Desire line is an informal path that pedestrians prefer to take to get from one location to another rather than using a sidewalk or other official route. 

“期望路线”指的是行人从A地到B地选择走的非正式道路，而不是走人行道或者其他的正式道路。

Desire lines (or "natural desire lines," as they're also called) are those well-worn ribbons of dirt that you see cutting across a patch of grass, often with nearby sidewalks -- particularly those that offer a less direct route -- ignored. 

你在草地上看到的人们踩出的一条条小路就是期望路线（也称为自然期望路线），附近的人行道常常被人们忽视，特别是那些绕路的人行道。