Barriers In Construction Zones PDF Download

On August 15, 1975, the National Transportation Safety Board submitted a number of recommendations to the Administrator of the Federal Highway Administration and the Governor of Virginia regarding safety practices in the construction zone of I-495 in Northern Virginia. Subsequently, officials of the Virginia Department of Highways and Transportation requested that the Virginia Highway and Transportation Research Council evaluate the recommendations that pertained to the use of timber barricades. The scope of the evaluation included (1) a survey of the literature on the subject of legal requirements for temporary barrier systems in highway construction zones, (2) an analysis of crash data on I-495 for periods before and during construction, and (3) an analysis of the technical operational, and economic feasibility of the timber barricade and the precast concrete traffic barrier. The evaluation has revealed that there is no adequate national standard for traffic control in construction zones. Consequently, as in the case studied here, engineers are left to exercise their judgment as to the proper use and placement of delineators, barricades and other channelizing devices, and traffic barriers. The evaluation also has indicated that the frequency of accident occurrence during construction on I-495 was approximately 119% higher than before construction. Of the reported crashes during construction, 52.5% involved vehicle contact with the timber barricades. Among barricade-involved crashes, 73.5% involved vehicles which straddled or penetrated the barricades. Thus, in service on the I-495 site the timber barricades have proved, to be ineffective as positive barriers. The precast concrete traffic barrier was found to cost approximately $5.60 per linear foot more than the timber barricade employed on I-495. Testing of the precast concrete traffic barrier in a freeway construction zone is recommended prior to its general use in the Commonwealth.