The purpose of traffic barriers is to protect the traveling public as well as to provide a safe work zone for the construction crew on the side of the road. Design of the safe back distance has several implications. On the one hand, there is the issue of safety of the construction workers and the public. On the other hand, there is the issue of practicality and economic viability of highway construction projects. The North Carolina Department of Transportation (NCDOT) is currently in the process of developing its own traffic control design manual. The existing section on temporary traffic barriers requires calculating deflection of free standing barriers using an impact severity formula based on the Kinetic Energy principle. The design method, although approximate, is neither simple nor user friendly. Moreover, its applicability to the NCDOT and the Oregon Type F barriers, which the NCDOT plans to use, is very much questionable.
The objective of this research is to develop design aids, i.e., design charts and tables, for portable concrete barriers based on calibrated numerical analysis and rational design approach to be included in the new NCDOT traffic control design manual. Since both the NCDOT and the Oregon Type F barriers have been recently crash tested, only numerical analysis (and no crash test) is required for the design of both types of barriers. Once the physical impact problem is modeled and calibrated against the recent crash tests on both the NCDOT traffic barriers and the Oregon Type F traffic barriers, it can be used to determine the safe back distance as well as the length of need for free standing portable concrete barriers under different design conditions, including barrier type, design speed, vehicle mass, lane configuration, and roadway geometry, i.e., tangent or curved segments with different radii of curvature. The deliverable of the project is design aids for the NCDOT barriers and the Oregon Type F barriers for use in the NCDOT traffic control design manual. Benefits to the NCDOT may be realized as safety, cost-savings, and design efficiency on all roadway construction projects.
