Ridgeways are a particular type of ancient road that exploits the hard surface of hilltop ridges for use as unpaved, zero-maintenance roads, though they often have the disadvantage of steeper gradients along their courses, and sometimes quite narrow widths. Before the advent of turnpikes or toll roads, ridgeway trails continued to provide the firmest and safest cart tracks. They are generally an opposite to level, valley-bottom, paved roads, which require engineering work to shore up and maintain. Unmaintained valley routes may require greater travelling distances than ridgeways.