Reducing fatalities on rural roads is a key challenge for transportation agencies in the United States, where roadway departures on rural networks account for one-third of traffic fatalities. The Federal Highway Administration (FHWA) has identified safety countermeasures that are proven to improve rural roadway safety and reduce the number of traffic deaths. In the fifth round of the agency’s Every Day Counts (EDC) State-based model, FHWA identified “Reducing Rural Roadway Departures” as a proven, yet underutilized, innovation. The four pillars of the initiative are: all public roads, proven countermeasures, a systemic approach, and safety action plans. FHWA Proven Safety Countermeasures for rural roadway departures fall into three broad categories: helping drivers stay in their lane, reducing the risk of a crash with lane departures, and minimizing the severity in the case of a crash. Specifically, FHWA safety countermeasures related to rural roadway departures include rumble strips and stripes, SafetyEdgeSM, high friction surface treatment, and backplates with retroreflective borders. A recent FHWA video, Focusing on Reducing Rural Road Departures, provides information on how these low-cost measures help drivers stay in their travel lanes and reduce the potential, or minimize the severity, of rural roadway crashes.
Through EDC, FHWA seeks to support rapid deployment of identified initiatives at the State and local level, which results in cost, time, and resource savings. As of December 2019, New Jersey is in the “development” phase of the Reducing Rural Roadway Departures initiative; NJDOT is collecting guidance and best practices, while building support with partners and stakeholders to develop an implementation process. The goal is to reach the “demonstration” stage by the end of EDC-5 (December 2020), when they would begin testing and piloting the innovation.
In order to achieve this goal, NJDOT seeks to improve the knowledge of rural roadway facility owners and maintainers through training, with the assistance of the FHWA Resource Center. In 2018 and 2019, FHWA and NJDOT hosted a series of Local Safety Peer Exchanges at which engineering staff from Cumberland and Somerset counties shared their experience with implementation of countermeasures on high risk rural roads (HRRR).
FHWA’s Strategic Approach and Plan to reduce roadway departure crashes and fatalities. Photo Source: FHWA, 2019.
The Cumberland County Engineering Office manages infrastructure that includes 540 miles of county roads, 50 traffic signals and flashers, 54 bridges, and 169 minor bridges. One important source of funding for their work is the Highway Safety Improvement Federal-aid Program (HSIP). The purpose of HSIP is to achieve a significant reduction in highway fatalities and serious injuries on all public roads, using a data-driven, strategic approach focused on improving performance. The County focuses on two types of projects for HSIP: systemic projects and “hot-spot” projects. Systemic projects apply a given improvement method over a large number of applicable locations in order to deter “random” crash events and reduce risk across an entire roadway system.
Hot-spot projects need more in-depth data collection and analysis to determine appropriate site-specific improvements related to crash history. To collect data for hot-spot projects, South Jersey Transportation Planning Organization (SJTPO), the regional Metropolitan Planning Organization (MPO) for Cumberland County, worked with Rutgers University’s Center for Advanced Infrastructure and Transportation (CAIT) to use NJDOT’s Plan4Safety multi-layered decision support tool to create four network screening lists for the region. Each list provided weighted scores for a given timeframe based on a location’s number and severity of crashes. The four screening lists identify pedestrian intersection hot spots, pedestrian corridor hot spots, intersection hot spots, and HRRR hot spots.
Selecting the appropriate countermeasure is critical to project success. When using network screening lists, the countermeasure should address the particular type of crash occurring at the location, while countermeasures used with the systemic approach should address the specific geometric trait(s) that are related to the specific crash type.
Cumberland County highlighted two countermeasures at the Peer Exchange: centerline rumble strips and high friction surface treatment on horizontal curves. Centerline rumble strips reduce the risk of cross centerline crashes and are often part of a systemic approach. With the help of NJDOT’s Bureau of Transportation Data and Safety, SJTPO created a candidate list of potential centerline rumble strip locations. NJDOT’s criteria limit installation to two-lane urban or rural roadways with a 20-foot minimum pavement width, and a speed limit of 35 mph or greater. In addition, Cumberland County limited installation to asphalt roadways 10 years old or less in less dense residential neighborhoods due to the noise the rumble strips produce. Based on these criteria, the County selected approximately 150 roadway miles across 11 municipalities. Installation was performed at night to lessen the impact on traffic, improve safety conditions for construction workers and inspectors, and shorten installation time.
HFST installation at a horizontal curve. Photo Source: FHWA, 2018.
The second method, high friction surface treatment (HFST) on horizontal curves, addresses the challenges that horizontal curves pose due to the change in alignment that can cause issues for driver navigation, especially at night or in inclement weather. According to data analysis cited by SJTPO, 28 percent of fatal crashes nationwide occur on horizontal curves. HFST compensates for the high friction demand at the curves in areas where the current pavement condition does not adequately support operation speed, due to a number of factors such as sharp curves, wet conditions, polished roadway surfaces, inadequate cross-slope design, and driving speeds above the curve advisory speed. HFST are proven to reduce wet road crashes by 52 percent and curve crashes by 24 percent according to the FHWA. Additionally, these treatments are safe for all vehicle types and have high durability. However, the county engineer also noted the high unit cost and the lack of contractors within the region capable of HFST installation. When properly installed, the pavement life is equal to, our greater than, asphalt pavement but improper installation potentially limits the usefulness and life expectancy of the pavement treatment.
Locations were selected from the HRRR list, along with spots familiar to the Engineering Department based on geometry, crash history, residential input, and municipality information. Additionally, pavement condition was taken into consideration as a factor that could affect the treatment’s durability.
Cumberland County staff highlighted the importance of updating and upgrading existing safety features during the project such as size, location, spacing, and retroreflectivity of signage. They noted important considerations moving forward: data used in the network screening lists is aging; the rumble strip projects had a long delivery timeline of 22 months from application submission to construction notice to proceed; and the centralized project review process eliminated interactions with the local public agency which tends to have the most detailed knowledge of the project area.
Cumberland County High Risk Rural Roads Locations in Cumberland County. Photo Source: Whitaker, 2018.
A representative of the Somerset County Engineering Office shared their systemic safety approach to horizontal curves with high friction surface treatment. The Engineering Office manages infrastructure for 250 miles of county roads, 193 traffic signals, and 762 bridges, along with county sites, facilities, and parks. Annually, their work includes 15 miles of road resurfacing, 1.2 miles of road reconstruction, 7 bridge replacements, installation or upgrade of 10 traffic signals, and replacing more that 150 ADA curb ramps. The catalyst to pursue pavement friction treatments was the availability of crash data from the Plan4Safety crash database, which allowed Somerset County and their MPO, North Jersey Transportation Planning Authority (NJTPA), to analyze crash trends in the region in order to plan for infrastructure improvements based on need and types of issues.
Based on this analysis, the county identified and prioritized horizontal curves where they decided pavement friction treatments would be the best countermeasure. The next questions they had were: what is the correct treatment method; when is treatment appropriate; and how do they determine the length of need on the horizontal curve. Initially, the county used micro milling which provides a high friction surface to reduce “run-off’ road crashes for a low cost of installation. Downsides for the treatment include a short life expectancy, complaints from motorcyclists and bicyclists, and negative public perception associated with milling a newly paved surface.
Based on this experience, the county turned next to high friction surface treatment as an option that is safe for all vehicle types and has a longer life expectancy than micro milling. As did Cumberland County, Somerset County noted the treatment’s high cost at $35-65 per square yard and the specialized nature of the installation. Somerset County’s evaluation method for determining when HFST should be used requires the following data: centerline alignment geometry, roadway cross slope, road profile slope, posted speed limit, and posted curve advisory plate speed. The resulting evaluation produces friction ranges to guide the action taken.
Initial micro milling treatment in Somerset County. Photo Source: Bates Smith, 2017.
Somerset County found a comparison of crashes in the years prior to the treatment with crash data from the year after the treatment revealed a significant reduction in crashes, although they cautioned that there may be other factors at play. In the case of Chimney Rock Road, annual crashes dropped 84 percent from 73 to 12 for the year after HFST was applied to 5 curves on a 1-mile road segment. Looking to the future, the county plans to prioritize high crash locations for evaluation to either implement additional signage or HFST, based on data from GIS crash mapping, along with the NJ Regional Curve Inventory and Safety Assessment for the NJTPA region. They additionally highlighted important resources that have emerged, including the FHWA’s HFST Curve Selection and Installation Guide.
Cumberland and Somerset counties are just two examples of rural roadway departure safety improvements happening around the state. In the NJTPA region, Monmouth County received $2,967,000 from NJTPA’s FY 2017-18 High Risk Rural Roads (HRRR) Program for corridor improvements on Stage Coach Road in Upper Freehold Township, including the application of high friction surface treatment, safety edging, and centerline rumble strips. To help support and expand these efforts, NJDOT will be holding train-the-trainer events at DVRPC, SJTPO, and NJTPA later this year for county and municipal representatives, MPO staff, and NJDOT staff. This training will help New Jersey advance to the next stage of this EDC-5 initiative and improve safety on rural roads throughout the State.
Featured Image Source: FHWA, 2016.
Resources
Bates Smith, P. (2019). Pavement Friction Surface Treatments. Retrieved from https://www.njdottechtransfer.net/wp-content/uploads/2019/04/E_Somerset-PAVEMENT-FRICTION-surface-treatments-3-21-19.pdf
FHWA. (2019). Reducing Rural Roadway Departures. Retrieved from https://www.fhwa.dot.gov/innovation/everydaycounts/edc_5/roadway_departures.cfm
FHWA. (2020). Proven Safety Countermeasures. Retrieved from https://safety.fhwa.dot.gov/provencountermeasures/
FHWA. Focus on Reducing Rural Roadway Departures (FoRRRwD) Overview Video. (2019). Retrieved from https://www.youtube.com/watch?v=WfdBrrl0WwU&t=87s
NJTPA. (2020). Local Safety Program/High Risk Rural Roads. Retrieved from https://www.njtpa.org/localsafety.aspx
SJTPO. (2020). Highway Safety Improvement Program – Safety Infrastructure. Retrieved from https://www.sjtpo.org/hsip/
Whitaker, D. W. (2018). Systemic Safety Improvements. Retrieved from https://www.njdottechtransfer.net/wp-content/uploads/2018/06/Cumberland-Systemic.pdf