Excellence in Transportation Award:
Maintenance and Operations
Winner: Island Park Road Shade Modification Project

ITD District 6
Karen Hiatt (ITD District 6)
Wade Allen (ITD District 6)
Ron Atchley (ITD District 6)
Ken Hahn (ITD District 6)
Eric Verner (ITD District 6)

In the summer of 2010, the Idaho Transportation Department, District 6 (District) operations and maintenance section became timber buyers – log barons, treading in the footsteps of Paul Bunyan. Although they left the “heavy lifting” to professional loggers, buy a timber sale they did. The purpose: to clear a wider swath in the forest along US 20 in the Island Park area of Eastern Idaho. The project goal: to remove or reduce trees shading the roadway that contributed to winter road icing.

The District is submitting this Excellence in Transportation Award application for our
innovative use of GIS technology, coordination and cooperation we garnered with the US Forest Service, and their help in our administering and bidding the work.

Innovation/Context Sensitive Solutions:
The project traverses an important recreational area that is considered a gate-way to
Yellowstone National Park. US Highway 20 is the main access road to numerous City of Island Park summer home areas, the internationally known trout fishery of the Henrys Fork of the Snake River, Harriman State Park and, as mentioned the western access into Yellowstone Park.

The entire Island Park area is also a major ecologically important piece of the Greater
Yellowstone Ecosystem, home to moose, black and grizzly bear, and is an important migration corridor for Elk to and from Yellowstone. Most of the property adjacent to US 20 is publically owned and managed by the US Forest Service. The forests have been heavily managed by the Forest Service over the past 50 years to replace bug killed stands with healthier replacement stands of lodgepole pine, so the forested areas along US 20 contain a mix of age classes of a few years to mature stands of 100 year old trees. To say the least, any roadside vegetation management is sensitive to many users in this region, so our project had to address these concerns.

The District was concerned that the project would be controversial given the setting and
context – should we or would we be allowed to cut any trees? To address this we wanted to be sure we made a strong case, supported with data, that there would be benefits associated with the project. The District applied the three-dimensional
capabilities of GIS to the problem. We developed a GIS model, using existing GIS tools in
the ArcMap software application from ESRI.

The model uses a ground elevation model, adds tree height within tree canopy boundaries to the bare earth elevations and then uses the Solar Analyst tool in ArcMap to calculate the duration of sunlight reaching the road surface. The model is able to model specific calendar days, times within a day, and the user is able to run any number of tree clearing scenarios to predict changes to the existing lighting condition over the entire project area.

The model results for the project area indicated that clearing both sides of the road to the 100’ right of way limits would increase the duration of sunlight hitting the road in the winter. Clearing beyond the 100’ limit also increased sunlight, but due to the context and additional environmental constraints, the District chose to pursue clearing to the right-of-way line and no more.

Published 5-6-2011