What is a Median Left-Turn?
Median Left-Turn designs are unique to Texas. Where a Median Left-Turn design is in place, left-turns at the intersection are not allowed. Instead to turn left you must first turn right, and then make a U-turn at a median crossover, guided by the sign like the ones shown to the right. Median Left-Turns have gained acceptance throughout the United States as an effective way to reduce left-turn stopped delays, traffic congestion, and collisions.
Why has the City of Plano adopted this design?
Years ago Plano City Council decided to remove from consideration the construction of grade-separated intersections at locations formerly planned for constructing overpasses. Whenever traffic congestion levels rise to unacceptable levels at these locations, the City of Plano Transportation Division will consider incorporating conventional designs or more effective designs like the Median Left-Turn. Research and experience have shown the Median Left-Turn design relieves congestion, and increases traffic flow and safety by reducing the number and severity of intersection-related crashes. An internal evaluation of this design determined high performance can be maintained under certain conditions that prohibit left-turns on one road and not the other.
How do Median Left-Turns compare in efficiency to conventional intersections?
This innovative design provides 20 to 50 percent greater capacity than direct left-turns. The design reduces the average delay for left-turning vehicles and through-traffic.
What is the largest vehicle that can use a Median Left-Turn crossover?
Plano designs the crossover median to accommodate large trucks that are 55 feet long with a 45-foot turning radius.
What about drivers who are not familiar with Median Left-Turns?
Research of other agencies using this design determined that no significant problems have been detected to date. Non-familiar users do not appear to have difficulties using this design.
What about pedestrians and bicycles?
Median Left-Turns increase pedestrian/bike safety. When using this design, non-motorized users are able to cross the road in a two-step manner. They cross the first half of the road, wait at the median and cross the second half of the road when safe to do so. By eliminating left turn movements, more time can be given to pedestrian crossing time.
What’s the effect on traffic collisions?
Research shows a 30 to 60 percent reduction in overall traffic collisions. The greatest reductions are those involving left-turn maneuvers (rear-end, head-on and failure to yield to oncoming traffic). Non-left-turn rear-end collisions may increase slightly.
What are the minimum requirements for using a Median Left-Turn design?
There are no specific requirements for this design. The design has been used successfully on roads carrying between 10,000 and 100,000 vehicles per day.
How many Median Left Turn locations will be implemented in the City of Plano?
The Median left Turns will be implemented at three locations:
Legacy Drive @ Preston Road
Plano Parkway @ Preston Road
Spring Creek Parkway @ Coit Road