California’s State Route 91 (SR91)

Project Stats


Our highways and road systems connect Americans from coast to coast. They serve as reliable, efficient modes of transportation for vacationers, traveling business people, and commercial goods.

California’s State Route 91 (SR91) is a major east-west thoroughfare stretching 59 miles from Gardena to Riverside. As a busy freeway that serves several regions of the Greater Los Angeles urban area, it had become prone to severe congestion, requiring innovative thinking to help keep traffic flowing as smoothly, safely, and efficiently as possible.

The Project

The SR91 corridor needed increased traffic capacity to accommodate the over 280,000 vehicles that used it daily. The Riverside County Transportation Commission allocated $632M for innovative solutions that would mitigate congestion both today and in step with future growth expectations.

The commission brought Atkinson/Walsh, a joint venture, on board to help develop forward-thinking solutions that solved the commission’s need. Their strategy included the following:

  • Extending the existing Orange County Transportation Authority (OCTA) SR 91 Express Lanes eight miles east to I-15 in Corona, CA
  • Widening the existing interstate from five to eight lanes in each direction
  • Expanding the single HOV lane to two express toll lanes, adding one general purpose lane, and adding an auxiliary lane to manage on/off-ramp traffic
  • Adding a toll express lane connecting eastbound SR 91 to southbound I-15
  • Road improvements to I-15 and at the SR91/I-15 interchange 

Included in the scope of the work were 32 bridges and 100 retaining walls, all of which demanded quality precision detailing, construction, and installation. To help facilitate the building of these new structures and bring the project to its intended destination, Atkinson/Walsh brought MSL to the table.

MSL’s Approach

Our team of detailers, engineers, and installers understand that the quality and durability of any project matters when the rubber meets the road. We helped meet our client’s expectations by employing a fully collaborative process throughout the scheduling, detailing, logistics, and installation phases.

The ambitious work plan required the experience and talent of our entire team and an open communication approach that ensured that all stakeholders were on the same path. Our client was always in the driver’s seat during this complex project’s lifecycle. Our detailers, fabricators, engineers, and installers were always available to answer their questions and provide knowledgeable feedback when needed.

The Results

MSL fulfilled all of our requirements on time and under the original budget, installing more than 5,000 tons of concrete and steel over the course of the project. The refreshed highway opened on March 20, 2017, to much fanfare and positive reviews from our client and the public.

Our team is committed to working on projects that improve the lives of our fellow Americans by keeping our nation’s road systems safe and efficient with solutions built to last for generations.


Experience the MSL difference for yourself by booking a no-obligation pre-construction meeting today. Simply fill out the below form to get started!

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