Forced Turn Islands are raised islands that block certain movements on approaches to an intersection. They are good for ocal street connections to main streets where through traffic volume along the continuing local street is a problem, and main streets where left-turns or through movements out of the side street are unsafe.

Advantages:

• Forced Turn Islands can improve safety at an intersection of a local street and a major street by prohibiting dangerous turning movements
• They reduce traffic volumes

Disadvantages:

• If designed improperly, drivers can maneuver around the island to make an illegal turning movement
• They may simply divert a traffic problem to a different street

Effectiveness:

• Average of 31% decrease in traffic volume, or a decrease of 1167 vehicles per day (from a sample of 10 sites; average includes various types of volume control measures)

Similar Measures:

• By placing a barrier across only one stem of the intersection, you have a Full Closure
• By placing a barrier only half-way across a street along only one stem of the intersection, you have a Half Closure
• By placing the barrier diagonally through an intersection, you have a Diagonal Diverter
• By restricting turning movements using an island on the main street, you have a Median Barrier

Cost Estimate(s):

• $3,000 - 5,000