Award Winner

ASCE Project of the Year – Community Improvement Project 2015

Construction Management Project Award – Construction Management Assoc. 2015

SR 99 / SR 104 / Twin Cities Road Roundabouts

Galt, CA

This interchange was more than 50 years old and in need of replacement, but reconstruction was still decades away. The estimated $60 million price tag for traditional signalized ramp terminals also made any improvement to the interchange cost prohibitive. Surface street intersections on SR 104/Twin Cities Road at the frontage roads and the existing two-lane overcrossing structure of SR 99 – all within the state right of way – were at their capacity and were limiting development in the city. These intersections, controlled by traffic signals, were operating with unacceptable queues in danger of backing out onto the freeway.

The MTJ/Omni-Means team developed a cost-effective and timely solution that included two closely spaced roundabouts and a new freeway on-ramp to replace the existing congested signalized intersection. This solution preserves the existing overcrossing and eliminates existing congestion while providing increased capacity of the interchange to accommodate future growth.

The construction cost of the completed project is estimated to be approximately $6 million – one-tenth the estimated cost of the interchange replacement utilizing traditional widening with signalized ramp terminals.

 

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