一、两种公路路线设计理论六十年代以前,在公路路线设计中,世界上大多数国家采用“极限值”设计理论。该理论的特点是,每一级公路的每一种地形区,规定一个设计速度;根据此设计速度规定出一系列设计极限技术指标(例如,最小半径、最大纵坡、最短视距等);路 One, two kinds of highway route design theory Before the sixties, in the route route design, most countries in the world adopt the “limit value” design theory. The theory is characterized by a design speed for each type of terrain at each level of highway; a set of design limit specifications (eg, minimum radius, maximum longitudinal slope, minimum viewing distance, etc.) are specified based on the design speed; road