Assessment of the Effectiveness of Different Safety Measures at Tunnel Lay-Bys and Portals to Protect Occupants in Passenger Cars

Tunnel portals and tunnel lay-bys are hazardous spots for road users. Different infrastructure safety measures are in use, but the protection level is not known. In this study the following safety measures for reducing the injury risk are investigated: angular positioned 4 m and 8 m concrete barrier, crash cushion Alpina F1-50 and Alpina crash cushion. A passenger car equipped with a data acquisition unit is accelerated to 100 km/h and impacts the safety measure. The assessment of the latter is based on the EN 1317 criteria, specifically the Acceleration Severity Index (ASI), Theoretical Head Impact Velocity (THIV). Further assessment criteria are related to intrusions into the passenger compartment and post-crash motion. The best result in terms of ASI and THIV was achieved by the 8 m (ASI: 1.6, THIV: 30 km/h) concrete barrier. The crash cushion Alpina showed good results for the ASI (1.8) but the THIV (57 km/h) was less satisfactory, while the angular positioned 4 m concrete barrier (ASI: 2.9, THIV: 53 km/h) and the crash cushion Alpina F1-50 (ASI: 3.3, THIV: 74 km/h) performed worst. Even though some of the measures showed good results, no protection measure tested currently complies with all the assessment criteria used.