The Science of J-Turn Intersections

There is a proposal to put in a J-Turn intersection on a major highway near where I live.  The intersection in question is one that has had increased traffic over the years but currently doesn't have a light or any other easy way for traffic crossing or turning onto the highway to do so safely.  The easy, and cheapest, solution is a traffic light.  But is this the best solution?  Since a J-Turn intersection is not common in this area, and given it's a change to the intersection, naturally there is a ton of outrage at this proposal.  So what is a J-Turn intersection?  The image below describes these intersections very well and comes from the Missouri Department of Transportation.

J-Turn intersection (Missouri Department of Transportation).

A J-Turn intersection creates a far safer method of crossing the highway and turning onto the highway, while at the same time keeping traffic flowing.  A stoplight slows traffic down, but this is not necessarily a good thing.  There's no way to completely remove traffic accidents, but the goal should be to limit the possibility of traffic accidents as much as possible.  J-Turns are not just a crazy idea someone came up with.  They've been researched extensively and you can read more about the safety of these intersections by going to the Missouri Department of Transportation link below.  The evidence is quite clear they reduce traffic accidents.

Evidence of J-Turn Safety

Here's the deal.  The particular intersection where I live is one I've crossed many times and one that can be very dangerous at specific times of the day.  I want something done with this intersection, but the last thing I want is a stoplight.  More stoplights halt traffic flow and increase driver angst/anger.  This results in drivers getting more frustrated with additional stops and additional lost time.  This increases poor decision making and results in drivers taking risks to beat a red light to save time.  This puts drivers and bystanders in a dangerous position.  Why put in a stoplight if there is a far more effective method to increasing safety AND keeping traffic flowing at the same time?

There are additional factors to traffic flow design as well.  Although safety is often the primary factor, traffic flow plays a big role in economic development of an area.  There are many times I've chosen a particular gas station or store to stop at versus another based on the ability to get there given poorly designed road access.  Keeping traffic flowing, yet safe, can increase economic development in an area. 

Sure, a stoplight could be put up, but this isn't always the best decision.  It's important to recognize that many factors must be considered when re-doing an intersection.  Even if the only factor is safety, stoplights do not always increase safety, or if they do, there may still be other intersection designs that increase safety beyond what a stoplight can do.  Another intersection option is a roundabout.  I LOVE roundabouts!  They keep traffic flowing and have been shown to work in high traffic areas.  They are becoming more common in the U.S., but they are all over Europe and they work extremely well! 

I'll end with this.  It's easy to be outraged because a change is made to traffic intersection.  But that outrage is often not founded with solid evidence.  When designing roads and intersections, emotion needs to be tossed out the window and replaced with solid research and evidence of what works best.  Before being outraged when presented with a change, think through what this change means.  Too often people are outraged at what helps them and society.