Study On Access Optimal Design Forurban Residential Area

With the continuous advance of urbanization process,the large residential area becomes more and more popular which brings the city huge traffic pressures.As the link between inside and outside traffic of the residential area,the accesses,especially the vehicle accesses,are crucial to ensure the vehicle travel,ease traffic congestion,improve the transportation efficiency and guarantee traffic safety.In this study,the residential area of Harbin North Spring City was taken as example.The vehicle access optional design was researched from the aspect of traffic demand and access spacing after analyzing of the exiting problems of the residential area.This study tried to optimize the layout of vehicle accesses and minimize the disruption of residential area to urban traffic system.Firstly,the most common problems for residential areas were pointed out from the aspects of traffic organization and management of vehicle access based on the survey and analysis of traffic conditions and accesses,such as roadside illegal parking,insufficient parking spaces in the residential area,lack of special lanes,controversial number of accesses and unreasonable access spacing.Then,by analyzing the characteristics of traffic flow and vehicle driving in the access area,the capacity model based on capacity with base conditions and modification factors was proposed.The capacity with base conditions and the 6 modification factors including the lane width,proportion of oversize vehicle,the interference of pedestrian and roadside environment were all determined.After that,the accesses' capacities of the residential area were calculated and the numbers of accesses for the near-future and long term were determined according to traffic demand.At the same time,the contributing factors influencing access spacing were analyze and the principles for determining access spacing were also developed.Base on traffic safety and transportation efficiency,the access spacing models for same-side and opposite accesses were all established,as well as the influencing area model of cross intersections.Then,the minimum space of accesses was determined.Lastly,the process of access layout planning and constraints were presented and the layout schemes for near-future and long term were provided.The fuzzy comprehensive evaluation method was introduced to evaluate the two schemes from the aspects of road characteristics,coordination,characteristics of land use and drivers' characteristics.Finally,the traffic organization measures for accesses,road sections and areas were presented to enhance the transportation efficiency.The results showed that the capacity for single exit(entrance)was from 263 pcu/h to 293pcu/h(from 286pcu/h to 320pcu/h).The current 8 accesses could meet the near-future traffic demand,but a new access should be opened in the future considering the long term demand.The space for the same-side accesses was from 69 m to 72 m and the space for the opposite accesses was from 84 m to 88 m.The evaluation results showed that the access layout schemes for the near-future and long term were good and excellent,respectively.