Guidelines for Positive Barrier Use in Construction Zones

The need for positive barriers in construction zones is now based on individual judgment, and there is an expressed need for objective barrier placement criteria. The number, diversity, and variability of factors that affect barrier need within a work zone eliminate the possibility of development of a set of totally objective guidelines appropriate for any given circumstance. In an effort to develop procedures for determining barrier need at a given site, a computer program, which determines barrier warrants based on a benefit-cost algorithm, was developed. This program was adapted for use on microcomputers with a user friendly system that greatly simplifies its use. Further, a set of use guidelines for portable concrete barriers ( PCBs) was developed for typical work zone sites through the application of the benefit-cost computer program. Barrier end treatment use guidelines were also developed with the computer program. End treatments studied included flaring the barrier away from the travelway and two crash cushions. The optimum flare rate for flared end treatments was found to be 10:1. Crash cushion end treatments were found to be cost beneficial relative to flared end treatments only at extremely high traffic volumes.