城市互通立交匝道选型方法研究

立交的形式在很大程度上由左转匝道的形式所决定，在立交规划设计中，往往面临着对单一流向左转匝道的选型问题，而相关规范对此没有明确规定。文中以城市互通立交左转匝道为对象，运用Vissim建立仿真平台，探求半定向及环形左转匝道的适用性，从绕行距离、行程车速等方面给出评价，并以立交各流向流量之和最大为目标函数，以路段、分合流、交织区通行能力等作为约束条件，运用数学规划理论建立了一般立交通行能力计算模型。

Selection of Ramp Configuration for Expressway Interchanges

Expressway interchanges are typically characterized by the left turn ramps. Thus, the treatment of such ramps plays a key role in expressway interchange design. This subject has not been adequately addressed in the current design manual. This paper studies left-turn ramp design by focusing on the jughandle and cloverleaf configurations. Using the VISSIM simulation platform, this paper evaluates the effectiveness of the different types of designs as measured by the roadway length, travel speed, and flow rates. A mathematical model is developed to estimate the capacity of the interchange by considering link capacity and the geometric conditions at the weaving and diverging areas.