Hwy 14 starts off at I-5 with a rather impressive full interchange. Large and high flyover ramps connect all directions. This interchange has also had its share of problems. Originally under construction in 1971, it partially collapsed in the February 9, 1971 Sylmar / San Fernando Earthquake. Rebuilt by 1975, it collapsed again in the January 17, 1994 Reseda / Northridge Earthquake. Recently, a direct HOV connection from 14 to I-5 was added to the mix.
The Antelope Valley Freeway opened in segments. The first section from just west of Sand Canyon Road to Ward Road opened on August 23, 1963. The last segment from San Fernando Road to I-5 finally opened in 1975. In Canyon Country, a freeway interchange was planned for the SR-126 Freeway. Only a couple ramps were built as the whole freeway was cancelled a few years later. The number – 14 – was originally assigned to Artesia Blvd until 1963, when it was reassigned to the former routing of US 6.
The following photo is a milepost on Sierra Highway at Friendly Valley Parkway in Santa Clarita, CA. The mileage is not accurate to the road length. Here is the explanation : Mileposts in California are numbered by county. Mileage increases north and east. This milepost shows 30 miles to the end of the highway. SR-14 ends at I-5. Caltrans had planned on completing the highway from I-5 to the Pacific Coast Highway (SR-1) near Sunset Blvd. This is the reason for the anomaly.