After exiting the large commercial developments near U.S. 101, Route 152 consists of a single lane in each direction, with narrow shoulders, rain ditches on either side of the road, no center dividers, and posted speed limit of 55 mph (89 km/h), making it prone to head-on collisions. Headlights are required at all times along this portion. This segment is a significant bottleneck for traffic traveling along Route 152 between the San Francisco Bay area and the Central Valley. Upon reaching Route 156 near Hollister, the road expands to two lanes in each direction, and climbs and curves along the valley of Pacheco Creek into the mountains of the Diablo Range, crossing them through the Pacheco Pass into the San Joaquin Valley.