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

Scope: The number of fatalities on Austrian motorways and expressways has been decreasing in recent years. Tunnel portals or tunnel lay-bys that are not well protected are hazardous spots on the motorways and expressways. One person is killed each year on average by impacting the tunnel portal or the front end of a tunnel lay-by. Objective: A number of measures are currently available at tunnel lay-bys and portals (e.g. crash cushions, concrete barriers, guardrails, etc.) to protect occupants in passenger cars. No studies concerning the effectiveness of those measures, however, are yet available. The present research project intends to find the most effective protection measure for tunnel lay-bys and portals. The following safety measures are investigated: angular positioned 4 m concrete barrier, angular positioned 8 m concrete barrier, crash cushion Alpina F1-50 and the Alpina <prototype> crash cushion. Method: A passenger car equipped with a data acquisition unit is accelerated to 100 km/h and impacts the protection measure. The acceleration in the center of gravity is recorded and high speed videos are made of the test. The assessment of the protection measures is based on one single test for each measure. ASI and THIV are calculated according to EN 1317. Further assessment criterions are related to intrusions into the passenger compartment and post-crash motion. Results and conclusions: At the moment no protection measure tested met all the assessment criteria of EN 1317. The angular positioned 4 m concrete barrier as currently used in practice in tunnel lay-bys cannot be recommended. Protecting a tunnel lay-by using an angular positioned 8 m concrete barrier showed a similar protection level as the crash cushion Alpina F1-50. The severity indices ASI and THIV, however, are far above the thresholds in EN 1317. The crash cushion Alpina <prototype > showed the most promising results in the assessment. Further to the assessment criteria in the project defined further benchmark issues such as the on-site requirements (e.g. available space, etc.), maintenance, operational conditions, etc. the efficient measure should be taken into consideration.