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.
14U – Unrelinquished Old Route 14
From San Fernando Road (now Newhall Ave) to Rainbow Glen Drive, along Sierra Highway, there is an unusual situation. Sierra Highway used to be a part of Route 14 until about 1972 when the Antelope Valley Freeway was completed through here. Normally, the bypassed section of roadway gets relinquished to the local jurisdiction. In this case, it wasn’t as the local agency, Los Angeles County Public Works doesn’t want the roadway because of maintenance issues. The roadway passes through some low hills between Placerita Canyon Road and Golden Valley Road which crumble rather readily in most rain storms. Flooding also occurs along this stretch which further exacerbates the problem. As a result, the roadway remains under Caltrans maintenance and is still signed as 14U.