Interstate 680 California
One of the busiest freeways in the East Bay, Interstate 680 connects the communities of Benicia, Concord, Walnut Creek, Danville, Sunol and San Jose. The section between Interstate 580 and the Benicia Bridge underwent extensive reconstruction through the late 1990s, resulting in an eight to ten-lane freeway with carpool lanes.
Additionally Interstate 680 through the Sunol Grade was improved in 2001-2003. As part of the eight lane expansion, two bridges that were constructed in part for the planned interchange with SR 238 (Hayward Bypass/Mission Freeway) were removed.
The Interstate 680 corridor was previously part of California 21. Construction of the freeway gradually overtook the state route between San Jose and Fairfield in the 1960s and 1970s.
Prior to 1976, the northern most extent of Interstate 680 turned west from Benicia to I-80 at Vallejo. This changed with both the establishment of Interstate 780 along the former east-west leg to Vallejo and the extension of I-680 north over what was the remaining section of California 21 between Benicia and I-80 at Coredlia.
The 1.2-mile long, deck-truss Benicia-Martinez Bridge over the Sacramento-San Joaquin River Delta was augmented with a parallel bridge. Started in 2001, this project involved the replacement of approaches for northbound traffic along with a new bridge structure located east of the original span. Following completion of the second span on August 25, 2007, the existing 1962 bridge was retrofitted to meet state seismic standards and restriped to carry southbound traffic. With the completion of the $1.2 billion project, the regular congestion that occurred as part of the reduced lanes, toll plazas, and the adjacent interchange with I-780 diminished.1
North End – Fairfield, CA
South End – San Jose, CA
Mileage – 70.52
Cities – San Jose, Milpitas, Fremont, Walnut Creek, Concord
Source: December 31, 2018 Interstate Route Log and Finders List
I-680 Annual Average Daily Traffic (AADT)
Source: Caltrans 2017 Traffic Volumes : Route 505-980
California 21 was replaced by California 17 and Interstate 680 between San Jose and Cordelia. The last segment was transferred to I-680 in 1976.
Interstate 680 in San Jose was completed in 1974, two years after the opening of Interstate 280. Note that I-680 was temporarily signed along California 17 to make the connection between San Jose and Fremont.
North End – Fairfield, California
Exits 71A-B separate from I-680 north for I-80 & SR 12. Interstate 80 & SR 12 east divide at Fairfield with SR 12 continuing to Lodi and I-80 angling northeast to Sacramento. Interstate 80 and SR 12 partition just west of I-680. The state route navigates through Jameson Canyon toward Napa, Sonoma, and Santa Rosa. Interstate 80 turns southwest through American Canyon toward Vallejo. 06/21/15
Exit 41 departs I-80 & SR 12 west for areas of southwest Fairfield at Green Valley a half mile ahead of Interstate 680. 07/11/18
South End – San Jose, California
Southbound Interstate 280 at the systems interchange with U.S. 101 and transition to I-680 north. 11/25/07