Interstate 10/Santan Freeway System Interchange

Phoenix, Arizona

Olsson provided engineering services for part of this three-level system-to-system flyover interchange that connects existing Interstate 10 (I-10) to the Santan Freeway (Loop 202), including the plans, specifications, and estimates (PS&E) for a curved directional ramp, off-site drainage, and a pump station.

The eight-span structure is approximately 950 feet long and carries northbound I-10 traffic to westbound Loop 202. This cast-in-place, post-tensioned concrete box girder bridge was designed as a two-frame hinge system and has an out-to-out width of 31 feet, 2 inches. The abutments and piers are supported on spread footings.

The off-site drainage design we completed for this interchange included hydrologic analyses, storm drain design, and channel design. Results of the hydrologic analyses were used for design of the concrete lined channels, concrete box culverts, and a roller-compacted concrete basin.


Olsson also prepared the PS&E package for the storm drain pump station located in the southwest quadrant of this interchange. The four-level reinforced concrete structure consists of three underground levels extending 58 feet deep and a masonry building at ground level. The pump station was designed to accommodate three natural gas pumps with direct-drive engines, one submersible electrically operated pump, and a discharge box configured to include a splitter weir. Studies were performed to analyze the hydraulic operation of the station and optimize the pump and storage pipe design.