Innovation in inspection of overhead sign structures
saves $320K annually

There are nearly 2,000 overhead sign structures on the state highway system, and more than a quarter of them are inspected each year. Finding even a slight savings in the per-unit cost can result in a significant overall savings, and that’s just what the ITD Bridge Asset Management team has done.

Bridge inspection is done at the element level, meaning that each structural element is assigned a condition rating, which is used to make maintenance or replacement decisions. In order to provide the same level of inspection accuracy and consistency across the board, an element-level, overhead structures inspection program was implemented in 2016.

The new element level overhead structure inspection program utilized nationally recognized inspections experts Collins Engineers. With overhead structure inspection data now collected at element level, ITD modified aspects of their bridge inspection software to accommodate and manage data from the nation’s only element-level inspection of overhead structures

Pictured at right: An inspector conducts a review using high-powered binoculars rather than impacting traffic flow.
The result goes beyond monetary savings and efficiency, to enhancing safety for travelers on Idaho’s 12,000-mile state highway system.

Additionally, ITD’s robust overhead structure inspection program prolongs the usable life of the signs. The replacement cost can exceed $200,000 if an overhead structure fails.

“In addition to the safety improvements on the structures themselves, we were able to employ some innovative inspection and traffic-control techniques such as the utilization of high-powered binoculars and climbing structures rather than closing lanes,” Legler explained.

 “That not only made it safer for our workers and less obtrusive to the traveling public, but it also brought the inspection costs down significantly,“ he added.

“In the 2005 contract, we paid an average of around $1,200 per structure,” said Technical Engineer Service Lead 3 (TESL) Jake Legler. “In our most recent contract (April 2017), we are paying an average of $400 per structure. We are inspecting an average of 500 structures per year. We estimate a savings of nearly $320,000 per year.“  

(Note: the $400,000 savings this year is due to many cheaper-to-inspect signal arms; the $320,000 estimated annual savings is based on a typical regional average.)

Legler said the inspection cost reduction is due to several reasons:

Traffic Control – In the earlier contract, traffic control shadowed inspectors everywhere they went. Now, inspectors climb structures from the shoulder and make use of high-powered binoculars for signal arms and high mast lighting, rarely using traffic control.

Reduced risk to contractor – The contract is cost + fixed fee, which reduces the risk put on the contractor.

Increased Contractor flexibility  - ITD allows the contractor to schedule the inspections within the calendar year to efficiently fit their manpower and equipment.


Published 07-28-17