SR 237/I-880 Interchange, Santa Clara County
The Project
This major transportation improvement project replaced the SR 237/I-880 full cloverleaf type interchange with a direct freeway-to-freeway connector from eastbound SR 237 to northbound I-880; a direct freeway-to-freeway connector from southbound I-880 to westbound SR 237; and grade separated the freeway traffic from the eastbound and westbound local street traffic on Calaveras Boulevard. The overall project cost was funded from HEII STIP, and from the City of Milpitas and Santa Clara County ½ cent sales tax program.
MTCo led the planning, final design and PS&E for the project improvements which included nine bridges; 12 retaining walls in height of up to 28 feet; relocation of two 30-inch and 36-inch PG&E gas mains, 14-inch City water main, eight-inch City sewer system, PG&E overhead lines and SBC major communication system; relocation of the local access road and construction of a new local access bridge over Coyote Creek; Coyote Creek improvements; and design coordination with the Alameda County I-880 improvement projects.
The Challenges
Design Challenge: In order to bring the overall project cost within budget, MTCo evaluated 15 major PDR (pre-design report/value engineering) alternatives which included design options for undercrossings in lieu of overcrossings, flipping profiles of two crossing ramps, widening out median to accommodate HOV direct connector, and separating local roadway networks from state facilities.
Implementation Challenge: The design originally commenced as part of the last project under the original ½ cent sales tax program, led by Santa Clara County Traffic Authority. After one year in the design process, Traffic Authority issued a stop notice due to shortages of measure funds. The project was on hold for three years.
The Results
When funding was secured, City of Milpitas became the lead agency to complete the design phase. MTCo quickly remobilized the design team and completed the final PS&E in nine months. MTCo delivered the final PS&E in 21 months, three months ahead of the planned schedule.
In addition, MTCo PDR process resulted in a total cost savings of over $4.5 million as well as implementing the first Santa Clara County HOV to HOV direct connector.