Beginning Tuesday, the Idaho Transportation Department will lower the speed limit from 55 mph to 45 mph on the 2.2-mile stretch of State Street between Glenwood Avenue in Boise and Idaho 55 in Eagle to improve safety and traffic flow.
There are several schools, businesses and side streets along this section of State Street," said ITD southwest Idaho Traffic Engineer Kevin Sablan. "With traffic traveling at 55 mph, it was becoming increasingly difficult for motorists to safely enter and cross the highway.
Idaho State Police, local law enforcement agencies and area city leaders met with the transportation department in early June to discuss the change and express support.
There have been 170 crashes on that stretch of road in the past five years.
This stretch of roadway has nearly 75 business and resident approaches onto State Street, more than 15 times as many as are recommended for this type of roadway.
Safely navigating the large number of entrances and exits requires a lower speed on the roadway. In addition, the highway is lined with power poles and mature trees that tightly border the road, leaving an inadequate shoulder for recovery and reduced sight distance for drivers, especially on those side streets, according to ITD.
ITD traffic engineers set the limit at the speed at which 85 percent of the traffic is driving to determine a safe and reasonable speed for a given road section, in accordance with federal safety guidelines. According to research, setting a speed limit according to that 85th percentile produces the fewest crashes.
On Thursday, ITD will increase the speed limit to 50 mph on the 4-mile section of Chinden Boulevard/U.S. 20/26 between Coffey Street west of Garden City and Eagle Road.