Mehrtash Soltani

Analysis of developed transition road safety barrier systems

Road safety barriers protect vehicles from roadside hazards by redirecting errant vehicles in a safe manner as well as providing high levels of safety during and after impact. This paper focused on transition safety barrier systems which were located at the point of attachment between a bridge and roadside barriers. The aim of this study was to provide an overview of the behavior of transition systems located at upstream bridge rail with different designs and performance levels. Design factors such as occupant risk and vehicle trajectory for different systems were collected and compared. To achieve this aim a comprehensive database was developed using previous studies. The comparison showed that Test 3-21, which is conducted by impacting a pickup truck with speed of 100 km/h and angle of 25° to transition system, was the most severe test. Occupant impact velocity and ridedown acceleration for heavy vehicles were lower than the amounts for passenger cars and pickup trucks, and in most cases higher occupant lateral impact ridedown acceleration was observed on vehicles subjected to higher levels of damage. The best transition system was selected to give optimum performance which reduced occupant risk factors using the similar crashes in accordance with Test 3-21.

The safety performance of guardrail systems: review and analysis of crash tests data

The last decade has witnessed an increased number of vehicles and increased vehicle speed on roads such that the frequency and severity of run-off roadway accidents has increased dramatically. Evaluation of guardrail system performance as an element of providing a safe environment for vehicles and to reduce occupant injuries is deemed to be vital issue. Hence, this paper is going to assess deflection and vehicle trajectory of current guardrail systems. For this purpose, the results of full-scale crash tests for different types of guardrail system are collected from previous crash tests available in the literature. The results showed that for Test 3–11 (according to NCHRP Report 350) with similar post spacing (1905 mm), the trend of vehicle exit speed declined while guardrail maximum permanent deflection increased. In addition, among all system types, guardrail with curb and Thrie-beam guardrail systems were subjected to the lowest amount of deflection although Thrie-beam guardrail was subjected to higher average values for both vehicle exit speed and exit angle. Further, weak-post guardrail system showed to have the highest maximum dynamic and permanent deformation compared to other systems whereas it caused the lowest exit angle to the vehicles.

Crashworthiness of G4(2W) guardrail system: a finite element parametric study

ABSTRACT In recent years, vehicle demographics have changed to include a relatively large proportion of light trucks, such as pickups, vans and sport-utility vehicles. It is found that several types of guardrail systems, including the G4(2W) guardrail system, are unable to redirect the pickup trucks to roadway safely. Therefore, in this study, several options are considered; they include improving the splice connections and adjusting the guardrail height and the post spacing to improve the performance of this system. The G4(2W) guardrail system is modelled in LS-DYNA and validated with a previous full-scale crash test conducted by the Texas A&M Transportation Institute. A parametric study based on the results of the LS-DYNA crash simulation according to Length of Need test 3-11 and 3-10 is conducted to investigate key factors of guardrail systems, including the splice configuration, the post spacing and the guardrail height. The purpose of this study is to find a model that satisfies the requirements of Test Level 3 outlined in Manual for Assessing Safety Hardware (MASH)s criteria.