Final Scope

Transportation agencies build and operate escape ramps to allow heavy vehicles that cannot maintain safe speeds on steep downgrades to safely exit the highway before losing control and crashing. Escape ramps involve important design choices specific to roadway, terrain, and vehicle characteristics. Some escape ramps use upward-sloping beds of loose aggregate to slow the vehicles, while others employ passive or active mechanical devices such as cables to retard their motion. The use of escape ramps also requires operational choices. Some agencies use intelligent transportation technologies to detect trucks that are exceeding or may soon exceed speeds appropriate for the vehicle and the location, and to warn drivers of the need and means to exit the roadway.

Because design and operations practices vary significantly among locations and agencies, no common design standards or recommended practices exist. Brake failures on heavy vehicles descending steep grades often result in serious crashes and fatalities.

The objective of this synthesis is to document practices used by state departments of transportation (DOTs) to design and operate facilities to detect, guide, and capture out-of-control vehicles travelling on steep downgrades.

Information to be gathered includes (but is not limited to):

• Prevalence and extent of escape ramp use;
• Policies and criteria for justifying and placing escape ramps;
• Established design criteria (e.g., types of ramps used, materials, dimensions, geometric, rehabilitation of existing ramps, accommodation of hazmat);
• Methods, including intelligent technologies, for detecting heavy vehicles that are already driving at uncontrollable speed or are in danger of doing so;
• Methods used to inform drivers of endangered vehicles of the availability and location of escape ramps and how to access them (e.g., signage, striping, lighting, in cab communication);
• How state DOTs incorporate escape ramps into information, education, and outreach provided to the public and  trucking industry (e.g., traveler information systems, published documents, oversize and overweight vehicle permitting systems, preventing and enforcing unauthorized use of escape ramps; driver education manuals);
• How state DOTs incorporate truck escape ramps in the planning of future improvements, construction projects, or programs (e.g., permitting of oversize and overweight vehicles);
• Maintenance practices (e.g., grooming and replacing materials, hazmat cleanup, truck removal, seasonal maintenance);
• Performance metrics; and
• Opportunities identified by state DOTs for development or refinement of practice.

Information will be gathered through a literature review, a survey of state DOTs, and follow- up interviews with selected agencies for the development of case examples. Information gaps and suggestions for research to address those gaps will be identified.

Information Sources (Partial):

• Truck Escape Ramps, NCHRP Synthesis of Highway Practice, Issue 178, 1992, 62 p. This synthesis was comprehensive when performed 30 years ago, before prevalent adoption of mechanical capture devices and intelligent detection and warning technology.
• Alternative Arresting System Design for Truck Escape Ramps, International Journal of Crashworthiness, Volume 23, Issue 6, 2018, pp 618-626.
• Determining the Optimal Location for Truck Escape Ramp in the Vicinity of Expressway Tunnels in Mountainous Areas, Transportation Research Board 97th Annual Meeting, 2018, 15p.
• Design for Approach Road of Truck Escape Ramp, Third International Conference on Transportation Engineering (ICTE), 2011, pp 2725-2730.
• Connecticut Department of Transportation's Truck Escape Ramp (TER) - Avon, CT. 4th International Symposium on Highway Geometric Design, 2010, 13p.
• Evaluation of Truck Arrester Beds in Colorado, 2008, 46p.
• The Design of Truck Escape Ramps, 12th World Congress on Intelligent Transport Systems, 2005, 8p.
• Development of a New Concept in Emergency Truck Escape Ramp Design, VTI Rapport, Issue 380A PT1, 1992, p. 193-214
• A Review of the Dragnet Vehicle Arresting System as Applied to Runaway Truck Escape Ramps. Final Report, 1991, 21p.
• Recommended Practice: Truck Escape Ramps, 1989, 19p.