8/1/2012
Reed Hollinshead
ITD Communication
208-334-8881
reed.hollinshead@itd.idaho.gov
Speed limit change coming Tuesday to section of State Street for safety and traffic flow
BOISE - To improve safety and traffic flow, the speed limit on 2.2 miles of State Street between Glenwood Avenue and Idaho 55 will be reduced from 55 mph to 45 mph beginning Tuesday (Aug. 7) after the morning commute, the Idaho Transportation Department announced.
"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.
The section in question is the segment of State Street from St. Luke’s and Home Depot (at the Idaho 55 cutoff to McCall) to the Maverik gas station that sits just west of the Walmart at the State and Glenwood intersection.
Click here for map of location.
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.
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.
The posted limit is a maximum speed when there are no obstacles or distractions and the pavement is dry. With icy, snow-covered or slick roads, it is always prudent to travel slower than the allowed limit. The speed-limit guideline is safe and prudent for the conditions.
"Speed-limit signs cannot replace common sense," said Sablan. "They are intended to supplement - not substitute for - the driver's judgment."
Limits help determine a reasonable speed for a particular road under ideal weather conditions. Speed Limits are imposed to assist Idaho law enforcement, and enforcement of the limits by them is essential. Limits encourage better traffic flow by reducing the variances in speed from one vehicle to the next, enhancing free-flowing movement.
In determining speed limits, the investigation involves determining the design of the road and its immediate environment. Engineers analyze items such as lane width, pavement type and condition of the road. They also look at terrain, parking conditions, residential development along the road and the number, width and types of entrances and intersecting streets.
Reducing a speed limit does not necessarily result in safer driving conditions. Reducing the limit below the warranted speed can actually be hazardous and unsafe. Studies show that merely reducing a speed limit has little effect on the speed at which motorists will travel. Furthermore, no published research findings have established a direct relationship between lower posted speed limits and crash frequency.