MD 318 heads east as Preston Road, a two-lane undivided road that intersects Langrell Road and Beulah Road a short distance east of its western terminus. Langrell Road is unsigned MD 817B, which follows the county line west to a dead end at Hunting Creek.
MD 318 runs northeast as Preston Road, a two-lane road that intersects with Langrell Road and Beulah Road nearby its western endpoint. Langrell Road is a local designation of MD 817B, which extends along the county line west until it reaches a dead end at Hunting Creek.