RCTC and Caltrans are working on the $137 million reconstruction of the State Route 71/State Route 91 Interchange in Corona, expected to be completed by the end of 2025. The project aims to enhance safety, traffic flow, and access to different travel modes.
Caltrans photo
A roadway takes its basic shape.
By Irwin Rapoport
CEG CORRESPONDENT
The Riverside County Transportation Commission (RCTC) and California Department of Transportation (Caltrans) are reconstructing the State Route 71/State Route 91 Interchange in Corona, a vital corridor serving both commuter and commercial traffic.
At a cost of $137 million, the work is being performed by Skanska, with Falcon Engineering Services handling project construction management. Construction began in early 2023 and is anticipated to be completed before the year's end.
"The 71/91 Interchange serves as a gateway between Riverside, Orange and San Bernardino counties," said John Tarascio, RCTC's project manager and the senior capital projects manager.
The new non-tolled interchange is designed to improve safety, expand access to other modes of travel, reduce greenhouse gas emissions and enhance traffic flow.
The project will replace the existing single-lane loop connector between eastbound SR 91 and northbound SR 71 with a two-lane, direct connector ramp; build an eastbound SR 91 auxiliary lane to improve access to the new direct connector to northbound SR 71; and realign the eastbound SR 91 onramp from Green River Road to improve access to the 71/91 Interchange and southbound SR 71 to create space for the direct connector.
Caltrans approved the project's environmental documentation in June 2011, and RCTC completed the project's final design in June 2015. The RCTC received the final piece of funding in December 2020.
That funding includes contributions from the state's Solutions For Congested Corridors Program, the federal Better Utilizing Investments to Leverage Development program and the federal Infrastructure for Rebuilding America program.
The project, which was designed by Parsons Corp., has provided challenges throughout the process.
"The United States Army Corps of Engineers was a critical partner during the design phase, as there were unique right-of-way [issues] near the Santa Ana River channel," Tarascio said. "Another major challenge was spanning the SR 91 freeway, which has six general purpose lanes and two toll lanes in each direction. The falsework beams had to be spliced on site and spanned over 100 feet."
The project structures' lifespan is 50 years, and the pavement was designed for a 20-year lifespan. With the tall column heights and large bent caps, mass concrete was used, which required cooling tubes to be installed around the column during the curing process.
The construction plan works in stages to minimize motorist disruption through the heavily traveled corridor. Before work started, the corridor handled more than 100,000 vehicles per day.
The new configuration will have a similar capacity with the improved operational layout of the SR 91 to SR 71 connectors. The existing eastbound to northbound tight single-lane hook ramp will be replaced with a two-lane large radius flyover connector. The existing southbound SR 71 to eastbound SR 91 ramp will be reconfigured into two lanes. Both ramps will double in capacity.
So far, the project team has completed the following elements: the construction of retaining walls along southbound SR 71, the realignment of southbound SR 71 for the new connector and the construction of the eastbound SR 91 to northbound SR 71 connector.
The project team is finishing work on the eastbound SR 91 undercrossing and retaining wall along eastbound SR 91, as well as connecting the new ramps.
"The most challenging aspect of the work has been the foundations for the bridges," Skanska's team said. "The large diameter cast-in-hole piles were extremely difficult to construct because of unforeseen subsurface conditions and working room restrictions. The project is on schedule and the work is approximately 70 percent complete as of December 2024."
"Because the 2022-2023 winter season had a lot of rain and it raised the level of the groundwater table by 10 feet compared to what was shown in the original log of test borings, that created some challenges for the foundation work of the connector," according to Skanska.
The work to replace the single-lane loop connector between eastbound SR 91 and northbound SR71 with a two-lane, direct connector ramp is going well.
"Working beside and over the Santa Ana River and spanning eastbound and westbound SR 91 has been extremely challenging," Skanska said. "The new bridges are being built first around the interchange and then the freeway lanes will be connected to them. The one exception is on southbound SR 71 — the existing lanes had to be moved to the west to make room for the new eastbound SR 91/northbound SR 71 connector to come into the median of SR71."
The existing lanes will be connected to the new bridges when they are finished. The new lanes combine JPCP concrete pavement and HMA asphalt pavement.
Drainage infrastructure is being installed, too.
"There are 45 drainage systems that are either new systems or existing systems that are being modified," Skanska said. "All of the rainwater that lands on the new connector is captured using deck drains on the bridge and conveyed to the abutment or beginning of the bridge via a drainpipe system inside the bridge. New inlets and pipes are placed along the on ramp outside the limits of the bridge that convey the water away from the roadway."
Efforts are ongoing for the building of the eastbound SR 91 auxiliary lane to improve access to the new direct connector to northbound SR 71.
"To support this widening of eastbound SR 91," the Skanska team said, "multiple retaining walls have to be constructed to support the new roadway and embankment. This requires working along the existing right-of-way and close coordination with the existing commercial properties that are adjacent to the project."
These are concrete lanes that are 24-ft. wide with a 10-ft. outside shoulder. The length of the lanes transitioning into the new connector is approximately 1,400 ft.
Crews employ a variety of equipment including scrapers, excavators, motor graders, forklifts, cranes, HMA and JPCP paving machines, dozers, manlifts and drill rigs for this phase of work.
The realigning of the eastbound SR 91 on-ramp from Green River Road to improve access to the 71/91 Interchange and southbound SR 71 to create space for the new direct connector has its challenges.
"The new on-ramp requires building a new bridge over the BNSF and Metrolink tracks," Skanska said. "This bridge will have to be built first and then the approaches will be tied into it. On the east end of the bridge, a mechanically stabilized earth retaining wall will be constructed to support the embankment of the new on-ramp.
"The biggest challenge for the construction of the on ramp is working with the railroad. The new bridge goes over the tracks, and no work is allowed while trains are going through the project. This work has to be scheduled with the railroad and closely monitored."
Numerous Skanska and subcontractor employees are on location, with local and regional subcontractors helping.
Equipment on site includes cranes, excavators, dozers, loaders, scrapers, blades, backhoes, material handlers, HMA and JPCP paving machines, manlifts and drill rigs.
With so much equipment in use, Skanska mechanics are kept busy and complete repairs daily and ensuring that routine maintenance schedules are met.
Skanska buys and rents that equipment from numerous dealerships. CEG
(All photos courtesy of Caltrans.)
Irwin Rapoport
A journalist who started his career at a weekly community newspaper, Irwin Rapoport has written about construction and architecture for more than 15 years, as well as a variety of other subjects, such as recycling, environmental issues, business supply chains, property development, pulp and paper, agriculture, solar power and energy, and education. Getting the story right and illustrating the hard work and professionalism that goes into completing road, bridge, and building projects is important to him. A key element of his construction articles is to provide readers with an opportunity to see how general contractors and departments of transportation complete their projects and address challenges so that lessons learned can be shared with a wider audience.
Rapoport has a BA in History and a Minor in Political Science from Concordia University. His hobbies include hiking, birding, cycling, reading, going to concerts and plays, hanging out with friends and family, and architecture. He is keen to one day write an MA thesis on military and economic planning by the Great Powers prior to the start of the First World War.
Read more from Irwin Rapoport here.
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