuse it is essential. Additionally, reclaimed cement presents unique challenges and opportunities in terms of material properties, durability, and performance.
So, in a way, we’re helping produce less carbon emissions; that’s what interested me about this study.
I’m currently working on a lot of different concrete projects. We’re hoping to develop more efficient construction approaches, but I also aim to contribute to the development of innovative techniques and solutions that will optimize reclaimed materials in construction projects. We also aspire to collaborate with industry partners and government organizations, so that we can implement these sustainable practices on a full-scale project in the future.
Alyssa Sunga received the Best Poster Award for Student Research At the 25th Annual NJDOT Research Showcase in October 2023.
Q. Was there anything particularly noteworthy or surprising to you discovered from this research?
A. Yes, there’s potential for reclaimed cement and enhancing the performance of unsustainable construction materials. We did not expect that we could use it as a replacement cement or as a supplementary cementitious material. Through various experiments, we found that using this reclaimed cement or incorporating it in cementitious mixtures resulted in comparable properties such as durability, strength, and workability.
Q. Your research looked at cement paste and mortar specimens incorporated with up to 20% Reclaimed Cement and found no significant difference for the flow measurement and setting time. Should further research be done with higher percentages of reclaimed cement? Why did your research cap it at 20%?
A. We’re planning to do further research on larger amounts of reclaimed cement. We just used 20% as a cap to get a general idea of the effect of partially replacing ordinary Portland cement with reclaimed cement. Now that our research with 20% is showing good results, we plan on doing tests with higher percentages in the future.
Q. Your research found that cement paste specimens with up to 20% Reclaimed Cement (RC) saw a 4% reduction in compressive strength after 90 days. What does this mean for applicability (i.e. is 4% a significant reduction? does this make cement paste with 20% RC not suitable for pavement?)
A. A 4% reduction may seem small, but it must still be taken into consideration. However, as long as the strength is within a recommended range, then it is suitable for pavement applications.
Q. Is there a percentage of reclaimed cement that is most likely not suitable for pavement?
A. Alyssa: My advisor would like to jump in to answer that.
Shah: The acceptable percentage of reduction in concrete strength depends on the specific application and the assumptions made by the designer. For instance, practical standards like the American Concrete Institute (ACI 301.1.6.6) typically require that the average strength of three samples meets or exceeds the specified compressive strength. Additionally, each individual sample within this set should not fall below 500 psi of the designed strength. It’s important to note that concrete’s compressive strength can vary widely, ranging from 2500 psi to 5000 psi, and even higher in residential and commercial structures. Some applications may require strengths exceeding 10,000 psi. So, in cases where the required strength aligns with the design strength, even higher reductions may be acceptable.
Q. Mortar specimens with 20% RC had a different result and surpassed the strength after 28 days. Why do you think this was a different result from cement paste specimens? What does this mean for applicability?
A. This difference in result may be due to different factors, but mortar differs from cement paste due to the additional materials like sand. So, this can influence the hydration and the strength development, but we still need to do further research to understand the long-term performance and durability or the effect of adding different materials to the cementitious materials.
We still must do further research to see the effects of adding different materials like sand and gravel to cement paste. If we’re going to use it in concrete, that’s another additional material like an aggregate. It’s just a matter of the specific materials. There are a lot of factors — like the temperature where you make your specimens. So, it’s always just trial and error. There’s no trend to it really.
Q. Your poster suggests that incorporating up to 20% RC has some promising benefits including reducing carbon emissions. What are some of the other benefits?
A. Incorporating the 20% RC will help mitigate supply shortages because we’re able to provide an alternative source of material instead of just using cement. It also promotes eco-friendly construction practices, contributing to sustainable transportation infrastructure, and research on reclaimed cement enables ongoing enhancements in material performance and construction methods.
Q. You have mentioned throughout this interview where there’s a need for more research. Can you describe some specific things that you would really like to research about incorporating reclaimed cement into cementitious materials?
A. The most important part of this research is determining what is the optimal mix proportions to use and then studying the effects on fresh properties and assessing the long-term durability like compressive strength, the tensile strength. These investigations are crucial for understanding the full potential of reclaimed cement in construction. Personally, I’m deeply interested in exploring these research areas further.
Q. What kind of impact do you hope this research will have on material selection by transportation agencies?
A. I hope this research convinces transportation agencies to use reclaimed cement in pavements. It’s sustainable, cost effective and performs well — aligning with transportation agencies’ goals and standards. This could lead to a greener and more resilient transportation infrastructure.
Resources
Sunga, A., Abubakri, S., Lomboy, G., Mantawy, I. (2023). “Properties of Cementitious Materials with Reclaimed Cement”. Rowan University Center for Research & Education in Advanced Transportation Engineering Systems. Poster.
Biometric sensors have long been used in cognitive psychology to measure the stress-level of individuals. These sensors can measure a variety of human behaviors that translate as stress: the movement of eyes, stress-induced sweat, and heart rate variability. Recently, this research strategy has moved beyond psychology and into disciplines like transportation planning, to provide an alternative approach to researching micromobility and stress.
We spoke with Dr. Wenwen Zhang, associate professor at the Edward J. Bloustein School of Planning and Public Policy at Rutgers University, about her experience learning about and using biometrics for a micromobility study. Dr. Zhang’s research, “Rider-Centric Approach to Micromobility Safety” examines the stress levels of micromobility users as they transverse a varied path through an urban space.
Q. How is your research funded?
A. Funding comes from multiple sources. The first source is a seed grant from the Rutgers Research Council which supports an interdisciplinary pilot project. Through this grant, we purchased biometric sensors and hired students to conduct a literature review and develop a research design. We also processed the collected pilot data and paid for participation incentives under this funding. I presented preliminary findings from this study, Rider-Centric Approach to Micromobility Safety, at the 2023 NJDOT Research Showcase. At the time that I presented it, I had 24 samples. The presentation ended up inspiring several people who attended the Research Showcase to volunteer as participants—which increased the sample size to 30.
Our other source of funding came from an external grant from the C2Smart University Transportation Center (UTC) at NYU. We used this resource to support obtaining additional stress sensors, data analysis, cleaning, preprocessing, and modeling, as well as collecting more sample data for the E-scooter and bicycle experiments.
Q. How did you get interested in using biometrics sensors (e.g., eye tracking glasses, galvanic skin sensor, heart rate monitors) to study micromobility safety? How does this research differ from your past work?
A. Before I used biometric sensors, most of my work used passive travel behavior data. For example, to determine the revealed preferences of mode and route choices and risk factors, we used travel trajectory or existing crash big data to develop statistical models. I have found that the entire process is very passive, especially since we only explore risk factors after traffic accidents. It’s surprising that in the research field today we know so little about how human beings actually navigate urban environments while using different travel modes and how it relates to perceived safety. I wanted to explore questions like what is their gaze behavior? How do they feel while they travel using different modes? How do they feel traveling on roads with different design features and how is that going to influence their travel satisfaction or experience overall?
Dr. Robert Noland, Distinguished Professor at the Rutgers Bloustein School, suggested I investigate the use of biometrics in planning studies. As I dug more into the literature, I realized that biometrics in transportation is a very fascinating topic that I wanted to get into. Once I did experiments in the field, I realized that I really enjoyed talking with different people about how they perceive the built environment while they travel. Biometrics provide richer data compared with revealed preference data that I used to work with.
Q. In your research, you noticed that some corridors were more stress-inducing (according to biometric sensors) than expected, despite properly designed safety infrastructure. How do you think this discovery may affect how planners and engineers look at urban road design and micromobility safety?
A. This study collected one-time cross-sectional data. We asked people to walk around an area and tell us whether they feel stressed or not. If they are feeling stress, even in the presence of a safety improvement, it does not necessarily mean that the implemented safety design is not working. For example, in New Brunswick, we observed that a lot of people found it stress-inducing to cross Livingston Avenue, although it has been the subject of a road diet and has several pedestrian safety features incorporated into the new design. While outside our scope of research, one way to understand the impact of the safety infrastructure would be to conduct a “before” and “after” study. This leaves an opportunity for more research, to see how effective the pedestrian-only infrastructure is in reducing stress level. Potentially, it can provide evidence to support pedestrian-only design. Biometric sensors used in a “before and after” study can help us to answer which infrastructure is more preferred.
Q. You are in the process of collecting data for cyclists and e-scooters using the same method, what are your principal objectives in addressing this segment? Do you expect the results to be different?
Dr. Zhang conducted one pilot e-scooter experiment at Asbury Park, NJ in 2022 to test out the devices and examine how to set up research experiments. She equipped the e-scooter rider, Dr. Hannah Younes, post-doc researcher at the Rutgers Bloustein School, with an eye tracking glass, a GSR sensor on the hand, and a 360-degree camera on top of the helmet.
A. Yes, absolutely, different travel modes will likely alter a person’s expectation for a safe travel environment. For example, we noticed a big difference in the enjoyment of pedestrians and e-scooters on the same path through a park. We had thought that the e-scooter users would enjoy the ride as the pedestrians had, however, the pavement was too rough for the small wheels of the e-scooters. Although the park was walking-friendly, it was not friendly for e-scooters. This shows that each of these micromobility modes needs different kinds of support to feel safe and comfortable.
Q. What are the limitations to this study? Do you have plans for future research to address this? How would you like to expand your research in this topic?
A. Each of the biometric sensors has limitations. For example, eye trackers face some difficulty when identifying the pupils of a participant in direct sunlight. As a result, the eye tracker renders a low eye tracking rate. Eye trackers also work better with darker eyes as the eye movements are more readily recognized. The eye trackers, kept on glasses, also restrict individuals who wear glasses from participating. The unfortunate result of this is that it often excludes a lot of senior people from the experiment. This issue may be alleviated as we are obtaining additional funding to obtain prescription lenses for eye trackers.
GSR sensors use low voltage on skin to measure skin conductivity, which may interfere with electric health devices. This limits individuals from participating if they have an electric health device like a pacemaker on or in their body. We purposefully excluded this population from participating to align with IRB (Institutional Review Board) protocol and to mitigate any risks.
Another limitation of the study is that we must collect sample data one by one, which is a time-consuming process. We can only collect a very small sample compared to a traditional statistical model kind of study, which may have access to thousands of records in the sample. From our literature review, biometrics sensor studies typically involve 20 to 30 participants, but for each participant we have a very rich dataset. For each participating volunteer, we end up with over one gigabyte of data. The limited number of participants may make it harder to generalize results to the entire population, and people may question the results applicability. In some ways this data is similar to the results of qualitative studies, where we have richer information but small sample size, rendering some generalizability issues.
Feelings of safety were measured using the traditional self-report survey as well as biometric trackers like Heart Rate Trackers, Eye trackers and GSR (pictured above).
Q. What challenges have you found in working with biometrics sensors, or in the interpretation of output measures?
A. Theeye tracker and heart rate measures are reliable, but some biometrics have posed challenges. The GSR (galvanic skin response sensor), which tests your sweat level, is very sensitive to humidity and time of the day. The sensor also picks up on sweat resulting from physical exertion, making it difficult to distinguish between stress-induced sweat and physical sweat.
Interpretation of output measures for this metric requires data cleaning and processing to eliminate the effect of sweating from physical exertion. We try to decompose the data to separate the emotional peak from the sweating caused by physical activity using various algorithms. We are still underway testing out different algorithms to clean up the data. So far, we have found that GSR data are very real-time in nature and a good indicator for stress level but are very noisy data and requires some manual processing. This means we spend a lot of time preprocessing the collected data before conducting data analysis.
Q. How do you expect this research to inform transportation agencies in New Jersey and elsewhere?
A. This type of research captures such rich data on travel behavior itself. Most of the literature using biometrics has been focused on driving, so this research expands the perspective. Here we’re focusing on slow mobility, like active travel and micromobility. Individuals who participate in slow mobility are more vulnerable road users, and we want to see how they behave in different travel environments. This can help agencies gain more insights into how to design safety infrastructure. Beyond that I can also envision the technology being used to evaluate whether certain improvements or infrastructure designs help to improve travel satisfaction or improve people’s experience at the same location by doing “before and after” studies. This type of study also allows you to measure and quantify the effect of the improvement.
The use of biometric sensors in the field can also be used to foster meaningful public engagement processes to show the lived experience of different people in a neighborhood or traveling through a different corridor, which can be very powerful.
Q. Do you feel the research methods are at a stage where they are “ripe” for use on other demonstration projects, planning or project development studies?
A. After one year of experimentation, our project team can readily work with biometrics. We have a good understanding of sensor limitations and how to set up the sensors to correctly reduce noise as much as possible. Our experience has also helped determine what kind of metrics can be extracted successfully and reliably through the sensors.
The most useful case for those sensors is to evaluate before and after, so that we can quantify how much people appreciate those implementations in a more accurate way. Beyond that, the sensors can also be effective infrastructure assessment tools. For example, imagine that you ask people to wear biometric sensors and do a bicycle infrastructure evaluation; the agencies can get more realistic and rich data compared with a more traditional survey approach. This rich data can help determine the most effective improvement. It ends up being more inclusive that way.
The tools can be very useful for fostering community engagement with vulnerable populations. For example, if agencies want to improve the accessibility for wheelchair users, they can ask individuals in wheelchairs to wear the sensors and move about an area. Recording and reviewing how they experience a journey is more powerful compared with just asking individuals with needs about their travel patterns. It’s going to be a more straightforward way to show the world how we can make the streets more inclusive for those vulnerable populations.
Q. Do you think local governments and non-governmental organizations could make use of biometrics sensors as a strategy to promote community engagement and outreach to local communities, or to address specific community safety or livability issues? Would it be cost-prohibitive to employ such tools for such community-based planning issues at this time?
A. From my point of view, the most effective way would be for the agencies to identify where there are needs and promising projects and then work with skilled researchers or practitioners who have these sensors already and have begun to climb the learning curve in the use of sensors and interpretation — for example, they could work with us. They would need to pay for the researchers’ time and participation incentives, or if they were to collaborate with a UTC (University Transportation Center) to conduct such research collaboratively.
The sensors are not the most expensive part of the study. The most expensive item is the researcher’s time to collect and analyze the data. The data are very complicated to analyze in the first place because it’s a large amount of data with noises. The researchers need to put in a lot of time to get it to the state where you can extract the relevant variables out and start to interpret them.
Q. How would you characterize the “state-of-training” in using biometrics for students or early career or mid-career professionals in transportation?
A. The biometric sensor itself is not very new, but new to the transportation field, especially for slow modes. It has been widely used in cognitive psychology, where there are classes to interpret those as well. Generally, I don’t think the current transportation and urban planning curriculum for students includes enough classes to cover those sensors. We probably need to teach not only biometric sensors, but urban sensing in general.
In an ideal course, students could get their hands dirty by putting those sensors in the field and then once the data are collected, they can learn how to preprocess and analyze the data. It would have to be a one-year kind of curriculum design to get people involved and ready for it. Of course, instruction on the use of sensors will differ by topic. For example, if you are working in the air quality field, then there are many different air quality sensors and each of them come with different data formats and require different experiment design and analytic skills.
Regarding the mid-career transportation professional, at this moment I believe the research is more in the academic field and focusing on testing and evaluation. I wouldn’t suggest that the research is so ripe that a mid-career transportation or urban planner professional should need to invest their time in learning how to use biosensors unless they have a research project that may benefit substantially from using the sensors.
Resources
To learn more about the use of biometrics in the field of active transportation, see:
Ryerson, M., Long, C., Fichman, M., Davidson, J.H., Scudder, K.N., Kim, M., Katti, R., Poon, G. & Harris, M., (2021). Evaluating Cyclist Biometrics to Develop Urban Transportation Safety Metrics. Accident Analysis & Prevention, Volume 159, 2021. Retrieved from https://www.sciencedirect.com/science/article/pii/S0001457521003183?via%3Dihub
Fitch, D.T., Sharpnack, J. & Handy, S. (2020). Psychological Stress of Bicycling with Traffic: Examining Heart Rate Variability of Bicyclists in Natural Urban Environments. Transportation Research Part F: Traffic Psychology and Behavior, Volume 70, 2020, Pages 81-97. Retrieved from https://www.sciencedirect.com/science/article/pii/S1369847819304073?via%3Dihub.
Zhang. W. 25th Annual NJDOT Research Showcase. Recording starts at: 59:00. Retrieved from https://youtu.be/D_rQP-Dv8gU
Zhang, W., Buehler, R., Broaddus, A. & Sweeney, T. (2021). What Type of Infrastructures do E-scooter Riders Prefer? A Route Choice Model. Transportation Research Part D: Transport and Environment, Volume 94, 2021. Retrieved from https://www.sciencedirect.com/science/article/pii/S1361920921000651.
For more information about the use of biometrics in the broader transportation field, see NYU’s C2SMART’s research project on Work Zone Safety:
Under the FHWA’s Climate Challenge, state DOTs and local agencies receive training and work with various stakeholders including those from industry and academia to implement projects that quantify the environmental impacts of pavements using Life Cycle Assessment (LCA) and Environmental Product Declarations (EPDs). EPDs provide an in-depth look at the use effects and environmental impacts of materials, processes, and mixtures. With a general goal to reduce carbon emissions, DOTs are moving towards the use of EPDs for selecting pavement uses and processes.
We spoke with Nusrat Morshed, Project Engineer in the Pavement Design & Technology Unit at NJDOT, about two FHWA project grants funded under the Climate Challenge initiative that she supervises. Both projects focus on the potential use of EPDs and LCA in New Jersey and will allow for NJDOT to develop a strong baseline understanding of EPD use.
FHWA – Funded Climate Challenge Projects
Q. Can you tell us about two FHWA-funded Climate Challenge projects listed for New Jersey. How is NJDOT currently involved in these FHWA funded projects? What are tasks for these projects?
A. NJDOT applied for this research project funding in early 2023 after the advertisement was released. I had spoken with representatives from Rowan University and Rutgers University to gauge their interest in this research, and both were on board. EPDs is a very new concept and term within the transportation field. This made it challenging to determine what the project scope should be for our grant applications. We received funding from FHWA immediately, but there were some technical issues in the allocation of state and federal funding shares that we needed to sort out before we could proceed. Both research teams officially began work in September and October of 2023 and they will have until the end of 2024 to carry out the work.
The research team for Project 1, Utilization of EPDs and LCAs to Promote Sustainability in NJ’s Pavements, is led by Dr. Yusuf Mehta from Rowan University and they are teamed with the research sub-consultant, Advanced Infrastructure Design (AID). The objective of this project is to utilize EPDs and LCAs to promote consideration of sustainability in maintaining NJDOT’s pavement infrastructure. The tasks within this project scope include: conducting a literature review, defining the goals and scope of the comparative LCA analysis, data collection, and analysis of results and interpretation.
The research team for Project 2, Improve Sustainability of Asphalt Pavement Overlay in NJ, is led by Dr. Hao Wang from Rutgers University. The research project objective is to improve the sustainability of asphalt pavement overlay in New Jersey. The project’s basic tasks include: documenting experiences and lessons of using FHWA’s LCA PAVE tool based on analysis of pavement overlay project in New Jersey DOT, evaluating quantification methods for calculating carbon emissions at the use phase of pavement, providing recommendations for use of LCA in decision making of pavement overlays, and preparing a final report and presentation.
Example EPD summary, retrieved from USDOT FHWA Tech Brief: Building Blocks of Life-Cycle Thinking
I am the key point person for both projects.
Q. What is the status of these FHWA funded projects? What resources have been helpful so far?
A. Both projects are underway now but still in the early stages. I received a status report from Project 1 about a month ago and expect a status report from Project 2 before March. For both projects, the focus has been to complete a literature review. One resource that was particularly helpful was the National Asphalt Pavement Associations (NAPA) website, as they have a lot of information on EPDs — 15 EPDs thus far have been identified — which are NJDOT specifications. We have also reached and had a meeting with the Port Authority of New York and New Jersey (PANYNJ) to get information on their own EPD process.
Q. The FHWA Climate Challenge program seems like it has established an approach to promote knowledge sharing and fostering a community of practice. Can you tell us about it? A. Every quarter, FHWA conducts a climate challenge webinar, and on this webinar there is usually a featured presentation from an expert and then brief update presentations from climate challenge project teams. These project teams extend beyond New Jersey, so other states can hear how NJDOT is doing with these projects and we can learn from our peers in other states.
Previously our updates have been limited to 2 or 3 slides, however, later this spring I will have two reports to base our presentation upon, which will be more comprehensive and reflective of NJDOT’s progress.
Attendees at a Climate Challenge Training session. source: FHWA
The quarterly webinars have been helpful and instructive. EPDs and sustainable resiliency are also very hot topics and several other resources are emerging that we can reference. For example, there was an entire session on EPDs at the Transportation Research Board’s Annual Meeting. Published literature has also been very helpful.
As a part of the project grants, FHWA is providing EPD-specific trainings. Both research teams and I have brainstormed about trainings our teams require. I have coordinated with FHWA as a Climate Challenge member and explained our training needs for accomplishing these two projects. FHWA and I drafted an agenda based on these research needs and we have scheduled a day and a half in-person training for March 2024. I requested that both of my teams submit their findings, as a status report before that training. So it also will be our official first status meeting for both project teams.
As a Project Engineer overseeing these projects, I am not able to work directly with the research, but I provide guidance to the universities and have been the communication bridge between them and FHWA. The training is hosted by FHWA and conducted by FHWA and a third-party organization that specializes in EPDs. These trainings are hosted throughout the U.S. To make this happen, FHWA provided us with their schedule, and we negotiated a time for them to do the training in March 2024.
Q. Who was in attendance for this training?
The training was done on March 12-13, 2024 at NJDOT. This training was focused on team members from both projects. There were representatives from the NJDOT Bureau of Materials, NJDOT Bureau of Statewide Strategies and NJDOT Division of Environmental Resources who participated.
Q. How has this funding assisted with NJDOT’s Every Day Counts (EDC) EPDs related goal?
Unless a NJ STIC Incentive Grant is awarded, FHWA does not provide any funding directly for advancing the EDC-7 innovation, but instead supports the deployment goals through the mobilization of FHWA resource specialists or subject matter experts who are farther along with innovation’s deployment. Luckily, the research of EPDs is a goal within EDC-7, so both of the funded Climate Challenge projects are indirectly supporting that EDC-7 goal.
Q. Have any pilot programs begun?
As we are still in the research stage for EPD use, we have not created any pilot programs yet.
Environmental Product Declarations in the Future
Q. Can you describe the status and implementation goal for NJDOT’s EDC-7 goal for advancing EPDs in New Jersey?
NJDOT’s EDC-7 goal for advancing EPDs in New Jersey is still in the preliminary stages of information gathering. Both of these climate challenge projects will assist with building up a robust set of literature that is necessary for next steps. Our goal is to get ideas for future recommendations. As of now, I would say we need to identify a few plants or suppliers and get some real-time data for different types of considerations based on research needs. Then we need to identify which way we can achieve EPD targets like lowering carbon emissions.
The stages of Pavement’s life cycle. Retrieved from USDOT FHWA Sustainable Pavements Program.
Q. What challenges, if any, has NJDOT faced while working to incorporate EPDs into pavement considerations?
EPD is based on many stages, which require their own literature review. For example, a product category rule, or a set of rules for measuring life-cycle analysis must be developed first. EPDs have different stages that all must be measured — specifically, the production stage, transportation stage and construction stage, or as they are called the A1, A2, A3. Achieving the goal of reduction in carbon emissions through EPDs requires a lot of research and literature review, and it will not be easy to get all the needed information, even when speaking with experts. Starting from scratch, the ability to quantify an EPD could take at least two years. So, it’s not that you will be getting something very quickly. We are just exploring now what is out there and how we can think about something in terms of New Jersey’s pavement mixes.
Q. How does NJDOT use or reference the published EPDs in New Jersey as reported by the National Asphalt Pavement Association’s Emerald Eco-Label tool?
We have looked at the National Asphalt Pavement Association (NAPA) website and reviewed their own PAVERS tool. It has been helpful to see how they do life-cycle analysis. They have their own LCA tool and we use the FHWA LCA tool — so there will most likely be differences. The FHWA LCA tool is expected to be updated soon.
Q. Do you foresee NJDOT having an embodied carbon clause added to NJDOT contract specifications? Will contractors be expected to submit an asphalt mix that provides EPDs to be considered for future contracts?
LCA PAVE Tool assists with analysis and quantification of the environmental impacts of existing products or processes. Retrieved from USDOT FHWA
Yes, definitely, we can dream, but it will take time. We need to identify and set the product category rule. More research is needed, maybe there will be future training opportunities on this topic from FHWA.
Q. Where is the biggest research gap when it comes to the incorporation and use of EPDs? Is it research on the pavement itself, or life cycle analysis, or something else?
EPD is not a single term, but a combination of a lot of things. In the process of determining an EPD for one pavement treatment, you must consider the process of installation, the type of pavement or asphalt mix, the binder and aggregate within the mix, etc. Because each of these processes require their own considerations, we must make the decision on what process and pavement, or asphalt mix should be evaluated first. We can then use our results to determine where the use of EPDs would be most helpful, or which process should be studied next. In other words, we cannot do everything at once, but rather start very specifically and focused, and then move out.
The five steps of developing Environmental Product Declarations (EPD). Retrieved from Tech Brief: Building Blocks of Life Cycle Thinking
Q. Has NJDOT had an opportunity to use or test the FHWA LCA Pave Tool? If so, how does it use the tool?
I have used that tool before, but I just use it as a general gauge as I don’t have any real-time data currently. I will need training in the future on how to efficiently use the tool based on actual data. I also think this tool will be helpful in the future for determining if our results are realistic. Our research team members are using this tool.
Q. How are you feeling about this initiative?
As a state government employee, I see this initiative as an effort that will help NJDOT be aligned with NJ’s clean energy policies. EPDs are a new topic for us, and everyone is very interested in learning more about it, including me. The funding opportunity that FHWA provided allows DOTs throughout the U.S. to explore this new topic and determine its applicability in the future of pavement and asphalt design.
Meijer, J., Harvey, J., Butt, A., Kim, C., Ram, P., Smith, K., & Saboori, A. (2021). LCA Pave: A Tool to Assess Environmental Impacts of Pavement Material and Design Decisions-Underlying Methodology and Assumptions (No. FHWA-HIF-22-033). United States. Federal Highway Administration. Retrieved at: https://www.fhwa.dot.gov/pavement/lcatool/LCA_Pave_Tool_Methodology.pdf
UHPC for Bridge Preservation and Repair is a model innovation that was featured in FHWA’s Every Day Counts Program (EDC-6). UHPC is recognized as an innovative new material that can be used to extend the life of bridges.Its enhanced strength reduces the need for repairs, adding to the service life of a facility.
This Q&A article has been prepared following an interview with Jess Mendenhall and Samer Rabie of NJDOT, who provided an update on the pilot projects of UHPC around the state. The interview has been edited for clarity.
Q. While EDC-6 was underway, we spoke with your unit about the pilot projects being undertaken with UHPC. Some initial lessons were shared subsequently in a featured presentation given to the NJ STIC. Can you update us on results of those projects, and did they yield any benefits in the fields of safety or environmental considerations?
For the NJDOT Pilot Project, the thickness of the overlay was limited by the required depth for effectiveness, as well as the cost of the UHPC material and environmental permitting. To mitigate environmental permitting, we avoided any modifications to the existing elevations and geometry of the structure. Essentially, any removal of asphalt and concrete needed to be replaced to its original elevations.
UHPC overlays can significantly extend the service of bridge decks and even increase a structure’s capacity. Although safety improvements were not the primary objective of this application, there were rideability and surface drainage considerations in the design to enhance the conditions for the road users.
The environmental impacts of structural designs must be compared on the cradle-to-grave use cycle of the design at a project scale. Having a focus on sustainability is imperative; however, it is more meaningful when resiliency is also considered. While the greenhouse gas emissions of a volume of UHPC are higher than those of the same volume of concrete, UHPC enables the reduction in the amount of material required in structural designs and improves the durability of structures. Its exceptional compressive strength and toughness allow for the reduction of material usage. By minimizing maintenance requirements and extending the lifespan of infrastructure, UHPC reduces the consumption of materials, energy, and resources over time.
For example, we installed this overlay on 4 bridges as a preservation technique. Had we done nothing, they would have lasted approximately 10 more years. During that time they would have needed routine deck patching resulting in further contamination of the decks and in a condition that is no longer preservable and requires total deck replacement, with large volumes of concrete and much more environmental impact.
UHPC allowed us to take these decks that are still in decent shape and preserve them now with a relatively thin layer to make them exceed the service life of the superstructure and substructure.
Q. Has UHPC been incorporated into the design manual?
Figure 1. UHPC being placed by workers
It is not in our current design manual, but we are working on the revised design manual. UHPC is presently being used for all closure pores between prefabricated components, overlays, and link-slabs. I don’t think we are ready to standardize it quite yet. We used it on the 4 bridges and it will continue to be used, but we will not standardize it until the industry is more predictable and we get more experience to develop thorough guidelines and specifications. It is incorporated into projects as a special provision with non-standard items.
Q. Have you been receiving more requests to use this technology from around the state?
It is much more commonly specified by designers or requested for use on many of our projects. We have responded to nationwide inquiries from state transportation agencies and universities seeking our specifications or input on specific testing and procedures.
Q. What efforts do you think can be taken to encourage more adoption amongst local agencies, counties, etc.?
We are keen on inviting the counties to any training or workshop that we are hosting as well as sharing our lessons learned thus far. I think they are aware of it.
Q. What kind of hurdles do you think exist that may limit widespread adoption?
It is possible that initial cost and industry experience with the material are still major limiting factors in adoption. We have also learned from specialty UHPC contractors that the innovation and availability of construction equipment geared for UHPC implementation are also lacking. Bringing into focus the life cycle costs and with more implementations, we think many of these hurdles will be overcome. Additionally, once UHPC is used more in routine maintenance the implementation would be more frequent and widespread; we know there is interest specifically in UHPC shotcrete once it is available.
Q. Are you familiar with any training, workshops, or conferences that have been done for staff or their partners on this topic?
We participated in the Accelerated Bridge Construction (ABC) conference in Miami, Florida, the International Bridge Conference (IBC) in Pittsburgh, Pennsylvania and the New York State DOT Peer Exchange. In Delaware, we presented at the Third International Interactive Symposium on UHPC. We also participated in the development of a UHPC course for the AASHTO Technical Training Solutions (TTS formerly TC3) which is now published on the AASHTO TTS portal and available on our LMS internally.
Q. Do you think there is any special training needed for the construction workforce to start using this technology?
Absolutely, the AASHTO TTS course and the EDC-6 workshops are geared towards the design and construction, TTS is more focused in the Construction. It’s an introduction to what to expect and how to implement it. UHPC is often used for repair projects, and many contractors may not have the experience or comfort with using the material.
Figure 2. UHPC Testing at Rutgers’ CAIT
Q. What are the results of the pilot projects of UHPC?
This Pilot projects program demonstrated that UHPC overlays can be successfully placed on various structures, the work can be completed rapidly to minimize traffic impacts — we estimated roughly four weeks of traffic disruption per stage, and the benefits of UHPC can help preserve the existing infrastructure. Compared to deck replacement, UHPC overlays can rehabilitate a bridge deck at exceptional speeds with unique constructability and traffic patterns, as implemented in all four structures. However, limitations exist, and further research is necessary to investigate the issues identified in the pilot project, but the potential of this material outweighs the existing limitations.
Q. Has there been long-term testing data developed to gather performance data?
To assess the performance of the UHPC overlay, we put together a testing program to include NDT as well as physical sampling and lab testing. This objective will be accomplished by first establishing baseline conditions through an initial survey followed by periodic monitoring of the UHPC-overlaid bridges over succeeding years. This will help NJDOT assess the performance of UHPC as an overlay. Overall, the results show the overlay bond is performing well.
Q. Has the data from the pilot project been used to research further applications?
Further applications for UHPC overlay are on new bridge decks/superstructures, and the data from UHPC overlay research project are being used for these projects. There is an interest in header reconstruction with UHPC. If deck joints need to be replaced, they should be constructed with conventional HPC with UHPC at the surface to provide the same overlay protection over the entire structure. Also, self-consolidating and self-leveling UHPC was preferred for the full-depth UHPC header placement to ensure proper consolidation around tight corners and reinforcement. This will be further explored for maintenance operations as well.
For future projects, in lieu of full-depth header reconstruction in a single lift, a partial depth header removal and reconstruction or alternatively two lifts of header concrete should be evaluated to coincide with the deck overlay, in which case the benefits of the fast cure times from UHPC can still be realized. Two of the four bridges experienced air voids throughout the placement. A UHPC slurry with no
fibers was placed in the identified air voids; since the voids contained exposed fibers, they were considered to create adequate bonding with the UHPC slurry.
The State of New Jersey has advanced policies, programs, and projects such as complete streets that encourage greater transportation modal choice and less dependency on the single-occupancy vehicle to address climate change and promote mobility and access for all users. The NJ Statewide Bicycle and Pedestrian Master Plan and Complete Streets policy seek to increase connectivity and micromobility safety through road diets and other infrastructure changes. New Jersey Department of Transportation (NJDOT) is also sponsoring safety programs that aim to reduce traffic related fatalities. In-depth research that looks at differences across gender, race, socioeconomic status and ability may assist in expanding policies and statewide initiatives that prioritize safety and accessibility for all road users.
This Q&A article has been prepared following an interview with Dr. Hannah Younes, a post-doctoral researcher at the Alan M. Voorhees Transportation Center at Rutgers University, who focuses on cyclists and e-scooter behavioral patterns. Her most recent study conducted in Asbury Park, NJ observed gender differences of chosen micromobility mode, helmet usage, and location. We interviewed her to better understand the data sources and methods used in the research, its limitations and explore the applicability and implications of her research findings to the field of transportation and future research. The Q&A interview has been edited for clarity.
Q. How was your research funded?
This work was supported by the National Science Foundation under a grant called “Making Micromobility Smarter and Safer”. The lead on this is Dr. Clint Andrews at Rutgers University and there are several other principal investigators. My study acts as a part of this multi-year research.
Q. Can you share a brief overview of your findings? Are the results surprising or unique compared to past research?
We are one of the only studies comparing the safety behavior of cyclists and e-scooter users across genders. Without considering gender, we found that one-third of cyclists wore a helmet. We also found in our observations that e-scooter users did not wear a helmet. It speaks to how important it is to have safe micromobility infrastructure, especially knowing that people are unlikely to wear a helmet. In the U.S., even if you give everyone a helmet, they’re probably not going to wear it. That’s just how it is. Keeping people safe in other ways is paramount.
The temporary bike lane created as a part of Dr. Younes research. Asbury Park, NJ
We also found that a greater proportion of women were using e-scooters than bicycles. This is important because cycling has long been a male-dominated mode of transportation, for a variety of reasons. That is true across the world. There are studies that suggest women are less likely to cycle to work because of clothing like wearing a skirt or dress or heels, or fears of sweating. E-scooters remove that hurdle since they are not as prohibitive in terms of clothing and require less physical exertion. So, the vehicle type itself may make a difference. Moreover, women place more importance on bike lane infrastructure than men. If we are seeing that e-scooters are the preferred mode for females, perhaps e-scooters can help narrow the gender gap in micromobility.
Q. Can you talk a little bit about the methods used for this study? How are these methods different from past research? Why did you choose to use traffic cameras for your observations?
This work was done using manual observations, a common method in micromobility studies. Previous research had used observations collected in the field. Instead of having observers in the field, we observed traffic camera footage at one intersection. Because we were observing gender and race as well as group behavior, the footage was useful as it allowed us to pause when needed. It was also less resource intensive than having a person stand in the field since no travel expenses were associated with the analysis.
Q. What challenges have you found in working with and interpreting traffic camera footage? With the improvement of AI technologies, do you think there will be an opportunity to automate this process in the future? Are there any limitations you expect from this type of innovation?
It is very time consuming and tedious to analyze this much camera footage. We analyzed 35 hours of footage. I would love to have analyzed more, but you have to draw the line somewhere depending on the resources available for the research or project study. Most of the time, we fast forwarded until a micromobility user was detected, but it still requires undivided attention. There is a possibility with current technology to incorporate AI technologies: to use computer vision to detect humans, which then can be manually viewed by a human to assess micromobility mode, gender, and helmet use. This would likely reduce the manual labor… It would be interesting to compare the computer vision model to the work I have done… Nonetheless, computer vision does not differentiate properly between pedestrians and e-scooter users, so it is prone to misidentification, which would lengthen the time taken to observe manually.
The view from the intersection traffic camera. Asbury Park, NJ
At this point, computer vision cannot detect gender, helmet use, and group riding properly from traffic camera footage. More high-resolution images would be needed to differentiate gender and helmet use (like unobstructed face images) and group riding requires context clues like making eye contact, waiting for one another, etc. AI has the potential, but it is not there yet. As time consuming as it is, I am confident that we detected every person, which is why we chose to observe the footage ourselves.
Q. What are the limitations of this study? Do you have plans for future research to address these? How would you like to expand your research on this topic?
The main limitation is the geographical scope of this research; it’s a lot of work for one city. We only analyzed the behavior of micromobility in one location, Asbury Park. It isn’t clear how much the results will translate from one location to another. Mode of transportation and behavioral use depends on many different factors that vary from location to location. There is evidence that the gender gap is smaller for e-scooter users in Brisbane, Australia, but not to the extent observed in Asbury Park. Same goes with helmet use. A larger scale study would be useful. Other limitations include the types of micromobility modes: we only observed shared e-scooters and privately owned bicycles in Asbury Park. So, we’re comparing two different vehicles and two different share types to one another. When analyzing the data, we must consider both of these factors. For example, are behaviors attributed solely to the vehicle or to the share type? Probably both. When you’re looking at the gender gap, is it because it’s an e-scooter or is it because it’s shared that there is a narrower gender gap?
An analysis comparing shared and privately owned e-scooters with shared and privately owned bicycles would be great. Differentiating between e-bikes and bicycles would be great too, although the resolution of traffic camera footage makes it very hard to differentiate between the two. Even with an observer onsite, it would be hard to detect, so you would need a survey, but this could alter behavior. In Asbury Park, a lot of people have privately owned e-scooters now, so we could do another study in 1.5-2 years and get additional insights in the same location.
E-bikes are a growing mode of transportation, but even with traffic camera footage, it is very hard to tell an e-bike apart from a bicycle, so maybe in that case you would need somebody on site actually observing. You’re losing the ability to pause footage, but it might be more useful if you’re looking at e-bikes. Race and age were also very difficult to observe from the footage. It could be easier if someone was in person to observe in addition to the traffic camera footage. Even then, without asking directly the age and race/ethnicity of the user, there will be bias. There are a lot of different things to consider; it really depends on what the question is.
Q. How would you like this research to inform transportation agencies and practitioners in New Jersey and elsewhere?
There are several key points. Users of shared e-scooters and privately owned bicycles are different and behave differently. E-scooter users are more likely to take risks like not wearing a helmet or riding on the road. Planners must ensure that the infrastructure keeps them safe. That is, implementing dedicated protected bike lanes that are connected to a greater network and adding traffic calming measures to slow the speeds of motor-vehicles like raised crosswalks or narrower traffic lanes.
Understanding the reasons behind lane use is important as well, as there are concerns for pedestrian safety. Our research observed that lane use was different; for example, 7 percent of male cyclists rode on the sidewalk, compared to 28 percent of female e-scooter users.
Additionally, having a shared e-scooter system in a city can increase female participation in micromobility use. It is a more gender equitable mode than bicycles. Other agencies might want to implement an e-scooter share program in their town.
Q. Your research shows that women were more likely than men to ride on the sidewalk while using an e-scooter or bike. Given that this strategy is illegal in most parts of the country, how can planners, engineers and policymakers use this information to increase feelings of safety for female micromobility users?
This is really interesting. From my research, there is not a lot that I could say. Implicitly, one of the reasons for someone to ride on the sidewalk instead of the road is that they feel safer on the sidewalk. There is a need to ensure that micromobility users feel just as safe on the road–that is, implement a dedicated and protected bike lane, and provide a clear separation from motor-vehicles.
From our work, we know that there are other more complex factors at play: our research had clear results for road lane use with the implementation of the bike lane, but less clear ones for sidewalk use: sidewalk use was not significantly reduced by the presence of a pop-up bike lane. To encourage safe road use, ensuring a complete network would be a start. The pop-up bike lane was not connected to another bike lane going downtown, for instance. If you’re already coming downtown on the sidewalk, you might be more likely to stay there given the existing curb that would need to be crossed to go from the sidewalk to the pop-up bike lane.
Representation of bidirectional bicycle lanes Image via Streetmix. Ensuring cyclists and e-scooter users have safe infrastructure as shown above is important for all road users’ safety.
Q. NJDOT is sponsoring a program to ensure the implementation of the Statewide Bicycle and Pedestrian Master Plan. In what ways could this master plan or a future one align with the findings in your study?
The results of this study reinforce that implementing a bike lane provides a layer of safety for micromobility users. Nearly all the increase in bike lane usage came from a reduction in traffic lane usage, not in sidewalk usage. There is so much research out there that shows that bike lanes save lives; in the case of a crash, someone in a bike lane is less likely to be injured. Ensuring that plans accommodate both bicycles and e-vehicles–like e-bikes and e-scooters–is also paramount.
Q. The Biden Administration has set a goal to achieve a net zero emissions economy by 2050. How might a shift toward micromobility help the nation reach its climate and carbon emission goals?
Bicycles are zero emission vehicles. E-bikes and e-scooters produce few emissions, especially privately owned ones since they don’t require rebalancing. Rebalancing shared vehicles requires a car or van and those gasoline emissions are absorbed by those shared e-scooters. Having an e-vehicle do that for rebalancing helps to reduce those emissions. Bicycle-friendly infrastructure, which reduces motor-vehicle infrastructure such as the number of traffic lanes, or parking, can also reduce motor-vehicle use and induce more environmentally friendly travel.
Q. How could a focus on reaching these climate goals impact the way that planners and engineers design streets?
Motor-vehicle travel is the most polluting transportation mode. A shift towards micromobility Infrastructure, particularly in cities, can help induce travel from eco-friendly modes and reduce motor-vehicle use. This should be in conjunction with other measures, such as increasing gasoline prices, increasing parking costs, and providing subsidies for eco-friendly modes.
Marshall, H. (2023). “How do Female Cyclists Perceive Different Cycling Environments? – A Photo-elicitation study in Stockholm, Sweden.” Retrieved from https://gupea.ub.gu.se/handle/2077/78209
The Complete Streets planning approach pushes for a future in which people of all ages and abilities can safely travel. Recently signed NJ legislation takes an important step toward this vision by ensuring that the travel needs of cognitively divergent individuals are addressed in Complete Streets Plans.
In January 2023, Governor Phil Murphy signed S-147 into law, directing the New Jersey Department of Transportation (NJDOT) to update its Complete Streets policy to consider and implement design elements and infrastructure projects that promote the ability of persons diagnosed with autism spectrum disorder (ASD) and persons with intellectual and developmental disabilities (IDDs) to travel independently.
This requirement follows important research conducted by Rutgers CAIT and VTC and funded by NJDOT, in which the travel behavior of over 700 adults with autism spectrum disorder (ASD) was studied. The research concluded that individuals with ASD, seeking to travel independently, experience extraordinary transportation barriers that are complicated by the state’s auto-oriented street design and land uses. With fewer such persons driving cars, an improved network of walking and biking infrastructure opens a world of opportunities for engagement in civic life and to reaching essential destinations via public transportation.
The Complete Streets Summit event will include a session on efforts underway to revise policies to promote travel independence for ASD with IDD persons.
NJDOT has undertaken a project that seeks to address how to accommodate the travel needs of people with ASD and/or IDDs through policy and design. The Department’s Bureau of Safety, Bicycle and Pedestrian Programs has engaged the Rutgers-Voorhees Transportation Center, NV5, Toole Design Group and a working group of NJDOT planners and engineers to assist with addressing the travel needs of cognitively divergent persons – and with meeting the requirements of the legislation.
The research team is developing a primer on Complete Streets and neurodivergence and will use the information gathered to help NJDOT develop universal design guidelines that will ensure the Department’s Complete Streets policy considers the needs of those with ASD and IDDs. The team will be sharing more information at the upcoming 2023 New Jersey Complete Streets Summit on November 1st. Not yet registered? Register Here.
A recently completed research study on NJ TRANSIT grade crossing safety focuses on identifying locations for rail grade crossing elimination. Researchers from Rutgers’ Center for Advanced Infrastructure and Transportation (CAIT), Asim Zaman, P.E., Xiang Liu, Ph.D., and Mohamed Jalayer, Ph.D., from Rowan University, developed a methodology using 20 criteria to narrow a list of 100 grade crossings to ensure appropriate identification for closure. The process helps NJ TRANSIT and New Jersey Department of Transportation (NJDOT) to direct limited funds to areas of greatest need to benefit the public.
Across the country, 34 percent of railroad incidents over the past ten years have occurred at grade crossings. The elimination of grade crossings can improve public safety, decrease financial burdens, and improve rail service to the public.
According to the proposed methodology, the 20 crossings recommended for closure located in Monmouth County (60%), Bergen County (25%), and Essex County (25%).
The researchers ranked grade crossings in New Jersey using the following data fields: crash history, average annual daily traffic, roadway speed, roadway lanes, length of the crossing’s street, weekday train traffic, train speed category, number of tracks, access to train platforms, intersection angle, distance to alternate crossings, distance to emergency and municipal buildings, whether emergency and municipal buildings are on the same street, and date of last or future planned signal and surface upgrades. This process resulted in a final list of 20 grade crossings eligible for elimination.
To understand how this study will be used, we conducted an interview with NJTRANSIT personnel Susan O’Donnell, Director, Business Analysis & Research, Ed Joscelyn, Chief Engineer – Signals, and Joseph Haddad, Chief Engineer, Right of Way & Support.
Q. How will the report inform decision-making?
It is important to have solid research and strong evaluation criteria, such as developed by this study, on which to base decisions for grade crossing elimination. In addition to the study, we looked at what other state agencies and transit agencies have done with grade crossing elimination, as well as criteria recommendations from Federal Highway Administration (FHWA) and Federal Railroad Administration (FRA). Following up on this study, NJ TRANSIT and NJDOT are considering next steps that would be needed to close the 20 identified grade crossings. In New Jersey, the Commissioner of Transportation has plenary power over the closing of grade crossings.
Q. What other information will be needed to assess these locations?
Local concerns about grade crossing elimination tend to focus on traffic re-routing, including the possible impacts on neighborhoods, time needed to reach destinations, and emergency vehicle access to all parts of a community. The criteria established by the study addressed these areas of concern. Prior studies have determined that the road networks around the identified locations are adequate to accommodate re-routed traffic. The current research study took into account the findings from those prior studies. As each project moves forward, NJDOT will determine if additional information will be needed.
Q. Is elimination of any of these grade crossings part of NJ TRANSIT’s capital program?
All of the closings are part of the capital program. Funding for the grade crossing elimination comes from the federal government and NJ TRANSIT. NJ TRANSIT funding is in place to close the crossings.
Q. Are there benefits of the research study beyond identification of the 20 grade crossings?
The research study developed the criteria and process for identifying grade crossings for elimination. This framework can be used in the future to assess other grade crossings for possible elimination. NJ TRANSIT is grateful to NJDOT for funding this important research project to improve safety.
For more information on this research study, please see the resources section below.
In 2019, a team of researchers from New York University and Rutgers University examined ways to calibrate and develop Safety Performance Functions (SPFs) to be utilized specifically to address conditions on New Jersey roadways. SPFs are crash prediction models or mathematical functions informed by data on road design. These data include, but are not limited to, lane and shoulder widths, the radius of the curves, and the presence of traffic control devices and turn lanes. With these data, SPFs help those tasked with road design and improvement to build roads and implement upgrades that maximize safety.
The Highway Safety Manual (HSM) presents SPFs developed using historic crash data collected from several states over several years at sites of the same facility type. These SPFs data cannot be transferred to other locations because of expected differences in environment and geographic characteristics, crash reporting policies and even local road regulations. To help SPFs better reflect local conditions and observed data, one of two strategies is usually undertaken to fine-tune SPFs: calibrating the SPFs provided in the HSM so as to fully leverage these data or developing location-specific SPFs regardless of the predictive modeling framework included in the HSM.
The research team, led by Dr. Kaan Ozbay (of NYU’s Tandon School of Engineering), chose to pursue both of these strategies. The research report, Calibration/Development of Safety Performance Functions for New Jersey, can be found here. A webinar highlighting the research and findings can be found here. A monograph, supported by the NJDOT funded study and partially by C2SMART, a Tier 1 UTC led by NYU and funded by the USDOT, was also recently published and can be found here.
C2SMART Webinar highlighted the research methods, findings, challenges and technology transfer efforts of the NYU-Rutgers team for this NJDOT funded research project.
SPFs can be utilized at several levels. At the network level, researchers and engineers use SPFs to identify locations with promise for improvement. SPFs can be used to predict how safety treatments will affect the likelihood of crashes based on traffic volume and facility type. SPFs can be used to influence project level design by showing the average predicted crash frequency for an existing road design, for alternate designs, and for brand-new roads.
SPFs also can be used to evaluate different engineering treatments. In this case, engineers and researchers return to a site where a safety countermeasure has been installed to collect and analyze data to see how the change has affected crash frequency. They examine before and after conditions and measure if the prediction made using the SPF was accurate or needs improvement (Srinivasan & Bauer, 2013). In the end, SPFs are only as good as the data used in their development.
NJDOT and the NYU-Rutgers team set out to calibrate SPFs using New Jersey’s roadway features, traffic volumes and crash data, and if necessary, to create new SPFs that reflect conditions in the state. The facility types considered for this research project included segments and intersections of rural two-lane two-way, rural multilane, and urban and suburban roads. In examining these datasets, the researchers identified areas where data processing improvements could be made to enhance the quality or efficiency in use of the data in addition to pursuing the stated goal of developing New Jersey-specific SPFs.
For example, utilizing the data provided by NJDOT, the research team developed methods for processing a Roadway Features Database of different kinds of road facilities. The researchers utilized the Straight Line Diagrams (SLD) database, which offers extensive information about the tens of thousands of miles of roadways in New Jersey, but observed issues and errors in the SLD database that required corrections. For example, the research team utilized Google Maps and Google Street View to conduct a manual data extraction process to verify information in the SLD database (e.g., confirm whether an intersection was an overpass, number of lanes, directionality) and extract missing variables, such as the number of left and right turn lanes at intersections, lighting conditions, and signalization needed for the analysis.
The research team using Google Street View to identify missing data points.
The research team also needed to develop programming code to correctly identify the type and location of intersections and effectively work with available data. The team developed a novel “clustering-based approach” to address the absence of horizontal curvature data using GIS centerline maps.
Utilizing Google Maps (Left) and the state’s Straight Line Database (Right), researchers were able to identify missing paths in the database that contributed to inconsistent data.
Police reports of crashes often have missing geographic identifiers which complicates analytical work such as whether crashes were intersection-related. In NJ, police are equipped with GPS devices to record crash coordinates but this crash information is somewhat low in the raw crash databases before post-processing by NJDOT. The researchers employed corrective methods and drew upon other NJ GIS maps to provide missing locations (e.g., Standard Route Identification or milepost).
The processing challenges for roadway features, traffic volumes and crashes encountered by the research team suggest the types of steps that can be taken to standardize and streamline data collection and processing to secure better inputs for future SPF updates. Novel data extraction methods will be needed to minimize labor time and improve accuracy of data; accurate crash data is integral to employing these methods.
The research team modified the spreadsheets developed by the HSM and used by the NJDOT staff. The calculated calibration factors and the developed SPFs are embedded in these spreadsheets. The users can now select whether to use the HSM SPFs with the calculated calibration factors or the New Jersey-specific SPF in their analyses
The researchers’ data processing and calibration efforts sought to ensure that the predictive models reflect New Jersey road conditions that are not directly reflected in the Highway Safety Manual. The adoption of this data-driven approach can make it possible to capture information about localized conditions but significant expertise is required to carry out calibration and development analyses. With more research—and improved data collection processes over time —the calibration and development of SPFs holds promise for helping New Jersey improve road safety.
C2SMART. (2020, September 23). Webinar: Bekir Bartin, Calibration and Development of Safety Performance Functions for New Jersey . Retrieved from YouTube: https://youtu.be/IRalyvjDaFM
Ozbay, K., Nassif, H., Bartin, B., Xu, C., & Bhattacharyya, A. (2019). Calibration/Development of Safety Performance Functions for New Jersey [Tech Brief]. Rutgers University. Department of Civil & Environmental Engineering; New York University. Tandon School of Engineering. Retrieved from https://www.njdottechtransfer.net/wp-content/uploads/2020/07/FHWA-NJ-2019-007-TB.pdf
Srinivasan, R., & Bauer, K. M. (2013). Safety Performance Function Development Guide: Developing Jurisdiction-Specific SPFs. The University of North Carolina, Highway Safety Research Center. Retrieved from https://rosap.ntl.bts.gov/view/dot/49505
Partnering with the Federal Railroad Administration, New Jersey Transit and New Jersey Department of Transportation (NJDOT), a research team at Rutgers University is using artificial intelligence (AI) techniques to analyze rail crossing safety issues. Utilizing closed-circuit television (CCTV) cameras installed at rail crossings, a team of Rutgers researchers, Asim Zaman, Xiang Liu, Zhipeng Zhang, and Jinxuan Xu, have developed and refined an AI-aided framework for detection of railroad trespassing events to identify the behavior of trespassers and capture video of infractions. The system uses an object detection algorithm to efficiently observe and process video data into a single dataset.
Rail trespassing is a significant safety concern resulting in injuries and deaths throughout the country, with the number of such incidents increasing over the past decade. Following passage of the 2015 Fixing America’s Surface Transportation (FAST) Act that mandated the installation of cameras along passenger rail lines, transportation agencies have installed CCTV cameras at rail crossings across the country. Historically, only through recorded injuries and fatalities were railroads and transportation agencies able to identify crossings with trespassing issues. This analysis did not integrate information on near misses or live conditions at the crossing. Cameras could record this data, but reviewing the video would be a laborious task that required a significant resource commitment and could lead to missed trespassing events due to observer fatigue.
Zaman, Liu, Zhang, and Xu saw this problem as an opportunity to put AI techniques to work and make effective use of the available video and automate the observational process in a more systematic way. After utilizing AI for basic video analysis in a prior study, the researchers theorized that they could train an AI and deep learning to analyze the videos from these crossings and identify all trespassing events.
Working with NJDOT and NJ TRANSIT, they gained access to video footage from a crossing in Ramsey, NJ. Using a deep learning-based detection method named You Only Look Once or YOLO, their AI-framework detected trespassings, differentiated the types of violators, and generated clips to review. The tool identified a trespass only when the signal lights and crossing gates were active and tracked objects that changed from image to image in the defined space of the right-of-way. Figure 1 depicts the key steps in the process for application of AI in the analysis of live video stream or archived surveillance video.
Figure 1. General YOLO-Based Framework for Railroad Trespass Detection illustrates a step-by-step process involving AI algorithm configurations, YOLO-aided detection, and how trespassing detection incidents are saved and recorded to a database for more intensive analysis and characterization (e.g., trespasser type, day, time, weather, etc.)
The researchers applied AI review to 1,632 hours of video and 68 days of monitoring. They discovered 3,004 instances of trespassing, an average of 44 per day and nearly twice an hour. The researchers were able to demonstrate how the captured incidents could be used to formulate a demographic profile of trespassers (Figure 2) and better examine the environmental context leading to trespassing events to inform the selection and design of safety countermeasures (Figure 3).
Figure 2: Similar to patterns found in studies of rail trespassing fatalities, trespassing pedestrians were more likely to be male than female. Source: Zhang et alFigure 3: Trespassing events were characterized by the gate angle and timing before/after a train pass to isolate context of risky behavior. Source: Zhang et. al
A significant innovation from this research has been the production of the video clip that shows when and how the trespass event occurred; the ability to visually review the precise moment reduces overall data storage and the time needed performing labor-intensive reviews. (Zhang, Zaman, Xu, & Liu, 2022)
With the efficient assembly and analysis of video big data through AI techniques, agencies have an opportunity, as never before, to observe the patterns of trespassing. Extending this AI research method to multiple locations holds promise for perfecting the efficiency and accuracy in application of AI techniques in various lighting, weather and other environmental conditions and, more generally, to building a deeper understanding of the environmental context contributing to trespassing behaviors.
In fact, the success of this AI-aided Railroad Trespassing Tool has led to new opportunities to demonstrate its use. The researchers have already expanded their research to more crossings in New Jersey and into North Carolina and Virginia. (Bruno, 2022) The Federal Railroad Administration has also awarded the research team a $582,859 Consolidated Rail Infrastructure and Safety Improvements Grant to support the technology’s deployment at five at-grade crossings in New Jersey, Connecticut, Massachusetts, and Louisiana. (U.S. DOT, Federal Railroad Administration, 2021) Rutgers University and Amtrak have provided a 42 percent match of the funding.
The program’s expansion in more places may lead to further improvements in the precision and quality of the AI detection data and methods. The researchers speculate that this technology could integrate with Positive Train Control (PTC) systems and highway Intelligent Transportation Systems (ITS). (Zhang, Zaman, Xu, & Liu, 2022) This merging of technologies could revolutionize railroad safety. To read more about this study and methodology, see this April 2022 Accident Analysis & Prevention article.
Tran, A. (n.d.). Artificial Intelligence-Aided Railroad Trespassing Data Analytics: Artificial Intelligence-Aided Railroad Trespassing Data Analytics:.
Zaman, A., Ren, B., & Liu, X. (2019). Artificial Intelligence-Aided Automated Detection of Railroad Trespassing. Journal of the Transportation Research Board, 25-37.
Zhang, Z., Zaman, A., Xu, J., & Liu, X. (2022). Artificial intelligence-aided railroad trespassing detection and data analytics: Methodology and a case study. Accident Analysis & Prevention.
