Every spring, when the road surfaces begin to thaw, heavy loads can inflict serious damage to some of our highways. D-3 Maintenance is taking the lead in investigating methods to avoid this damage in frost-susceptible roads.

In addition to D-3 involvement, the Spring Breakup Team is composed of ITD representatives from D-1, D-2, D-5 and D-6. They are incorporating research already done in Washington State and most notably, Minnesota, although geographic inconsistencies prevent ITD from incorporating Minnesota’s study on a wholesale basis.

The difference in elevation between the highest and lowest roadway surfaces in Minnesota is about 1,700 feet, while that difference in Idaho is about 8,000 feet. These elevation differences and other discrepancies mean that Minnesota’s data does not always corealte smoothly with the Idaho study.

Research from the Federal Highway Administration and the Minnesota Department of Transportation has provided the following intriguing nuggets about roads susceptible to frost damage:

1. The load-bearing capacity of a road can be reduced by as much as 50 percent during the spring, when thawing and drying of the road base and foundation occurs.
2. Frost-susceptible road structures are far more "tender" during the beginning of the thawing and drying process than later in the spring, meaning they are liable to sustain more damage early.
3. Speed reductions generally do not help preserve the road structure during spring breakup.

“We’ve found that the vast majority of the damage that a road sustains occurs within the first week of thaw when the heavier loads start rolling,” said Tom Points, D-3 Operations Manager. “The data also indicates that we could add to the life expectancy of a highway by incorporating breakup countermeasures. Making our dollars stretch further is the name of the game.”

Idaho's optimism comes from Minnesota, where they expect to add 10 percent to the life expectancy of their roads by the effective use of spring breakupweight limits, said Tom Haynes, who is organizing the spring breakup study for D-3. There could be significant savings for Idaho, too.

Haynes figures we are still a few years from having a systematic approach to the problem. However with the assistance of numerous ITD employees, installation of recording instruments has begun that will aid in determining whether the ‘Minnesota Method’ will work for Idaho.

"Given that we are the Highway Department, and this is one way to save our highways and potentially money for maintenance on those roads at the same time, it is an intriguing effort,” Points explained.

Published 12-30-2011