Performance of Longitudinal Barriers on Curved, Superelevated Roadway Sections

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 894: Performance of Longitudinal Barriers on Curved, Superelevated Roadway Sections presents guidance on designing, selecting, and installing longitudinal traffic barriers for curved, superelevated roadways for possible incorporation in the American Association of State Highway and Transportation Officials (AASHTO) Roadside Design Guide.

Curved, high-speed roadways are usually superelevated to make the curved roadway easier for vehicles to navigate. Several potential concerns and uncertainties arise when longitudinal barriers are installed on curved, superelevated roadway sections (CSRS). Roadway curvature increases the angle of impact of a vehicle with respect to the barrier. This angle increase can cause an increase in impact loading that may potentially exceed the capacity of barriers designed for impacts along tangent roadway sections. Measures of occupant risk may also increase in magnitude.

Research related to development of NCHRP Research Report 894 encompassed extensive vehicle dynamics and finite element analyses of vehicle-barrier impacts on CSRS. The analyses were conducted for several different vehicle and barrier types, and for a range of roadway curvature and superelevation; shoulder width and angle; roadside slope; and barrier orientation and placement. The results of the computer analyses were validated by crash tests at the FHWA’s FOIL with full-size extended-cab pickup trucks impacting W-beam guardrail on CSRS.

The report fully documents the research in the following five appendices:
* Appendix A: State DOT Survey Instrument and Instructions;
* Appendix B: Vehicle Dynamics Simulation Results;
* Appendix C: Finite Element Model Validations;
* Appendix D: Finite Element Simulation Results; and
* Appendix E: Full-Scale Crash Testing Report