ITD begins work on the Lorenzo Bridge. Here’s an in-depth look at the project from start to finish.
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RIGBY — It takes years of planning for the Idaho Transportation Department to complete its summer road construction projects and one major item on the list this year is upgrading the Lorenzo Bridge on US Highway 20.
“The main purpose of what we do and what we spend most of our time doing is trying to do all these projects to maintain stuff (the roads) and keep it working,” said Curtis Calderwood, a staff engineer for ITD.
He said when the department builds roads, engineers design them with a 20-plus year lifespan. Bridges are constructed with a 50-plus year lifespan. However, he says without proper maintenance, the road surface will not last the full 20 or 50 years.
Calderwood said a road is like a thin piece of wire bent repeatedly, eventually breaking. With each vehicle, the road shifts and flexes a little, ultimately leading to cracking, rough and uneven surfaces.
Usually, ITD will perform some level of maintenance on the roads every five to 10 years, Calderwood said. Maintenance on the road could include sealing with a topcoat, removing or replacing the top surface of the road or, in the case of the Lorenzo Bridge project, a combination of resurfacing and updating safety features like guardrails.
“It’s all part of that maintenance and care of the road,” Calderwood said. “Once you throw the road down, you can’t just walk away.”
RELATED: Construction to begin on Lorenzo Bridge
The process of maintaining a road is years in the making. He said right now, ITD’s average project length is seven years, including planning, environmental studies, project engineering and ultimately physical completion of the project. In preparation for the estimated 95 working days on the Lorenzo Bridge project, ITD employees looked at how the project would impact the overall traffic flow of the highway. Project designers created detailed plans of where every sign, cone and marking would be placed while crews rehabilitate the bridge.
“Obviously we understand how important it is for people to be able to get from point A to point B and so whatever project we do, we rarely completely shut access down everywhere unless we have no choice and even then its for a very limited time,” Calderwood said. “We can’t work quite as fast on a project as we’d like because we have to make sure the traveling public can still get through.”
Construction crews have been using a hydro blaster to remove several inches of aging and cracked concrete in preparation to resurface with new road material. The hydro blaster leaves behind crumbled remains of the roadway, creating a possible environmental hazard.
ITD then uses a high powered vacuum truck to pick up remains of debris. Additionally, crews place barriers that prevent road waste from spilling into the Snake River. The waste is then transported off site to a proper waste disposal area.
One mission of ITD is the safety of motorists. Currently, guardrails on the Lorenzo Bridge sit around two feet high and are made of aluminum. While functional and decent, the current system on the bridge needs updating to comply with federal and state highway guidelines. Plans for the bridge show a steel tubular guard rail system that is about six inches higher than the current rails.
Work on the bridge will include work to the offloading and loading points, which engineers say take the brunt force of vehicles. With the need to repair rubber expansion joints and cracks, some crews will work underneath the bridge out of the eyes of the passing motorist.
“This project will greatly improve and extend the lifespan of the bridge,” said ITD Project Manager Alecia Johnson.
Idaho’s weather requires nearly all road projects to be worked on during summer months when temperatures allow for the placement of asphalt and concrete. Workers remind everyone to drive safe and be aware of construction zones this summer.
The ITD is working on the following 17 projects in eastern Idaho. A comprehensive overview of all projects is available on an ITD website.
- Interstate 15 Dubious to Spencer Road Reconstruction
- Interstate 15 Exit 113 Interchange
- Interstate 15 Rose Road Interchange
- Interstate 15 and Interstate 86 Junction to Fort Hall Boundary Road Reconstruction
- Interstate 15 Northgate Interchange
- Interstate 15 McCammon to Inkom Road Reconstruction
- Interstate 15 Virginia to Arimo Road Reconstruction
- US Highway 20 Targhee Pass
- US Highway 20 Ashton Hill to Dumpground Road Reconstruction
- US Highway 20 Lorenzo Bridge Repair
- US Highway 26 Aberdeen Canal Bridge Replacement
- US Highway 30 Georgetown Summit to Nounan Road Reconstruction
- State Highway 31 North Pine Creek Bridge Replacement
- State Highway 34 Bench Canal Bridge Replacement
- State Highway 38 Malad 50 south Street Reconstruction
- State Highway 39 Lateral A Bridge Replacement
- State Highway 39 Sheeptrail to Hoff Road Construction