What are J-Turns?
The J-turn is an alternative to traditional roadway intersections on a four-lane highway. Instead of motorists crossing fast-moving lanes of traffic to get to the opposing lanes, drivers at a J-turn intersection turn right in the same direction of traffic, merge into the left lane, and then make a u-turn in the direction they intend to travel. Although drivers will have to travel slightly further to get where they want to go, using J-turns can take the same or less time than trying to wait for a safe and appropriate gap to cross traffic.
The point of these turns it to greatly reduce – or even eliminate -- a significant number of severe crashes common when drivers must cross-over busy highways to reach another road.
In the J-turn design drivers turn right in the same direction of traffic, and merge safely into the left lane to prepare to make a left turn in the direction they intended to travel. This option uses an extended deceleration lane, basically adding a third lane on the highway to allow traffic making a left turn onto opposing lanes to safely pull off the mainline, out of the way of high speed traffic. In addition, acceleration lanes may be constructed to allow traffic an opportunity to gain speed after turning onto the highway.
How do J-turns enhance safety?
J-turns have proven to be a safer alternative to a traditional roadway intersection on a four-lane highway because they eliminate or greatly reduce right-angle crashes, the crash tpe most responsible for fatalities and serious injuries at intersections. In fact, the installation of J-turns at similar intersections throughout Missouri and the nation have shown a substantial decrease in fatal and serious injury crashes. Basically, they eliminate the need for motorists to cross the high speed lanes of traffic to get to the opposing lanes.
Studies done by the National Cooperative Highway Research Program show J-turns provide significant reduction in right-angle, “far” side crashes.
How do you drive a J-Turn?
The J-turn eliminates the cross-over between the four-lane divided highway. In the J-turn design, drivers turn right in the same direction of traffic, an merge safely into the left lane to prepare to make a left turn in the direction they intended to travel. This option uses an extended deceleration lane, basically adding a third lane on the highway to allow trafficmaking a left turn onto opposing lanes to safely pull off the mainline, out of the way of high speed traffic.
Recent statistics about J-turns:
A recent study conducted by the University of Missouri shows that implementing the J-turn design at intersections of high-speed rural expressways and minor roads results in fewer accidents than those that are controlled by two-way stops.
Researchers assessed five different J-turn intersections in Missouri:
- The J-turn design resulted in a 34.8 percent reduction in crash frequency for all crashes
- A 53.7 percent reduction in crash frequency for all injury and fatal crashes.
- Disabling injury crashes decreased by 86 percent and minor injury crashes decreased by 50 percent.
- Since the J-turns have been in place, none of the five study sites had a single fatality accident.
- One of the most severe crash types, the left turn, right angle crash, was completely eliminated by the J-turn.
Missouri currently has 19 J-Turns and anticipates building more in the future.
How can I learn more?
You can learn more by contacting Traffic Liaison Engineer John Miller at (573) 526-1759 or by email John.Miller@modot.mo.gov.