California State Route 242
|Defined by Streets and Highways Code § 542|
|Maintained by Caltrans|
|Length||3.398 mi (5.469 km)|
|South end||I-680 in Concord|
|North end||SR 4 in Concord|
State Route 242 (SR 242) is a three-mile (5 km) state highway in the U.S. state of California that links Interstate 680 north of Pleasant Hill to State Route 4 in Concord in Contra Costa County. Along with Interstate 580, State Route 24, Interstate 680 and State Route 4, it serves as the most direct route between the San Francisco Bay Area and the Sacramento–San Joaquin River Delta region.
In 2000, State Route 242 was widened to six through-traffic lanes for the entire route. Ramp metering is present at all onramps, and is used southbound in the morning and northbound in the evening. It was signed as part of State Route 24 until ca. 1987.
The route begins as a freeway at Interstate 680 in Concord. It then heads north, meeting Clayton Road, Concord Avenue, Grant Street, and Olivera Road before meeting its north end at State Route 4 just west of the former Concord Naval Weapons Station.
SR 242 is part of the California Freeway and Expressway System, but is not part of the National Highway System, a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration.
Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage. R reflects a realignment in the route since then, M indicates a second realignment, L refers an overlap due to a correction or change, and T indicates postmiles classified as temporary ( ). Segments that remain unconstructed or have been relinquished to local control may be omitted. The entire route is in Concord, Contra Costa County.
|R0.00||1A||I-680 south – Oakland, San Jose||Southbound exit and northbound entrance; south end of SR 242; I-680 north exit 50|
|R0.00||1B||Gregory Lane, Monument Boulevard||Southbound exit and northbound entrance|
|R0.87||1||Clayton Road – Concord||Northbound exit and southbound entrance|
|R1.47||1C||Concord Avenue||No northbound exit|
|R2.15||2||Grant Street, Solano Way|
|R2.79||3A||Olivera Road||Northbound exit and southbound entrance|
|R3.40||3||SR 4 / Port Chicago Highway – Stockton, Pittsburg, Richmond, Martinez||Northbound exit and southbound entrance; signed as exits 3B (west, Port Chicago Highway) and 3C (east); north end of SR 242; SR 4 exit 15A|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi|
- California Department of Transportation. "State Truck Route List". Sacramento: California Department of Transportation. Archived from the original (XLS file) on June 30, 2015. Retrieved June 30, 2015.
- Bay Area Metro Street Atlas (Map). Thomas Brothers. 2008.
- "Article 2 of Chapter 2 of Division 1". California Streets and Highways Code. Sacramento: California Office of Legislative Counsel. Retrieved February 6, 2019.
- Federal Highway Administration (March 25, 2015). National Highway System: San Francisco, CA (PDF) (Map). Scale not given. Washington, DC: Federal Highway Administration. Retrieved September 4, 2017.
- Natzke, Stefan; Neathery, Mike & Adderly, Kevin (June 20, 2012). "What is the National Highway System?". National Highway System. Washington, DC: Federal Highway Administration. Retrieved July 1, 2012.
- California Department of Transportation (July 2007). "Log of Bridges on State Highways". Sacramento: California Department of Transportation.
- California Department of Transportation, All Traffic Volumes on CSHS, 2005 and 2006
- California Department of Transportation, California Numbered Exit Uniform System, SR-242 Northbound and SR-242 Southbound, accessed February 2008
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