Abstract: The building-block method is one of the curve-type designing methods based on alignment unit.When designing in-terchange ailgnment one canlay out the next unit if the information of the pre-existing unit such as coordinates,tangentazimuth and curature rad

Key words: curve-type design metheds, alignment unit, building-blocks method.

摘要： 积木法是一种以线元为核心的曲线型设计方法．立交线形设计时，已知前一单元终点的信息如坐标、切向或法向方位角、曲率半径等，在选定下一单元形式和其他有关信息的条件下，进行下一单元的设计．自始至终，一个单元接一个单元，如搭积木一样，完成整条匝道或主线的平面线形设计．本文主要介绍积木法的原理、方法与步骤．

关键词: 曲线型设计方法, 线元, 积木法