BASICS OF CONCRETE BARRIERS

When most people think of concrete barriers, they think of the New Jersey Concrete Safety Shape Barrier (NJ-shape or Jersey barriers). The key design parameter for a safety shape profile is the distance from the ground to the slope break point, because this determines how much the suspension will be compressed. For the NJ-shape, this distance is 330 mm (13 in.). A parametric study of various profile configurations that were labeled A-F showed the F performed distinctly better than the NJ-shape. These computer simulation results were confirmed by a series of full-scale crash tests. However, the F-shape was not widely used, because the states were well-satisfied with the NJ-shape, which also met the crash-test criteria. Higher concrete barriers are sometimes used as truck barriers and to provide an integral glare screen on concrete median barriers (CMBs). The New Jersey Turnpike Authority has crash-tested and developed a 1,070-mm (42-in.) CMB that can safely contain and redirect tractor-trailers to an upright position. Vertical concrete parapet walls do not have this energy management feature, but crash tests have demonstrated that they can perform acceptably as traffic barriers. The need to have a single-slope barrier profile that has more consistent performance than a vertical-face concrete wall led to the development of constant-slope barriers. Portable concrete barriers have greatly improved safety in construction work zones. Each of these barrier types fills a niche and helps meet the needs of highway agencies that select, design, and locate traffic barriers. In terms of safety performance, the 1,070-mm (42-in.) F-shape is currently the best technology. The F-shape profile is clearly superior to the NJ-shape and is gradually being used by more states for both portable and permanent concrete barriers.

Language

  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00790632
  • Record Type: Publication
  • Files: TRIS, ATRI, USDOT
  • Created Date: Apr 10 2000 12:00AM