California State Route 4 - Route Description

Route Description

State Route 4 is part of the California Freeway and Expressway System and is eligible for the State Scenic Highway System. However, it is only a scenic highway as designated by Caltrans from a point east of Arnold to SR 89. SR 4 is also known as the John Muir Parkway from I-80 in Hercules to I-680 near Martinez, named for the environmentalist John Muir. The stretch through Franklin Canyon was once known as "Blood Alley."

SR 4, an east–west highway, begins in Hercules at San Pablo Avenue next to the Interstate 80 junction as part of John Muir Parkway. (The actual parkway extends a bit past the western terminus.) The road is an expressway between from its starting point until it approaches Martinez, at which point it becomes a full freeway (the California Delta Highway) passing Concord, Pittsburg, and Antioch. The John Muir National Historic Site, located directly north of Route 4 on Alhambra Avenue in Martinez. Also on Alhambra Avenue at SR 4 is the Franklin Canyon Adobe. BART tracks run in the median of the freeway from the Port Chicago Highway interchange in Concord to the Bailey Road interchange in Bay Point, where the line currently ends at the Pittsburg/Bay Point Station. Access to that station is provided by a pedestrian bridge crossing over the eastbound lanes of Highway 4. After Antioch, the freeway turns southward at its intersection with State Route 160, turning into a suburban and rural road bypassing the Bay Area's outermost eastern suburbs (Oakley and Brentwood); this section is also known as the John Marsh Heritage Highway.

Route 4 east continues to Stockton, where it briefly joins I-5 and then enters a separate freeway (known locally as the Crosstown Freeway) routing almost directly through downtown Stockton. The route then runs concurrent with State Route 99 before running eastward into the Sierra through Angels Camp, one of the richest quartz mining sections of the Mother Lode and home of "The Celebrated Jumping Frog of Calaveras County", and Calaveras Big Trees State Park. The route runs through the 8,050 ft (2,450 m). (2,454 m) Pacific Grade Summit on its way up to the 8,730 ft (2,660 m). (2,661 m) Ebbetts Pass (being Northern California's highest road) and ends at State Route 89 ten miles (16 km) west of Topaz Lake, on the California–Nevada border. The portion from Arnold to its terminus is designated the Ebbetts Pass Scenic Byway, which is eventually one lane.

Through the mountains, SR 4 is not suitable for large trucks, buses, or RVs, as it becomes very steep and narrow, with no center dividing line shortly after the Mount Reba Turnoff to Bear Valley Ski area, with tight switchbacks. The pass is not plowed for snow, and thus closes during the winter months often from November through as late as May. Thus, no passage between the Mount Reba Turnoff and Markleeville is possible. The western slope is plowed and rarely closes, even for a few hours, but often has chain restrictions during and immediately following storms, usually just east of Arnold. The eastern slope is not plowed.