From its I-5 terminus, the I-210 freeway did extend only to MacLay Street (then part of CA 118) until 1981, when it was extended to the Foothill Blvd./Osborne St. exit (the access road into Little Tujunga Canyon). From the east, 210 had been completed through the CA 2 interchange to Ocean View Ave. in La Crescenta by 1976, to La Tuna Canyon by 1979, and finally to Sunland Blvd. by 1981. The section from about 2 miles east of La Tuna west to Sunland followed the ridge line of the Verdugo mountains, complete with several substantial gradients in each direction. The final section, from Sunland Blvd. to Osborne St. was completed in 1983; this crossed the Big Tujunga Wash floodplain upstream from Hansen Dam; Caltrans bridge engineers had extreme difficulties constructing the crossing because of the depth of usable bedrock, buried under layers of sand and debris washed out of the Big Tujunga canyon. This situation was virtually identical to that found in the San Bernardino area crossings of the Santa Ana River; the eventual solution also used buried caissons, tamped down until they wouldn't go any further, with bridge columns rising up from there. From 1981 to 1983 through westbound traffic exited at Sunland Blvd., went east to Wheatland, a local arterial, then north a couple of blocks to Foothill Blvd. (old CA 118), then northwest across the existing Big Tujunga bridges before turning west to the already-completed Osborne interchange, where it resumed freeway travel. It was signed "TO I-210" in both directions.
That area was the location site for several film & TV productions, most notably the film "Chinatown"; the old CA 118 bridge over the Big Tujunga Wash was where the P.I. Jake, the character played by Jack Nicholson, was searching for traces of water releases from upstream. Later (1977-81) the uncompleted I-210 between MacLay and Osborne, including the CA 118 interchange, was the go-to freeway filming site for the TV series "CHiPs" (every time I've driven along that section I keep hearing that damn disco music they used as a background score!).