Interstate 238 (I-238) is a short auxiliary route of the Interstate Highway System in the San Francisco Bay Area, California, United States. Part of State Route 238 until 1983, and still considered the same route (part of Route 238) by the California Department of Transportation (Caltrans), it connects Interstate 580 in Castro Valley (where SR 238 continues south) with Interstate 880 in San Leandro. Despite running in an east-west direction, it is signed north-south, as the rest of Route 238 is more north-south than east-west.

The number does not follow established rules for numbering Interstates, as there is no Interstate 38. Of the nine possible numbers ending in 80 (as it connects two auxiliary routes of Interstate 80), two - 180 and 480 - were in use by State Routes (the latter an Interstate until 1968), and the seven others were used by other Interstates. (I-880 was designated at the same time as I-238; it too could only be an auxiliary route of I-80.)

This route is part of the California Freeway and Expressway System.

Route description

Although the I-238 goes in an east-west direction from Castro Valley to San Leandro, Caltrans officially signs it as a north-south freeway since the rest of State Route 238 is more north-south. The south (or east) terminus of I-238 is at its interchange with Interstate 580 and SR 238 in Castro Valley. From there, it enters into the southern portion of the census-designated place of Ashland, running parallel to its border with Cherryland. Then after entering San Leandro, I-238 terminates at Interstate 880.

History

The section of road that is now I-238 had no signed number before the 1964 renumbering; it was pre-1964 Legislative Route 228 (along with an unbuilt extension west to unbuilt State Route 61, which is still included in the Route 238 definition).

The segment from what is now I-580 to I-880 was built as a freeway in 1956. The rest of SR 238 south to Interstate 680 in Fremont was also planned to be upgraded to a freeway (parallel to present I-880), but after it was unsuccessfully submitted to the Interstate Highway System in October 1968, and after several lawsuits, it never got off the ground.

When present Interstate 880 was added to the Interstate Highway System as a renumbering of part of State Route 17, the short piece of SR 238 connecting I-880 to I-580 was also added; both were non-chargeable routes (not eligible for Interstate Completion funds). Both numbers — I-238 and I-880 - were approved by the American Association of State Highway and Transportation Officials (AASHTO) on July 7, 1983. The interchange with I-580 and I-880 were rebuilt from 1988 to 1994, in part to add missing ramps between I-238 and I-880 towards the south. Prior to the completion of the ramps, access was provided by Hesperian Boulevard.

As the American Association of State Highway and Transportation Officials said on July 7, 1983 when approving the designation,Caltrans responded on July 27, 1983:

With the deletion of State Route 480 in 1991, the "480" designation is once again available.

Future

The entire length of I-238 is being reconstructed, including a reconfigured interchange with I-880, and an added travel lane in each direction. The existing pavement is being removed to allow for the roadbed to be rebuilt, then new pavement will be laid. Additionally, almost all of the bridges and overpasses are being replaced with new ones meeting current earthquake resistance standards.

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 entire route is in Alameda County.

Location	Postmile	#	Destinations	Notes
Castro Valley	R14.47	14		Southbound exit and northbound entrance
	R14.47			Southbound exit and northbound entrance
Ashland	14.95	15
San Leandro	16.28	16B	Hesperian Boulevard – San Lorenzo	Northbound exit and southbound entrance
	16.70	16A	, San Mateo Bridge	Northbound exit and southbound entrance
	16.70	17A	Washington Avenue	Northbound exit and southbound entrance
	16.70	17B		Northbound exit and southbound entrance

References

External links

• Indigestion 238: A history of the route and a full explanation of its numbering
• Kurumi - I-238 California