Capacity Characteristics of Urban Road Routes and Networks

While there have been a lot of studies on traffic capacity of roadway/road sections, very little work have been done on the traffic capacity of urban routes and road networks. 

Thus, this study focuses on the analysis of different concepts to define the route and network capacity and the main factors affecting them. 

In the study, computer simulation experiments were designed considering different types of routes and networks and the representative composite of roadway, traffic and control conditions on the roads in the developing countries. Several experiments were conducted by changing major parameters of roadway, traffic and control conditions in all types of routes and networks with the use of UTEM (Urban Traffic and Environmental analysis Model). Statistical analyses of simulation results were then performed to find the significance of difference between route types, network types, different concepts and different factors. In addition, regression analyses were performed to find the relationship between capacity and major factors. 

Results of the route capacity analyses indicate that there are differences in capacities based on bottleneck, route travel and route service concepts and the capacity based on route service concept is higher and more consistent. In case of network capacity, there seems to be no significant difference in capacities between network service and max-flow min-cut concepts in networks with one origin and one destination. For networks with many origins and destinations, only network service concept could be used in the experiments. 

Furthermore, it appears that route shape types as well as some major parameters of roadway, traffic and control conditions such as number of lanes on intersection approach sections, g/c ratio have significant effects on route capacity. In case of network, network types and some major parameters of roadway, traffic and control conditions as number of lanes on intersection approach sections, proportion of big vehicles, g/c ratio seemed to have significant effect on network capacity. 

These findings of urban route and network capacity analyses can be useful measures to design and manage urban routes and networks of developing countries.

In addition, this study can provide the basis for further studies on route and network capacity.