Title

Transition from Guardrail to Concrete Bridge Rail for Low-Speed Roadways

Authors

Roger P. Bligh

Document Type

Journal Article

Publication Date

2005

Subject Area

planning - service rationalisation, planning - standards, mode - rail

Keywords

Savings, NCHRP Report 350, Low speed roads, Low cost options, Impact tests, Guardrail transition sections, Design standards, Crash tests, Collision tests

Abstract

In recent years, many state departments of transportation have had to modify their approach guardrail-to-concrete bridge rail transition systems to comply with the testing requirements of NCHRP Report 350. Generally, these transition systems are designed and tested for use on high-speed roadways. Because no national transition designs have been developed and tested for lower-speed conditions, the same transition standard is typically applied to all roadways regardless of speed. The new transition designs represent a significant increase in installation cost and complexity over some previous designs that were acceptable under NCHRP Report 230. Thus, it may be cost-prohibitive to require use of the same design on all roadways. The purpose of this research was to develop a guardrail-to-concrete bridge rail transition that is suitable for use on lower-speed roadways and that is less expensive and complex than current designs for high-speed roadways. A low-cost transition was successfully evaluated under NCHRP Report 350 Test Level 2 (TL-2) impact conditions. It is considered suitable for use on roadways that have traffic conditions appropriate for the use of TL-2 safety hardware. Use of this system provides significant savings in material and installation cost compared with high-speed (i.e., TL-3) transitions.