Access to US 4 eastbound is facilitated by nearby NH 155A, which rejoins its parent and runs east (signed south) to its own interchange with US 4.

NH 155 continues north along the western edge of Durham and the eastern part of Madbury before crossing into the city of Dover.

New Hampshire Route 155A is a three-quarter loop of NH 155, running 3.699 miles (5.953 km) in the towns of Lee and Durham.

NH 155A runs into the western part of the UNH campus until reaching Main Street.

The highway turns left on Main Street heading away from the center of campus and interchanges with US 4.