Interstate 680 (I-680) is a north-south Interstate Highway in Northern California. It curves around the eastern cities of the San Francisco Bay Area from San Jose to Interstate 80 at Cordelia, bypassing cities along the eastern shore of San Francisco Bay such as Oakland and Richmond while serving others more inland such as Pleasanton and Concord.

I-680 is part of the State Scenic Highway System from SR 238 in Fremont north to SR 24 in Walnut Creek, and is eligible for said system from SR 238 south to the Alameda-Santa Clara County line.

Route description

The portion of this route from the Route 280/US101 junction to the Santa Clara/Alameda County line is named the Joseph P. Sinclair Freeway, after the District Engineer for District 4 Division of Highways (now Caltrans) from 1952 to 1964 pursuant to Assembly Concurrent Resolution 104, chapter 168 in 1967.

The portion of this route between Alcosta Boulevard and the intersection with I-580 is officially named the "Officer John Paul Monego Memorial Freeway." It was named after Dublin Police Officer John Paul Monego, who died on December 12, 1998, in the line of duty at the age of 33 years, while responding to a takeover robbery. Named by Senate Concurrent Resolution 60, enrolled August 18, 2000.

The portion of this route from Route 24 to Route 4 is historically part of "El Camino Sierra" (The Road to the Mountains).

The portion of this route from about the Livorna Road interchange in Walnut Creek/Alamo to the Alcosta Blvd. interchange in San Ramon appears to be named the "Donald D. Doyle Highway". While serving in the California Assembly from 1953 to 1958, Donald D. Doyle co-authored the Short-Doyle Mental Health Act and authored legislation creating the ferry boat transportation system between Benecia and Martinez. The signs indicating this were erected in 1998.

Of the above names, only the name Sinclair Freeway for its designated portion usually appears on maps, and the other portions on maps are always unnamed, referred to as simply I-680.

I-680 begins at a junction with I-280 and US 101 (Bayshore Freeway), and heads northeast and north-northwest through the northeast part of that city. After passing SR 237 in Milpitas and SR 262 in Fremont, I-680 abruptly turns northeast (where a connection to a SR 238 freeway was planned) and enters a hilly area. The highway crosses over Mission Pass, also known as the Sunol Grade, and descends into the Sunol Valley, where it meets SR 84 near Sunol. From Sunol, I-680 again heads north-northwesterly through valleys, including the San Ramon Valley, along the Calaveras Fault. Junctions along this portion include I-580 in Dublin and SR 24 in Walnut Creek. Beyond the latter interchange, a three-way directional junction with the SR 24 freeway west to Oakland, I-680 heads north into Pleasant Hill, where SR 242 splits and I-680 again heads northwesterly. After the junction with SR 4 in Martinez, the highway crosses the Carquinez Strait on the Benicia-Martinez Bridge, immediately meeting the east end of I-780 on the Benicia end. The remainder of I-680, from Benicia to I-80 at Cordelia, lies between a hilly area to the west and a marshy area (along the Suisun Bay and Cordelia Slough) to the east.

History

By the 1920s, a road ran south from Martinez through Walnut Creek, Dublin, Danville, and Sunol to Mission San Jose, where it met State Highway Route 5 (Mission Boulevard, signed over the years as US 48, US 101E, SR 9, and now SR 238). It was not yet paved south of Dublin, where it crossed Mission Pass between the Sunol Valley and the San Francisco Bay basin. The majority of this roadway was added to the state highway system in 1933 as portions of several routes: Route 108 from Mission San Jose to Sunol, Route 107 from Sunol to Walnut Creek, and Route 75 from Walnut Creek to Pleasant Hill.

At Martinez, the Martinez-Benicia Ferry took automobiles across the Carquinez Strait to Benicia, where Route 7, one of the original state highways from the 1910 bond issue, led north and northeast past Cordelia towards Sacramento and Oregon.Howe & Peters, Engineers' Report to California State Automobile Association Covering the Work of the California Highway Commission for the Period 1911-1920, pp. 11-16 The portion north from Benicia to Cordelia became part of Route 74 in 1935, when Route 7 was realigned to the more direct American Canyon route that is now I-80. None of the aforementioned roads were given state sign route numbers in 1934, when that system was laid out, but by 1937 they had been numbered Sign Route 21. This route began at the intersection of Warm Springs Boulevard and Brown Road in Warm Springs, where Route 5 and Route 69 (SR 17) split, follewed Route 5 along Mission Boulevard to Mission San Jose (this part later became an overlap with SR 9), and then continued to US 40 (Route 7) at Cordelia. The routing was very close to the present I-680, following such roads as Pleasanton Sunol Road, San Ramon Valley Boulevard, Danville Boulevard, and Pacheco Boulevard.

The portion of SR 21 between Pleasant Hill and Martinez was finally added to the state highway system in 1949, as a branch of Route 75. The ferry approach in Benicia became a spur of Route 74 in 1947, and in 1953 it was transferred to Route 75. The same law, effective immediately as an urgency measure, authorized the Department of Public Works to acquire the ferry system, then operated by the city of Martinez, which was planning to shut it down. Ownership was transferred just after midnight on October 6, 1953.

The Bureau of Public Roads approved urban routes of the Interstate Highway System on September 15, 1955, including a loop around the San Francisco Bay, soon numbered I-280 and I-680. The east half (I-680) began at the interchange of US 101 north of downtown San Jose and followed the Nimitz Freeway (SR 17/Route 69, now I-880) to the split at Warm Springs (the present location of SR 262), SR 21 to Benicia, and Route 74 (no sign route number) to I-80 in Vallejo. The first piece of I-680 freeway built, other than the pre-existing Nimitz Freeway, was in the late 1950s, along the SR 24 overlap between North Main Street in Walnut Creek and Monument Boulevard in Pleasant Hill. A southerly extension, bypassing downtown Walnut Creek to South Main Street, opened on March 22, 1960, connecting with the SR 24 freeway to Oakland. In the next decade, the freeway was completed from Vallejo south to SR 238 at Mission San Jose, and the roadway north from Benicia to Cordelia, which became the only remaining piece of SR 21, was also upgraded to freeway standards.H.M. Gousha Company, San Francisco, 1968

In the 1964 renumbering, the legislative designation was changed to Route 680. SR 17 was officially moved to former Route 5 between San Jose and Warm Springs, which had not had a signed designation since the Nimitz Freeway (then I-680) was constructed, : "Route 17 is from: (a) Route 1 near Santa Cruz to Route 101 near Story Road. (b) Route 101 near San Jose to Route 680 near Warm Springs. (c) Route 680 near Warm Springs to Route 580 in Oakland..." "Route 680 is from Route 280 in San Jose to Route 80 in Vallejo passing near Warm Springs, Mission San Jose, Scotts Corners and Sunol, and via Walnut Creek and Benicia." but this was instead marked as part of SR 238 (which replaced SR 9 north of Mission San Jose), and SR 17 remained signed along the Nimitz Freeway. This was very short-lived, as the Bureau of Public Roads approved a shift in the south end of I-680 in October 1964. The legislature changed the routes in 1965, swapping Routes 17 and 680 south of Warm Springs, and creating a new SR 262 on the short roadway at Warm Springs where they had overlap to switch sides. However, until I-680 was completed in the early-to-mid 1970s, it remained signed along the Nimitz Freeway, and the old road between San Jose and Warm Springs continued to be marked as SR 238. One more change was made to the routing of I-680: in July 1973, the remainder of SR 21, from Benicia to Cordelia, was added to the Interstate Highway System. This became the new alignment of I-680, and the old route to Vallejo became I-780. The corresponding changes were made by the state legislature in 1976.

Future

There is a proposal to add a high-occupancy toll (HOT) lane along I-680 between Alameda and Santa Clara counties. Under the plan, the existing southbound carpool lane along the 14-mile stretch between SR 84 and SR 237 would be modified to be the HOT lane. Solo drivers would then be required to use a FasTrak transponder. There are currently no plans to add northbound HOT lanes on I-680, however.

Exit list

Note: Except where prefixed with a letter, postmiles were measured in 1964, based on the alignment as it existed at that time, and do not necessarily reflect current mileage. The numbers reset at county lines; the start and end postmiles in each county are given in the county column.

County	Location	Postmile	#	Destinations	Notes
Santa Clara SCL M0.00-M9.94	San Jose	M0.00	1A		Continuation beyond US 101
		M0.00	1B		Southbound exit and northbound entrance
		M0.39	1A	King Road	Signed as exit 1C southbound
		M1.19	1B	Jackson Avenue	Northbound exit and southbound entrance
		M1.41	1C	Capitol Expressway (CR G21)	Signed as exit 1D southbound
		M1.74	2A	Alum Rock Avenue (SR 130)
		M2.38	2B	McKee Road
		M3.84	4	Berryessa Road
		M4.80	5A	Hostetter Road	Southbound exit is via exit 5
		M5.07	5B	Capitol Avenue	Signed as exit 5 southbound
		M6.17	6	Montague Expressway (CR G4), Landess Avenue
	Milpitas
		M7.65	8
		M8.50	9	Jacklin Road
Alameda ALA M0.00-R21.88	Fremont	M0.13	10	Scott Creek Road – Warm Springs District
		M2.38	12		Former SR 21 north
		M4.02	14	Auto Mall Parkway, Durham Road
		M5.37	15	Washington Boulevard – Irvington District
		R6.40	16		Former SR 21 south
		R7.48	18A	Vargas Road	Signed as exit 18 southbound
		R8.31	18B	Sheridan Road	Southbound exit is via exit 20
		R9.71	20	Andrade Road
		R11.04	21A		South end of SR 84 overlap; signed as exit 21 northbound; former SR 21 north
		R11.85	21B		North end of SR 84 overlap; southbound exit is via a U-turn at exit 21
		R12.44	22	Sunol	Southbound exit and northbound entrance; former SR 21
	Pleasanton	R15.26	25	Sunol Boulevard, Castlewood Drive – Pleasanton
		R16.75	26	Bernal Avenue – Pleasanton
		R19.30	29	Stoneridge Drive
		R20.06	30		Signed as exits 30A (east) and 30B (west)
	Dublin
		R20.39	30A	Dublin Boulevard	No northbound exit; former US 50
Contra Costa CC R0.00-25.46	San Ramon	R0.01	31	Alcosta Boulevard – Dublin
		R2.89	34	Bollinger Canyon Road
		R4.18	36	Crow Canyon Road – San Ramon
	Danville
		R6.76	38	Sycamore Valley Road
		R7.55	39	Diablo Road – Danville
		R8.18	40	El Cerro Boulevard
		R8.75	41	El Pintado Road	Northbound exit is via exit 40
	Alamo	R10.37	42	Stone Valley Road	Signed as exits 42A (east) and 42B (west)
		R11.28	43	Livorna Road
	Walnut Creek	R12.61	44	Rudgear Road	Southbound exit is via exit 45A
		13.08	45A	South Main Street – Walnut Creek	No northbound entrance; former SR 21
		13.93	45B	Olympic Boulevard
		14.38	46A		Signed as exit 46 southbound
		14.85	46B	Ygnacio Valley Road	Northbound exit and southbound entrance
		15.61	47	North Main Street – Walnut Creek	Former SR 21
		16.40	48	Treat Boulevard, Geary Road
	Pleasant Hill	R17.29	49A	Contra Costa Boulevard – Pleasant Hill	Northbound exit and southbound entrance; former SR 21
		R17.70	49B	Monument Boulevard, Gregory Lane	Signed as exit 49 southbound; former SR 24 east
	Concord, Pleasant Hill	R18.71	50		Northbound exit and southbound entrance
		19.04	51	Willow Pass Road, Taylor Boulevard
		19.86	52	Concord Avenue, Burnett Avenue – Pacheco, Concord
		21.19	53
		22.43	54	Pacheco Boulevard	Former SR 21
	Martinez	24.26	56	Marina Vista, Waterfront Boulevard – Martinez
		Benicia-Martinez Bridge over Carquinez Strait
Solano SOL L0.00-R13.13	Benicia
		0.68	58A		Signed as exit 58 southbound
		R1.00	58B	Bayshore Road	Northbound exit and southbound entrance
		R1.46	60	Industrial Park	Southbound exit and northbound entrance
		R2.82	61	Lake Herman Road	Former SR 21 south
		R5.02	63	Parish Road
		R7.32	65	Marshview Road
	Fairfield	R10.02	68	Gold Hill Road
		12.63	70	Green Valley Road – Cordelia	Northbound exit and southbound entrance
		13.13	71		Northbound exit and southbound entrance; signed as exits 71A (east) and 71B (west)

References

External links

• California Highways: Interstate 680