We take it for granted, passing by at 65 miles per hour. The notch in the hill between San Luis Creek and Pismo Beach is not a natural feature, it been shaped and carved.
On Sept. 26, 1963 Telegram-Tribune staff writer Tom Harris wrote about the work:
New Route for 101
The face-lifting job freeway builders are doing on central San Luis Obispo County will provide some potent cure-alls for the highway ills plaguing motorists for several years.
The State Division of Highways project to convert about seven miles of expressway between the Santa Fe Bridge, south of San Luis Obispo, and the Price St. undercross, north of Pismo Beach will cost taxpayers approximately 3.2 million.
Another project, involving highway widening and alignment between 1.7 miles south of the Santa Fe bridge and the Los Osos road overpass, will cost an additional $1 million.
But, the returns indicate a special bargain for the motoring public.
The two projects will eliminate all cross traffic in an area that has long been a problem child for traffic safety officials in the county. They will straighten out curves that have been a graveyard for motorists.
Perennial crossing hazards will be abolished with four traffic interchanges—three of them undercrossings at the north end of Shell Beach, at Avila Beach road and a mile south of the present Santa Fe bridge. The fourth is an overpass at See Canyon road.
Of these, the underpass at Avila road is the most extravagant.
Before the general contractors E.C. Young of El Cajon, could even start laying the base of the huge earth and rock fill, they had to drill an intricate network of vertical drains to insure a safe and predictable settling process.
The drains are about 30-feet deep, 18-inches in circumference and filled with sand. There are 620 of them interlaced along the footwork of the fill.
Project engineer Dyler Campbell explained the need of the drains. “The tremendous weight of the 600,000 cubic yards of fill will force the water in the saturated clay beneath the fill to go somewhere,” said Campbell. “And rather than have it undermine the fill we put in the drains so the water will be forced up them and then carried off by a master drainage system.”
To further control the danger of unsafe settling, the fill can only be constructed a the controlled rate of three feet per week. Alternating layers of dirt, and both small and large rocks are rolled, packed and saturated by a fleet of bulldozers, earth movers and water trucks.
Work started on the big project July 1 and Campbell, a graduate of the University of Arizona, estimates the four-stage construction will be completed by May of 1965.