• October 11th, 2009

At the Alabama Department of Transportation (ALDOT), the tool used by traffic engineers to predict whether a queue will form at a freeway work zone is the Excel-based ―Lane Rental Model‖ developed at the Oklahoma Department of Transportation (OkDOT) and whose work zone capacity values are based on the 1994 Highway Capacity Manual (HCM, 1994). The scope of this project pertains only to the queue estimation worksheet of that spreadsheet tool, herein referred to as the OkDOT Baseline Version. This tool, based on input-output logic, is simple to understand and use. Preliminary testing of the OkDOT Baseline confirmed a tendency to overestimate queue length, and an opportunity to update the capacity estimation method while keeping the rest of the tool intact. Two other versions were created using the work zone lane capacity model of HCM 2000; the HCM 2000 Version uses work zone intensity effects of -160 to +160 passenger cars per hour per lane (pcphpl) as prescribed in HCM 2000. The second modified version uses work zone intensity penalties of -500 to 0 pcphpl, a modification based on recent literature, and is therefore called the HCM 2000 Hybrid Version.