No one would want to attempt to traverse the City of Angels by hiking cross-country or driving the slow, stoplight-strewn surface roads;instead travelers take the freeway.

• 有个不错的比喻是城市里的高架道路，要横越整个市区时，人们不会想要步行或慢慢开在到处都是红绿灯的平面道路，而会选择高架道路。