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Interstate 680 over the Benicia-Martinez Bridge and the legacy of California State Route 21

Recently I drove Interstate 680 over Carquinez Straight via the Benicia-Martinz Bridge.  The Benicia Martinez Bridge is significant as it was location of the last major highway ferry crossing in the San Francisco Bay Area on California State Route 21.


I-680 is a 71 mile Interstate Highway which begins at San Jose at the junction of US 101/I-280.  I-680 is aligned north through the historic corridor of CA 21 and crosses the Carquinez Straights to a penultimate terminus at I-80 near Cordelia.



Part 1; history of Interstate 680, California State Route 21 and the Benicia-Martinez Bridge

Before the Benicia-Martinez Bridge opened in 1962 traffic on CA 21 had to take a ferry crossing over Carquinez Straight.  Traffic on CA 21 northbound entered a ferry route located on Court Street north of downtown Martinez which crossed Carquinez Straight to 5th Street in Benicia.  The alignment of CA 21 between Martinez to Benicia on the ferry route can be seen in it's final form on the 1962 Division of Highways Map.

1962 Division of Highways Map 


The 1962 Benicia-Martinez Bridge is an approximately 1.7 mile long truss span design that now serves as the southbound lanes of I-680.  The 1962 Benicia-Martinez Bridge was built immediately west of 1930 Union Pacific Bridge which still is the longest rail bridge west of the Mississippi River in the United States.  The 1962 Benicia-Martinez Bridge greatly improved automotive traffic flow over Carquinez Straight and can be seen on the 1963 Division of Highways Map.

1963 Division of Highways Map


In my view it is impossible to have a legitimate historical blog/article/conversation about I-680 without including CA 21.  I-680 essentially is a modernization of the corridor occupied by CA 21.  CA 21 wasn't one of the original 1934 State Highways but was quickly added to the system by 1935.  CA 21 originally was routed from CA 17 (briefly CA 13) at Warm Springs Road northbound on the following alignment:

-  Mission Boulevard on Legislative Route Number 5 to Mission San Jose.
-  Mission Road on LRN 108 to Paloma Road. 
-  Paloma Road and Main Street in Sunol to Foothill Road.   I'm not sure if this was a spur of LRN 107 or LRN 108.
-  Foothill Road on LRN 107 to US 50 in Dublin at Dublin Boulevard.
-  Dublin Boulevard/US 50 to San Ramon Road.
-  San Ramon Boulevard on LRN 107 to Railroad Avenue in Danville.
-  Railroad Avenue to Danville Boulevard.
-  Danville Boulevard and Main Street on LRN 107 to CA 24 in Walnut Creek.
-  A multiplex of CA 24 on LRN 75 via Main Street and Contra Costa Boulevard to Pleasant Hill.  CA 24/LRN 75 split away from CA 21 in Pleasant Hill towards Concord.
-  Originally CA 21 was on County Maintained roadways between Pleasant Hill and Martinez; Contra Costa Boulevard and Pacheco Boulevard. (Note; it was likely that streets on the implied alignment of CA 21 in Martinez were likely never fully state maintained)
-  In Martinez CA 21 was aligned upon Jones Street and Pine Street to CA 4 which was originally on Escobar Street.
-  CA 21 multiplexed CA 4 on Escobar Street to Ferry Street.  CA 21 used Ferry Street to reach Court Street to the ferry over Carquinez Straight.
-  Upon crossing Carquinez Straight to 5th Street in Benicia the route of CA 21 picked up LRN 74.
-  In Benicia CA 21 followed 5th Street, L Street and 2nd Street to exit the city.
-  CA 21 used 2nd Street/LRN 74 and the general right-of-way of I-680 on Goodyear Road (I suspect the original road was razed by the Interstate) to US 40 in Cordelia.

CA 21 in it's original form can be seen on the 1938 Division of Highways Map.

1938 Division of Highways Map 


By 1940 State Highways were no longer signed on non-state controlled roads.  This led to a situation where CA 21 was likely not signed between Pleasant Hill and Martinez.

1940 Division of Highways Map 


By 1949 the legislative definition of LRN 75 had been amended to a include a spur from Pleasant Hill to Martinez.

CAhighways.org on LRN 75

State maintenance of CA 21 on Spur LRN 75 is shown between Pleasant Hill and Martinez by 1950.

1950 Division of Highways Map 


According to CAhighways.org the definition of Spur LRN 75 was changed in 1953 to include the Martinez-Benicia Ferry.  Apparently the City of Martinez at the time was looking at shuttering ferry service to Benicia.  The Martinez-Benicia Ferry has huge significance to the State Highway System as it was once part of US Route 40.  Given the significance the Martinez-Benicia Ferry it's history does carry merit to the topic of CA 21 and I-680.

The Martinez-Benicia Ferry began operation in 1847 and is the second oldest ferry in the San Francisco Bay Area.  The Martinez-Benicia Ferry shuttled traffic across the Carquinez Straights long before a bridge was present in the area.   The Martinez-Benicia Ferry was founded by Dr. Robert Semple and was taken over by Oliver Coffin (interesting last name) who built the Ferry Street Wharf in 1850.  By 1915 a steam ferry known as the City of Seattle was the first to carry automotive traffic across the Carquinez Straights.

Access to the Martinez-Benicia Ferry was by way of Legislative Route 14 and Legislative Route 7.  LRN 14 was originally defined as part of the 1909 First State Highway Bond Act according CAhighways.  LRN 14 was routed into Martinez via what is now Carquinez Scenic Drive east of Crockett.  Likewise LRN 7 between Tehama Junction and Benicia was also established as part of the 1909 First State Highway Bond Act according to CAhighways.  LRN 7 entered Benicia via 2nd Street.  LRN 14 and LRN 7 can be seen meeting at the Carquinez Straights at the Martinez-Benicia Ferry on the 1918 Division of Highways Map.


In late 1926 the US Route System was created.  The initial routing of US Route 40 was aligned over LRN 7 into Benicia, over the Martinez-Benicia Ferry and LRN 14 towards Oakland.  US 40 can be seen aligned over the Martinez-Benicia Ferry on the 1930 Automobile Club of Southern California.


The primary driver of US 40 being routed away from Benicia and Martinez was the completion of the original Carquinez Bridge in 1927.  The Carquinez Bridge originally carried the second alignment of the Lincoln Highway when it opened as a private toll bridge.  According to CAhighways a spur route of LRN 7 was adopted from LRN 14 in Crockett through the American Canyon Route in 1931.  This spur route of LRN 7 appears to have been completed some time in 1932.  US 40 was reported rerouted through Vallejo via the Carquinez Bridge and the American Canyon Route on the 8th Biannual Report by the Division of Highways in November 1932. 



By 1960 the planned route of CA 21 over the Benicia-Martinez Bridge appears on the Division of Highways Map.

1960 Division of Highways Map


By the 1964 State Highway Renumbering CA 21 was assigned as part of LRN 680.  I-680 was only signed over CA 21 from Walnut Creek over the Benicia-Martinez Bridge and the current route of I-780.

1964 Division of Highways Map 




By 1965 I-680 appears to have been co-signed with CA 21 between Mission San Jose and Sunol.

1965 Division of Highways Map


On the 1969 Division of Highways Map all of CA 21 south of the Benicia-Martinez Bridge is shown replaced by the completed I-680.  Note; I-680 used a temporary alignment co-signed on CA 17/Nimitz Freeway south of Warm Springs.

1969 Division of Highways Map 



The 1975 Caltrans Map shows I-680 completed south towards San Jose.


According to CAhighways.org the definition of the remaining segment CA 21 was changed in 1976 to become part of I-680 when I-780 was created.

CAhighways.org on CA 21

The modern form of I-680 and I-780 can be seen on the 1977 Caltrans Map.   CA 21 is shown to be completely removed as a designation.

1977 Caltrans Map 


In 2007 a new span of the Benicia-Martinez Bridge was built to carry northbound I-680 traffic. The northbound span is located directly east of the 1930 Rail Bridge and is a segmental structure.  Once the 2007 Benicia-Martinez Bridge opened the 1962 Bridge was converted to southbound I-680.   In total the 1962 and 2007 structures now carry 9 lanes of I-680.


Part 2; a drive on Interstate 680 from Interstate 580 north to Interstate 780

My approach to I-680 northbound was from I-580 westbound in Dublin of Alameda County.







I-680 north of I-580 is signed as 36 miles from Vallejo.  I-680 north enters San Ramon of Contra Costa at Exit 31 for Alcosta Boulevard.







I-680 north of Alcosta Boulevard is signed as a Scenic Corridor.


At Exit 34 I-680 north accesses Bollinger Canyon Road.




I-680 north Exit 36 accesses Crow Canyon Road.




I-680 north enters the City of Danville and next accesses Sycamore Valley Road at Exit 38.






I-680 north Exit 39 accesses Mount Diablo State Park via Diablo Road.




I-680 north Exit 40 accesses El Cerro Boulevard and El Pintado Road.



I-680 north in Alamo has an Exit for Stone Valley Road.




I-680 north next has another unnumbered Exit at Livorna Road.


I-680 north enters Walnut Creek and accesses Rudger Road at Exit 44.




At Exit 45A I-680 accesses Main Street and Olympic Boulevard at Exit 45B.  Exit 46A accesses CA 24 westbound.








I-680 north passes under CA 24 and accesses Exit 46B for Ygnacio Valley Road.




I-680 north Exit 47 accesses North Main Street.




I-680 north passes by a weigh station and accesses Treat Boulevard/Geary Road Exit 48.




I-680 north Exit 49A accesses Contra Costa Boulevard in Pleasant Hill.




I-680 north enters Antioch.  At Exit 49B I-680 north accesses Monument Boulevard whereas Exit 50 is the split for CA 242.





I-680 north passes under CA 242, enters Concord and accesses Willow Pass Road/Taylor Boulevard at Exit 51.





I-680 north Exit 52 accesses Concord Boulevard/Burnett Avenue.



At Exit 53 I-680 north meets the CA 4 freeway.




From CA 4 the toll plaza for the Benicia-Martinez Bridge is signed as only 2.5 miles to the north on I-680.  I-680 north in Martinez accesses Pacheco Boulevard.



Cash traffic is directed to the right hand lanes whereas Fasttrak users are directed to the left lanes.  Exit 56 for Marina Vista Avenue is the last exit before the toll booths.



Two axle vehicle tolls on the Benicia-Martinez Bridge are presently $6 dollars.



The Benicia-Martinez Bridge is presently signed as "Congressman George Miller Bridge."


The 2007 Benicia-Martinez Bridge is far from a scenic structure.  The 1930 rail bridge can be somewhat seen to the west but there isn't a single view of Carquinez Straight to be had from the actual roadway.  There is a vista point in the between the three bridges but I wasn't aware of it at the time.  My path after crossing the Benicia-Martinez Bridge had me turning west off of I-680 onto I-780.






As an interesting foot note it seems that the Martinez-Benicia Ferry and surface alignment of CA 21 north of Carquinez Straight was part of the original route of US 40/LRN 7.  The first Carquinez Bridge was completed in 1927 and it appears US 40 traffic was shifted to meet it possibly sometime between 1928 and 1930.  This can be seen by comparing the 1928 State Highway Map to the 1930 edition.

1928 State Highway Map 

1930 State Highway Map

It should also be noted that the Lincoln Highway moved from Altamont Pass and followed US 40 over the Carquinez Bridge when it opened in 1927. 

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