Estimating Operational Impacts of Freeway Work Zones on Extended Facilities

This paper presents an approach to estimating the operational impacts of freeway work zones. The focus is on significant work zones on freeway corridors as defined by FHWA. The methodology is based on deterministic freeway capacity concepts described in the “Highway Capacity Manual” and allows the analyst to test impacts of a range of work zone configurations in an extended time—space domain. The focus on extended facilities refers to the analysis of multiple segments of various types, including basic freeway, ramp, and weaving segments. The cost-effective and time-efficient analysis approach can model effects of work zones such as lane closures, lower speed limits, capacity reduction, and the implicit effects of traffic diversion, peak reduction, and other intelligent transportation system strategies. Performance measures include total delay, queuing impacts, average running speed, and the potential to estimate user cost. The methodology focuses on a corridor-based analysis of work zones on freeways. It is not appropriate for network analysis, for long corridors, for signalized arterials, or for cases in which congestion on the arterial network significantly affects freeway operations. In these applications, a simulation-based analysis is more appropriate. However, the methodology presented in this paper is more cost-effective and less data intensive than simulation analysis and can readily be calibrated with local or regional data. This is a key advantage in challenging economic times, when agencies struggle to balance a constrained budget with the need to analyze multiple construction projects within their jurisdiction.