Construction zones, though required for infrastructure maintenance, have become congestion choke points on most highway systems in the US. The congestion may create potentially unsafe driving conditions for approaching motorists that do not expect queue there. Managing the growth and dissipation of vehicular queue upstream and within work zones can help reduce congestion and improve traffic safety. However, critical issues are how to determine the extent of queue and congestion accurately, as well as how to best use that information in managing the adverse effects of queue. This study investigated some of the issues in capacity, queue length, and delay estimation in work zones. In particular, the current methods for analyzing congestion in work zones are examined. Further requirements to improve the accuracy of analysis are identified and discussed. The effect of large gaps between vehicles on capacity measurement is determined using field data. Alternative methods for computing work zone capacity were developed. Furthermore, two types of moving queue are studied: 1) intermittent moving queue, 2) continuous moving queue. The characteristics of each type of queue are studied using field data. A methodology to estimate intermittent queue length and delay is proposed. The study investigates continuous moving queue propagation and dissipation using shockwave theory. Also, formulations are developed to estimate continuous moving queue length and delay. (Author/publisher)
Abstract