Freeway Workzone Capacity and Associated Economic Concepts

Abstract

Like many other transportation agencies, the Ministry of Transportation Ontario (MTO) is also using the same work zone closure strategies and standards that it has used for decades. However, the lane closure strategies should incorporate the impacts of construction duration and inconvenience to the road users and find the balance where users face minimal inconvenience while contractors have the appropriate amount of time to finish the work and produce a high quality product. In-order to evaluate and assess the appropriate time for lane closures, it is important to estimate the capacity of the lanes. The capacity estimates can help in determining the optimized time for lane closures to minimize the user delays while providing sufficient time for contractors to achieve the desired productivity and quality of work. There are different models, computer Software and wide variety of studies to evaluate and estimate the Workzone Capacity and associated User Delay Costs at workzones. These costs are primarily affected by traffic flows, vehicle speeds, and work zone capacities.

In-view of the above, this study is designed to estimate freeway capacity of construction workzones and discuss the associated user delay costs and economic issues. For this study, the capacity at the work zones was measured as the mean queue discharge flow rate during forced-flow conditions. Forced-flow conditions were defined as congested conditions during which a sustained queue formed. There are several studies and approaches for collecting traffic volume data for estimating workzone capacity. For this study, it was decided to utilize a manual counting method for volume data. This would help provide the visual confirmation of queuing and intensity of work activity at workzones. Six sites located in Southern Ontario, were selected for this study. The data from these sites is used to develop a mathematical model for estimating workzone capacity for Ontario.