Investigating the influence on safety of retrofitting Italian motorways with barriers meeting a new EU standard

摘要

A new European Union (EU) regulation for safety barriers, which is based on performance,has encouraged agencies to perform an upgrade of the old barriers, with the expectation thatthere will be safety benefits at the retrofitted sites. The new class of barriers was designedand installed in compliance with the (European Norm) EN 1317 standards for Road RestraintSystems created in 1998, which lays down common requirements for the testing andcertification of road restraint systems in all countries of the European Committee forStandardization (CEN). Both the older and new barriers are made of steel and are installed insuch a way as to avoid vehicle intrusion, but the older ones are thought to be only effective atlow speeds and low angles of impact. The new standard seeks to remedy this by providingbetter protection at higher speeds. The paper seeks to quantify the effect on the frequency offatal+injury crashes of retrofitting motorways with barriers meeting the new standards, byperforming an empirical Bayes before-after analysis based on data from the A18 Messina-Catania motorway in Italy. The results suggest a safety benefit, which, although statisticallyinsignificant, is enough to recommend that the retrofits are cost-effective and shouldcontinue. However, the sample size needs to be increased in order to develop a statisticallyrobust crash modification factor.