FDOT Sponsored Research, BDV32-977-03 (Cost-share project for STRIDE Center)
Authors: Lily Elefteriadou, Ph.D., Alexandra Kondyli, Ph.D., Bryan St. George (graduate student)
Report completed:  September 2014
[final report]

Transportation engineers use the Highway Capacity Manual (HCM 2010) to estimate the amount of vehicles that freeways can tolerate without becoming oversaturated. Field measurements in Florida have shown measured capacities are actually lower than the recommended values in the HCM 2010, and recently, it has been found that maximum freeway throughput could differ between undersaturated and over saturated conditions. This so called “two-capacity” phenomenon is not currently considered in the HCM 2010. In order to provide recommended values specific for Florida, the research team comprised of Dr. Lily Elefteriadou, Dr. Alexandra Kondyli and graduate student Bryan St. George, collected data at several urban and rural freeway and multilane locations in Florida in order to capture capacity flows, and to provide recommended capacity values before and after the initiation of oversaturation. Urban freeway data were obtained through Florida’s STEWARD database at various types of bottlenecks including merge junctions, weaving segments, as well as geometric bottlenecks (lane drops), while the rural freeway and multilane highway data were obtained from the permanent count stations of FDOT. In conclusion, the researchers provide recommended capacity values as a function of the number of lanes and the segment type for both urban and rural locations. They also proposed a revised density threshold for defining Level of Service at various bottlenecks as a function of the recommended capacity values. This project was sponsored by the Florida Department of Transportation.

For more information, contact: Dr. Lily Elefteriadiou at elefter@ce.ufl.edu.