Impact of Lane Closures on Roadway Capacity: Development of a Two-Lane Work Zone Lane Closure Analysis Procedure (Part A)Author/Presenter: Washburn, Scott S.; Hiles, Thomas; Heaslip, Kevin
While there have been a number of studies conducted on roadway work zone operations, very few of them have focused on two-lane roadway work zones, where one lane is closed and traffic flow must alternate on one lane. These types of work zones usually rely on the use of flagging personnel to alternate the flow of traffic on the single open lane. Thus, the analysis of this type of work zone is quite different from that of multilane roadways. While a couple of analysis methods do exist for this type of work zone, there is no commonly accepted or nationally adopted method. The Florida Department of Transportation (FDOT) developed their own method, which is included in their Plans Preparation Manual (PPM). This method is fairly simple and considers a limited number of factors. Consequently, there is very limited range of field conditions for which this method will yield reasonably accurate results. Furthermore, the only output from the method is work zone capacity. The objective of this project was to develop an analysis procedure for two-lane roadway work zones (with a lane closure) that was more robust, both in terms of inputs and outputs, than the FDOT’s current PPM method. A custom microscopic simulation program was developed to generate the data used in the development of the models contained in the new analysis procedure. Specifically, models were developed to estimate work zone travel speed, saturation flow rate, queue delay, and queue length. The analysis procedure also employs calculation elements consistent with the analysis of signalized intersections. The analysis procedure has been implemented into an easy-to-use spreadsheet format.