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City of Highland Greenspot Road Bridge Project: How to Preserve History and Protect Communities

Greenspot Road has been home to a historic steel bridge for over a century. It’s a symbol of the City of Highland’s history in the citrus industry and an essential thruway connecting nearby communities. But the bridge, picturesque as it may be, was too narrow for the city’s traffic, and a restrictive vertical clearance and low weight limit spelled danger for 18-wheelers.

Moreover, the bridge is preceded by a dangerously sharp turn and was the frequent site of crashes, even earning it a Sufficiency Rating of 2 out of 100 in the 2004 Caltrans Bridge Inspection Report.

For such a vital artery in a community anticipating major growth in the coming decade, the situation was unacceptable. It was clear that City of Highland had to build an entirely new bridge to provide safe access for commuters, but what was to be done with the city’s historic landmark?

The answer: Combine the old with the new. Build a new bridge and retrofit the historic one, preserving history and protecting citizens.

Building a New Bridge to Solve Old Problems

The city enlisted us to provide construction management services to help construct the new bridge. It had to be wider—much wider—to accommodate legal loads and lots of traffic.

Considering the imminent residential and commercial development and the fact that the bridge is the only access point to the eastern part of the city, the highway was widened to a four-lane passage. This accommodates existing and future traffic, but not without taking environmental impacts into consideration. During construction, the contractor also provided mitigation to protect the nearby habitat of kangaroo rats and surrounding citrus orchards.

Five new wet and dry utilities were installed in the lost deck of the new bridge to connect to future utilities extension, and the roadway was realigned to connect to the existing Greenspot Road. This eliminated the sharp turn leading up to the old steel bridge and the undue traffic stops caused by turn and width restrictions.

New Greenspot Bridge with renovated historic bridge in background

Preserving a City Treasure

The old steel bridge may not have been able to handle the volume of vehicular traffic, but pedestrians, cyclists and equestrians were no problem! The city planners repurposed the bridge to keep pedestrians out of danger and minimize impact to the community.

But the steel bridge needed to be repainted by first removing the lead paint from the steel members. To avoid damage to the steel members from wind loading and contaminating the Santa Ana River bed, the bridge was completely contained during the paint removal process, with containment occurring one quadrant at a time. The project team also replaced the existing wood railings with plastic lumber and installed new AC pavement across the bridge for endurance and cost effectiveness.

Future plans have this Greenspot Bridge Trail connecting to the Santa Ana River Trail. That means the original bridge, initially constructed to serve the needs of the citrus industry, will live on as a useful historic landmark without the stress of traffic—and the resulting safety concerns.

Together, the old bridge and the new structure accommodate the entire community, preserving history while ensuring safety.


Carole Sanders, PE, QSD

Dubbed “The Queen of the SR-210” by the San Bernardino Sun, Carole specializes in the freeways and bridges that keep the Southland connected. With nearly three decades of experience, she’s a veteran of both the public and private sectors. She’s won numerous awards throughout her career, including Resident Engineer of the Year from Caltrans. She was also appointed to the Engineering Advisory Board at the University of California at Riverside, Bourn School of Engineering, to create and develop their School of Civil Engineering.

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