A frontage road (also access road, feeder, service drive, service road, outer road, and especially surface road) is a non-limited access road running parallel to a higher-speed road, usually a freeway, and feeding it at appropriate points of access (interchanges). In many cases, the frontage road is a former highway already in existence when the limited access road was built. In other cases they may be built prior to construction of the highway. In urban areas, frontage roads are frequently one way roads when they exist on both sides of a highway. In more rural ones, roads are typically two-way.

Frontage roads provide access to homes and businesses which would be cut off by a limited access road and connect these locations with roads which have direct access to the main highway. Frontage roads give indirect access to abutting property along a freeway, either preventing the commercial disruption of an urban area that the freeway traverses or allowing commercial development of abutting property. At times, they add to the cost of building an expressway due to costs of land acquisition and the costs of paving and maintenance. However, the benefits of nearby real estate can more than offset the cost of building the frontage roads. Furthermore, a frontage road may be a part of an older highway, so the expense of building a frontage road may be slight. Conversely, the existence of a frontage road can increase traffic on the main road and be a catalyst for development; hence there is sometimes an explicit decision made to not build a frontage road.

A backage road is a similar concept, but lies on the other side of the land parcels that abut the frontage road. It serves mainly to provide access to those parcels without using the frontage road.