Idaho sets start date of faster speeds, continued differential

By Keith Goble, Land Line state legislative editor | 7/15/2014

A planned speed limit increase on some stretches of Idaho interstates is back on.

The Idaho Transportation Board voted unanimously on Friday, July 11, to endorse a change that will increase speeds for cars and trucks by 5 miles per hour.

Idaho law authorizes motorists to travel 75 mph on rural interstates. In 1998, large truck speeds were dropped from 75 mph to 65 mph. Speeds are 65 mph for all vehicles on state highways.

In early August, speeds are set to increase to 80 mph for cars and 70 mph for trucks on most of Interstates 15, 84 and 86. The boost in speeds was set to take effect July 1, but in the days leading up to the switch the agency announced that the implementation mostly in southern Idaho had been delayed to review input about the change.

The state’s Transportation Department completed the review of speed studies, crash analysis and engineering review, which was required in a bill signed into law in March by Gov. Butch Otter. Findings were presented last week to the Idaho Transportation Board in Coeur d’Alene.

“The board considered all of the comments received, reviewed the engineering study, discussed concerns, and concurred with the ITD recommendation,” stated ITD chief of operations officer Jim Carpenter.

The Owner-Operator Independent Drivers Association is opposed to speed differentials. Association officials say the only speed limit policy that makes sense is to have all vehicles traveling at or near the same speed to minimize interaction between vehicles.

The speed limit in the urban areas of the Treasure Valley, between Caldwell and east Boise as well as through Pocatello and Idaho Falls, will remain at 65 mph for all vehicles.

The department continues to study I-90 in northern Idaho for potential increases.

The law also allows the ITD to boost speeds on state highways for all vehicles to 70 mph. Changes on affected roadways will happen at later dates as speed studies are completed.

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