HIGHWAY 138: Realignment Project Eliminating Switchbacks Continues

The existing non-standard horizontal and vertical curves — known as switchbacks — will be eliminated when Skanska USA completes the Highway 138 East Realignment Project. A temporary bypass will open to motorists on January 9. (Photo by Caltrans)

By Michael P. Neufeld

Hesperia, CA – Skanska USA continues work on the $23 million Highway 138 East Alignment Project just east of Interstate 15 to Summit Post Office Road, according to a media advisory issued by Caltrans.

A great deal of the existing route has no paved shoulders and narrow or non-existent earth shoulders. (Photo by Caltrans)

As the project in Summit Valley progresses, the switchbacks and steep grades between Silverwood Lake and I-15 will disappear.

The Caltrans release explains the project realigns the roadway, constructs outside shoulders and three wildlife crossings near Hesperia from 1.9 miles east of I-15 to 0.1 mile west of Summit Post Office Road.

Highway 138 will remain a two-lane road with one lane in each direction although the “new” realignment will be a mile shorter than the existing route.


Starting on Monday, January 9, Highway 138 motorists will be driving on a new temporary pavement in the area of Hog Ranch Creek Bridge. The temporary roadway is just over two miles east of I-15.

Caltrans reports that the new traffic pattern will be in place until the completion of the project.

Flaggers and advanced warning signs will be in place to alert the traveling public of the new traffic configuration.



Some existing curves and grades on Highway 138 are as steep as 15 percent. (Photo by Caltrans)

The “new” roadway on Highway 138 will have full 12-foot lanes in each direction, plus full shoulders of 8 to 10-feet each.

To construct the  “new” roadway, Skanska will be required to excavate about 777,000 cubic yards of dirt, traverse seven (7) tributaries of Crowder Creek, which is a tributary to Lytle Creek and ultimately the Santa Ana River.

The contractor will build three (3) new bridges requiring the excavation of 1,160 cubic yards of stream bank and placement of 2,657 cubic yards of rock slope protection within the streambeds.

The Arroyo Toad (Contributed Photo)

A total of 11 new culverts will be installed and 15 existing culverts will be removed.

The project alignment is to be located outside the designated critical habitat for the federally-listed endangered Arroyo Toad (Anaxyrus Californicus).

Construction is expected to be completed by summer 2018, although Skanska has indicated it hopes to complete the project ahead of schedule.