Arterial signal synchronization is the most cost-effective method for reducing vehicle operating costs and controlling fuel emissions on the urban street network. From a modeling perspective this process requires the determination of optimum signal control parameters with the objective of minimizing system disutility or maximizing the progression bandwidth. Some compromise approaches have also been suggested. This work focuses on the bandwidth approach. The objective of this research was to develop a traffic model with a capability for simultaneously optimizing all signal control variables including left-turn treatment, including protected, permissive, or protected-permissive phasing. For evaluation purposes a four-intersection arterial was analyzed by using the proposed (ZMODEL) and an alternative PASSER-II bandwidth model. The TRANSYT-7F model was subsequently used to evaluate the signal settings. As a result of the added flexibility in left-turn control, the model generally produced lower system cycle lengths and wider bandwidths for the artery. On the other hand and on the basis of limited experiments, the overall system utility may actually degrade. The trade-off between bandwidth efficiency and delays (for artery and all movements) is clearly demonstrated.