title: Required length of guardrails before hazards.
abstract: One way to protect against impacts during run-off-road accidents with infrastructure is the use of guardrails. However, real-world accidents indicate that vehicles can leave the road and end up behind the guardrail. These vehicles have no possibility of returning to the lane. Vehicles often end up behind the guardrail because the length of the guardrails installed before hazards is too short; this can lead to a collision with a shielded hazard. To identify the basic speed for determining the necessary length of guardrails, we analyzed the speed at which vehicles leave the roadway from the ZEDATU (Zentrale Datenbank Tödlicher Unfälle) real-world accidents database. The required length of guardrail was considered the length that reduces vehicle speed at a maximum theoretically possible deceleration of 0.3g behind the barrier based on real-world road departure speed. To determine the desired length of a guardrail ahead of a hazard, we developed a relationship between guardrail length and the speed at which vehicles depart the roadway. If the initial elements are flared away from the carriageway, the required length will be reduced by up to an additional 30% The ZEDATU database analysis showed that extending the current length of guardrails to the evaluated required length would reduce the number of fatalities among occupants of vehicles striking bridge abutments by approximately eight percent.
authors.affiliation: Vehicle Safety Institute, Graz University of Technology, Inffeldgasse 11/2, 8010 Graz, Austria. Electronic address: ernst.tomasch@tugraz.at.
authors.forename: E
authors.initials: E
authors.lastname: Tomasch
authors.affiliation: Vehicle Safety Institute, Graz University of Technology, Inffeldgasse 11/2, 8010 Graz, Austria.
authors.forename: W
authors.initials: W
authors.lastname: Sinz
authors.affiliation: Vehicle Safety Institute, Graz University of Technology, Inffeldgasse 11/2, 8010 Graz, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Hoschopf
authors.affiliation: Vehicle Safety Institute, Graz University of Technology, Inffeldgasse 11/2, 8010 Graz, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Gobald
authors.affiliation: Vehicle Safety Institute, Graz University of Technology, Inffeldgasse 11/2, 8010 Graz, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Steffan
authors.affiliation: Nast Consulting ZT GmbH, Lindengasse 38, 1070 Wien, Austria.
authors.forename: B
authors.initials: B
authors.lastname: Nadler
authors.affiliation: Nast Consulting ZT GmbH, Lindengasse 38, 1070 Wien, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Nadler
authors.affiliation: Kuratorium für Verkehrssicherheit, Siebenbrunnengasse 21, 1050 Wien, Austria.
authors.forename: B
authors.initials: B
authors.lastname: Strnad
authors.affiliation: Kuratorium für Verkehrssicherheit, Siebenbrunnengasse 21, 1050 Wien, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Schneider
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D001317:Austria; D016208:Databases, Factual; D004779:Environment Design; D006801:Humans; D011482:Protective Devices / Q000592:standards* / Q000706:statistics & numerical data