Research On Access Problem Of Suburban First-grade Highway

With the continuous advance of urban-rural balance, the economy between urban and rural areas grows in a great extent, and suburban highway plays an important part in it. In suburban highway constraction and land use beside roads, access is more and more become the key factor of arterial sevice level. Since there is no explicit design criterion and guide for road accesses, leading accesses disorder construction and anarchism. At the present time, such problems are serious, especially suburban first-grade higway, called"devil road". These accesses endanger people's life and possession., and attract many government's attention. Hence, many highway diractors and research centers take measures to treat accesses, such as closing accesses, setting traffic safety facilities, road safety education and so on. However, these treatments don't concern about people's travel convenience, and causer traffic accident still rising higher.The article was based on two objects"traffic safety"and"operation efficient", which put forward accesses improving countermeasure for suburban first-grade highway. Firstly, through consulting related research at home and abroad and field research, analysing accident cause related to highway accesses. The suburban first-grade highway accesses were classfied based on field survey data and traffic statistic rule, and were demostrated reasonable by single factor analysis method of mathematical statistics. Secondly, the article researched the rule of"traffic safety"and"operation efficient"affected by access element facotrs, including plane factors,lengthwise section factors and cross section factors, and found the relationship between safety and efficent by two reprentive index"accident rate"&"travel delay". Considering access spacing was a key factor enfluening travelling, three kind minimum spacing model(incluing equidirection- al accesses,opposite accesses and spacing between access and grade crossing) was put forward based on protecting main lane travalling,access travelling efficient and safely travelling apparent distance. Finally, specific improving countermeasures (for example derectional travelling median, right-of-way regulation, turning drivery division, locating frontage road and auxiliary road) were generalized for various accesses. In addition, vissim simulaiton sofeware was used to appraise before and after accesses improving of a case study, and the result showed that accesses improving coutermeasures were reasonable.