Road side safety hardware: Current status and future outlook
Authors: Abu-Odeh Akram 
Published: November 2015

As an integral part of engineering safer roads, road side safety devices passively interact with errant vehicles to redirect them safely back to the road or bring them to a safe and controlled stop. These devices take the form of crash cushions, cable barriers, concrete barriers, steel barriers, guard rails, guardrail terminals and others. Placement criteria and warrants are established in the AASHTO Road Side Design Guide (1). However, before those devices are placed on the roadways, they have to be evaluated under objective test conditions.. Given that possible combinations of impact speeds, impact angles, vehicle characteristics and roadway characteristics are infinite, it is impossible to design roadside safety hardware for all those combination. Thus a “Practical Worse Case” philosophy derived from crash data analyses is followed to determine such impact conditions. In the USA, the evaluation methodologies are established in the National Cooperative Highway Research Program (NCHRP) Report 350 (2) which is now superseded by Manual for Assessing Safety Hardware (MASH) guidelines (3). In Europe a comparable set of guideline (EN 1317) is used to evaluate road safety devices under vehicular impact. Many roadway authorities around the world adopt either EN 1317 or NCHRP Report 350 with some modifications to incorporate local requirements.
In the early parts of this presentation demonstrate testing conditions and criteria for quantifying the device as crashworthy under NCHRP Report 350 and MASH for some of the common road safety devices. The most common test conditions are explained in details. The key criteria of acceptance shall be presented for the most common test conditions.
State of the art nonlinear finite element methodology has been gaining tractions in designing and enhancing the safety of vehicles and roadside devices. This presentation will highlight roadside safety hardware (4, 5, and 6) that was designed through extensive simulation process and had subsequent successful crash test per the latest MASH guidelines.

REFERENCES
1. America Association of State Highway and Transportation Officials , Roadside Design Guide, 4th Edition, AASHTO, 2011.
2. Ross, H.E., D.L. Sicking, R.A. Zimmer, and J.D. Michie, Recommended Procedures for the Evaluation of Highway Features, NCHRP Report No. 350, 1993, Transportation Research Board: Washington, D.C.
3. AASHTO, Manual for Assessing Safety Hardware, 2009, American Association of State Highway and Transportation Officials: Washington, D.C.
4. Abu-Odeh, K.M. McCaskey, R.P. Bligh, W.L. Menges, D.L. Kuhn. Crash Test and MASH TL-3 Evaluation of the TxDOT Short Radius Guardrail. Test Report. 0-6711-1. Project No. 0-6711. Texas A&M Transportation Institute, College Station, TX. March 2015

5. A. Abu-Odeh, R.P. Bligh, M.L. Mason, W.L. Menges. Development and Evaluation of a MASH TL-3 31-Inch W-Beam Median Barrier. 9-1002-12-8. Texas A&M Transportation Institute, College Station, TX. January 2014.

6. A. Abu-Odeh, W.F. Williams, M. Ferdous, M.T. Spencer, R.P. Bligh, W.L. Menges. Safety and Integrity of Median Barrier-Mounted Hardware. 0-6646-S. Texas A&M Transportation Institute, College Station, TX. 2013.