The Idaho Transportation Department is working to improve 5 of the Lemhi River Bridges on SH-28.
Part of a 2 year bridge project, ITD has began construction on the remaining 5 bridges left to be replaced out of a total of 17 bridges that began in 2018. The remaining 5 Lemhi River Bridges are located on SH-28 from milepost 106.5 to 115.5 and will each entail a full bridge replacement. Four of the five bridges have begun construction starting this March and the last bridge at milepost 115.5 will start this July. Each of these 5 bridges will be completed late this fall.
For the first time at ITD, a unique district collaboration within Districts 4, 5 & 6 were able to come together and identify 17 bridges that were in dire need of replacement. In discovery of the 17 bridge replacements, the team united to create 1 project in turn saving over $3 million by which this savings. By doing this, creating 1 project vs. 17 projects, it allowed ITD to save money, increase mobility and economic opportunity.
In reaching their prospective life span of 50 years old, each of those 17 bridges were in need to be replaced. Each bridge will be brought up to current design standards; being wider to accommodate wider shoulders or future widenings, and in most cases longer, to better accommodate the ever changing waterways. As a result of the future shoulder widenings we will be minimizing the amount of guardrail needed.
By constructing 17 bridges under one contract & in multiple areas, long term impacts to the traveling public are minimized. The project team minimized the impacts to the traveling public by:
Successful in acquiring the data collection and concept designs for these 17 bridges, we were able to do this at a fraction of the cost versus if it had been all done individually. When estimated and budgeted, ITD had budgeted $27 million for this unique project. Once our budget was set, the bid opened at $24 million then saving ITD $3 million. This incredible savings is associated with grouping projects across district lines and working together. We were able to have only 1 point of contact on this project within the 3 districts. In the past there would be 1 point of contact per project in turn potentially equaling 17 projects/17 points of contact for these individual bridges. Not only is ITD saving at least $3 million, we are also saving a tremendous amount of time.
The project team decided in re-building these bridges, we would utilize ABC construction (accelerated bridge construction). We would be using pre-cast products such as abutments and the bridge deck. To lock and secure the pre-cast sections together, the team chose to use ultra-high strength concrete.
An astonishing 1 year is all it took the team from selecting which bridges to be reconstructed, collect data for 17 sites, to having a Design-Build Firm under contract. Traditionally, by treating each bridge as individual projects it would have taken numerous years and a multitude of resources in order to complete. By working collaboratively within multiple districts and contractors, ITD is acquiring high quality work and products along with huge savings in time and money.
With many of these bridges currently under construction, all of these 17 bridges will be completed by fall of 2019. Had we used our traditional process, it could have taken over 20 years to complete all 17 bridges. By changing the way ITD does business we have changed the impact we have on our mission…Your Safety, Your Mobility, Your Economic Opportunity.