10/17/2011
Reed Hollinshead
ITD Communication
208-334-8881
reed.hollinshead@itd.idaho.gov
Transportation innovations help budget stretch
BOISE - In these tight economic times, the Idaho Transportation Department strives to find new and innovative ways to improve efficiency and stretch available funds. ITD's southwest Idaho office, located in Boise, has introduced a number of initiatives that help the department achieve the most with its available funding.
The efficiencies and innovations were in the areas of traffic control, extending pavement life and maintenance measures.
D-Tec Traffic Detection
In May 2011, ITD experimented with a new multi-sensor traffic-detection system at the Northside Boulevard intersection that serves the westbound on-ramp traffic heading onto Interstate 84 in Nampa.
"Traditional loops in the pavement required too-frequent replacement, and heavy trucks going to and from the nearby sugar beet processing plant were prematurely deteriorating the roadway surface," said Traffic Manager, Kevin Sablan. "Loops would not last long enough, and using signals based on video detection also was problematic because of 'fog,' created in part by the factory. The D-Tec system claims not to be affected by fog and ambient street lighting."
If traffic engineers are not satisfied with the performance of the new D-Tec equipment, the contract allows replacing it with a video-detection system. The eastbound ramp at that location is based on video-detection, so the interchange will serve as a “controlled” lab experiment.
The cost benefit for the system comes from its longevity, performance in fog and lower maintenance since lenses on a video-detection system require frequent cleaning.
Idaho 52 SAFLEA
In August 2010, a new treatment method was used on a section of Idaho 52 near Emmett in need of surface repair. A process called Stress-Absorbing Fiberglass Layer of Emulsified Asphalt (SAFLEA) was used to allow crews to apply a seal-coat finish to the surface layer, extending highway life.
The SAFLEA treatment strengthens and reinforces a traditional sealcoat by sandwiching two-inch long chopped fiberglass strands between two layers of asphalt emulsion.
"After the emulsion and strands are applied, chip-seal aggregate is placed and rolled as normal," said Project Engineer, Jeff Morf. "The reinforced surface slows cracking and resists snowplow damage. Although the technology is somewhat new to Idaho and surrounding states, it has been used successfully in Europe the past two decades."
Using the SAFLEA process on the 13.2-mile project cost only 20 percent more than a standard seal coat, while extending the life of the roadway another 5-10 years.
U.S. 95 Culvert Replacement
A little less than a year ago, ITD’s maintenance force faced an expensive repair to a large, plugged culvert under a section of U.S. 95 that needed to be replaced. A contractor estimated the repairs at $50,000, a higher amount than expected and difficult to justify in an environment of tight budgets.
Instead, ITD decided to look internally for a solution. A log jam was blocking the inlet to the culvert where the East Fork of the Weiser River crossed under the highway about nine miles north of Council. If enough debris collected and stopped the water flow, it would create a dam. In addition, the earth fill for the road was not designed to hold back the amount of water building up, and would have failed had the water pressure become too great. This would have washed out the roadway and possibly even destroyed the dozen or more homes downstream from the culvert.
There also was urgency. It was the end of October 2010, and on Nov. 17, the East Fork of the Weiser River would be declared critical Bull Trout habitat. ITD had to complete the repairs before mid-November.
Crews also could not take the chance that spring floods would bring more debris.
There were several smaller log accumulations still sitting on the bank upstream that threatened to (and ultimately did) wash down with the spring runoff. The crew was racing the clock for another reason - because of the severe slope of the access road, any moisture would have made it difficult to get equipment and trucks to the site, and rain was predicted for Nov. 7.
ITD's Special Crew and New Meadows maintenance finished repairs Nov. 6. It started raining that evening.
“This was a very extensive project with little time to complete it. We completed it in six days, working daylight to dark straight through to completion,” said Special Crew foreman Dave Dansereau.
The department spent $6,500 to rent an excavator and $11,000 on materials and wages, for a total outlay of $17,500 – far below the initial $50,000 estimate and an example of making the dollar stretch in tight times.