In order to utilize the spatial resources of the signalized intersections efficiently,based on the concept of integrated use of vehicular lanes,a design model was proposed using a special width approach lane which is combined by two narrow lanes.A capacity calculation model was established based on the probability distribution analysis of passenger cars traveling alongside each other.The precision of the model was tested by VISSIM simulation.Extensive numerical analyses were conducted to evaluate the performance of the proposed design and the results were compared with those of the conventional vehicular lane design.The results show that the special width lane design could increase the capacity of a vehicular lane.The improvement is negatively correlated with the heavy vehicles percentage and the proportion of the vehicles only permitted to drive on one lane of the narrow lane pair,and is positively correlated with the proportion of the vehicles permitted to drive on both lanes of the narrow lane pair.The greatest improvement achieves by as much as 75% in our examples.Moreover,in general,an optimization objective of 10% capacity enhancement could be achieved when the heavy vehicles percentage is lower than 30%.