| |
Missouri Department of Transportation

Social Media Facebook Twitter Flickr Instagram YouTube RSS

J-Turn Banner

 

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 Safety Engineer Jon Nelson at (573) 751-1157 or by email Jonathan.Nelson@modot.mo.gov.

 

Traffic using a J-turn has a dedicated left turn

lane to safely pull out of mainline traffic.

 

Jturn without accel and decel lanes

Example of J-Turns

 

Click here to see the J-turn at U.S. 50 and Highway 58.

display

Check out this diagram that shows conflict points

before a J-turn and after.

Traffic Conflicts

Example of J-Turns with Accel and Decel Lanes
(only used as needed)

County Location Date Completed
Macon US 63 and RT M Fall 2014
Randolph US 63 and RT B Fall 2014
Johnson US 50 and MO 58 2014
Jefferson Rt M by Old Lemay Ferry Rd 2007 (3rd quarter)
Jefferson MO 30 before and after Upper Byrnes Mills 12-Dec
Cole US 54 and Heritage Hwy/Buffalo Rd 12-Jul
Cole US 54 and Honey Creek 11-Nov
Cole US 54 and Route E 11-Oct
Cole US 54 and Route CC 12-Aug
Boone US 63 and Hinton/Calvert Hill 2014
Boone US 63 and Route AB 12-Nov
Boone US 63 and Bonne Femme 12-Nov
Boone US 63 and Liberty/Peterson Ln 14-Jul
St Clair MO 13 and Old MO 13/CRD 364 2009 (summer)
Taney US 65 @ Rochester 12-Dec
Dallas US 65 @ County Rd 65 9-Nov
Dallas US 65 @ MO 38/MO TT 9-Nov
Dallas US 65 @ MO 215 9-Nov
Dallas US 65 @ RT AA 9-Nov
About Us
How Do I...
Contact Us
Missouri Department of Transportation
Central Office
105 W. Capitol Avenue
Jefferson City, MO 65102
1-888-ASK-MODOT (275-6636)
1-866-831-6277 (Motor Carriers Services)
Driver's License Offices
horz_bar
| | |
Missouri State Government
© 2013 Missouri Department of Transportation. All Rights Reserved.   Privacy Policy.
 
 
 
 
RSS FeedYoutubeBlogFlickrTwitter Facebook