Background

The SR-189 Design-Build (DB) project connects community and commerce while improving safety and mobility in Nogales, Arizona. A critical pathway for international trade with Mexico, this highway facilitates passage of 6 million pounds of produce each year. On any given workday, one out of every five vehicles on SR-189 is a freight truck. This high volume of truck traffic caused major delays at the Mariposa Port of Entry and along 189 as trucks move through the interchange at I-19 to advance their shipments north, calling for a redesign.

Project Details

Beginning at the U.S./Mexico International Border at the Mariposa Port of Entry and extending to the intersection of Grand Avenue, this project focused on widening SR-189 and adding flyover ramps to better facilitate traffic flow in this busy international shipping corridor.

Horrocks' DB team used a structure-focused construction phasing plan to minimize public inconvenience, as it was critical that the port operate as normally as possible during construction. Teams worked to minimize traffic shifts while maximizing capacity to help support shipping vehicles throughout construction. Due to right-of-way (ROW) constraints, flyover ramps were designed for traffic to enter and exit to a median then connect to SR-189 and Frank Reed Road beneath those ramps. A split left-turn lane wrapping around a critical ramp pier was also added, allowing the bridge to span continuously until reaching the directional split over the Mariposa Wash Bridge. This unique innovation spared significant costs by nullifying many ROW acquisitions along SR-189.

Outcomes

Widening improvements to SR-189 and the addition of flyover ramp structures at the interchange with I-19 have greatly improved safety and traffic flow for commercial trucks and the driving public in the Nogales community. This highway is critical for international trade with Mexico, and improving its function will benefit North American trade and tourism while also fostering a safer traveling environment for drivers and residents in nearby communities on both sides of the border.