Concrete crash barrier
A concrete barrier wall , concrete sliding wall or concrete guide wall , technically known as a concrete retention system , is a passive protective device ( retention system ) made of concrete on roads . It is produced either from precast concrete parts or in in-situ concrete using a sliding formwork. Concrete barriers are only anchored in the ground in exceptional cases. Usually they should give a little in order to reduce the braking acceleration of the impacting vehicle (and thus the occupants).
Effect in case of impact and accidents
With most concrete crash barrier systems, the in-situ concrete walls or protective walls made of prefabricated parts shift depending on the area of action by a few, but significant, centimeters if they are not backfilled. The length of the wall is stabilized by iron reinforcement so that it bulges as a whole piece. The breakthrough on the opposite lane is thus prevented. In front of massive obstacles, the walls can be designed to be free of displacement by clamping or backfilling.
The main effect of concrete barriers is to divert the impacting vehicle. The energy released on impact is largely passed on to the motor vehicle due to the limited flexibility of the system. When deflecting, however, there is the risk that the vehicle will tip over and be thrown into other lanes, where other cars will also be involved in the accident.
The clearance is referred to as the effective range (approximately 0.6 m to 3 m):
- Effective area = element width + displacement in the event of an impact
Concrete barriers can be replaced and set up relatively quickly after accidents - the concrete bodies themselves are sacrificial material in the sense of a crumple zone that absorbs the impact energy and are routinely disposed of after an accident.
To date, there is not a single restraint system in the world that gently and 100% safely brakes vehicles of all types that are coming off the road. Restraint systems have the task of preventing worse things - e.g. B. Head-on collisions in the median area, falls in the edge area over an embankment or bridge.
Due to doubts regarding the equivalence of concrete crash barriers in relation to modern steel protection systems for passenger vehicles, the Federal Highway Research Institute is now (2007) carrying out a comparative study focusing on the consequences of accidents. In Austria, these studies have been completed for a number of years and crash barriers are being completely replaced - initially on motorways and expressways, and increasingly also on trunk roads.
Construction methods
Jersey barrier
A distinction is made between double-sided and single-sided concrete barriers. The double-sided concrete protection wall serves as a single-row central protection and has a characteristic profile on both sides. Common profiles are the New Jersey profile , which has been around since 1959 or 1960, and the step profile . A one-sided concrete crash barrier only has the characteristic profile on the side facing the street. With the New Jersey profile , one half of the wall is 30 cm wide at the bottom and tapers to 12.5 cm at a height of 33 cm. The upper 44 or 78 cm high part then tapers again to 7.5 cm. This shape is intended to ensure that a vehicle that breaks out of the lane is first guided upwards on the lower part (deflection surface) of the wall and then steered back into the lane on the upper vertical (deflection surface) due to the resulting inclination . Due to the reinforcement in the upper part of the wall, usually as a continuous tie , the walls are so stable that trucks are prevented from breaking through the wall in this way, which is why their installation is often used today on bridges.
Shorter, movably connected components with a bead on top are used for machine offset around a lane .
Use on construction sites and other road construction
The walls made of prefabricated parts can also be erected as a curb as temporary protection in the course of road construction work. These are also not firmly connected to the subsurface. Directional strip separators can be set up quickly in the construction site and offer the same level of safety as the permanent installation.
As a concrete sluice , they are used to narrow a lane, for example to keep wide vehicles away from bottlenecks.
Concrete restraint systems are also increasingly being used in urban traffic management , for example in the braking areas at local entrances. Furthermore, they prove themselves in combination with adapted construction methods of noise barriers and replace any other glare protection device .
Road zipper
Especially in Canada, the United States and their suburbs and Australia, special concrete guide walls are used for variable lanes for rush hour traffic. They are also used on construction sites, for the first time in Austria for six months in 2016 and 2017 at a night construction site in the Stadlauer and Hirschstettner tunnels on the Vienna south-east bypass instead of the usual traffic cones . At night, one lane is blocked for construction work, safely separated by the guide walls and returned to traffic in the morning. The concrete parts are shorter than the usual, flexibly connected to each other and have a bulge on the top. A “ barrier transfer machine ” (also “zipper machine” or “ road zipper ”) grabs the elements on the bead while driving, lifts them up slightly and moves them one lane to the side via an S-shaped guide system inside. The road zipper does not need to be used to secure traffic or a mobile construction site, as it is protected from ongoing traffic by the protective wall, which it moves itself and clears the lane (s) in front of it. In left-hand traffic , the Road Zipper must be set up the wrong way round in order to operate safely. The forerunner was first used between 1984 and 1985. He was deployed on the Auckland Harbor Bridge in 1990; to Oahu in 1998 and to 15 other locations in the USA over the next 20 years. In 2012 he came to Sydney and 2017 to Austria.
Normalization
Restraint systems are tested and approved in Europe according to a uniform standard EN 1317 Restraint systems on roads .
In addition to the general national standards on restraint systems, the following apply:
- For Austria RVS 04/15/71 (03:47 PM) bridge equipment , vertical guidance systems, vehicle restraint systems made of concrete and metal
- For Germany, the guidelines for passive protection on roads through vehicle restraint systems (RPS) of the FGSV from 2009.
Court ruling
"The ASFINAG motorway company is jointly responsible (25%) for a fatal traffic accident (2007) on the Bischofshofen bypass (Pongau) because the concrete lane separator there was too weak (...) the Supreme Court ruled in June 2017." A 7, The 5-ton truck broke through the central concrete crash barrier on a driveway and collided with a car on the opposite direction, and both of its occupants died. A more massive wall would have been necessary for a permanent road separation at 80 km / h.
See also
Web links
- Cement data sheet (PDF; 170 kB)
- Brief version of the BASt report V 106 from 2003
- Info letter from the concrete protective wall lobby (PDF; 396 kB)
- Info letter from the steel guard rail lobby (PDF; 224 kB)
- Articles for and against. In: Rhein-Sieg-Anzeiger
Individual evidence
- ↑ Areas of action of concrete crash barriers
- ^ Westdeutsche Zeitung March 21, 2007
- ↑ Kurt Hellmich, Johann Stella, Erwin Stangl, Siegfried Piringer, Helmut Heimel, Joseph Plomer: Restraint systems on bridges in the start-up test . In: Federal Ministry for Transport, Innovation and Technology , Federal Road Administration (Hrsg.): Street research . tape 521 . Self-published, Vienna 2002 ( Information , Fraunhofer IRB [accessed on September 7, 2009] Distribution: Austrian Research Association for Roads and Transport).
- ↑ Zip fastener for construction sites. In: futurezone.at. November 16, 2015, accessed November 17, 2015 .
- ^ Initiative concrete protection wall (publisher): EN 1317 . Explanations. Cologne June 2003 ( tss-koeln.de [PDF; accessed September 7, 2009]). tss-koeln.de ( Memento of the original from July 23, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ BMVIT (ed.): Restraint systems on bridges - impact loads according to RVS 04/15/71 . ( bmvit.gv.at [PDF; accessed on January 21, 2011]).
- ↑ Concrete barrier too weak: ASFINAG sticks orf.at, 23 June 2017; accessed June 23, 2017.
