We all know somebody --- or perhaps we're that somebody ourselves --- who goes out of their way to avoid making a left turn while driving. The thing is, depending on the intersection, making three right turns instead can often take longer, and be more dangerous, than committing to a single left turn.
But now there's a better way, or at least traffic engineers would like to make you think there is. They're called superstreets, which according to a recent study by North Carolina State University can result in a significant reduction in travel time while also resulting in many fewer collisions, especially those with injury.
"The study shows a 20 percent overall reduction in travel time compared to similar intersections that use conventional traffic designs,” said Dr. Joe Hummer, professor of civil, construction and environmental engineering at North Carolina State and one of the researchers who conducted the study, according to a press release from the university. “We also found that superstreet intersections experience an average of 46 percent fewer reported automobile collisions -- and 63 percent fewer collisions that result in personal injury."
The North Carolina State data was gathered from superstreet intersections in central and eastern North Carolina, the travel time statistics from three superstreets and the collision numbers from 13. The study was funded by the North Carolina Department of Transportation.
How a Superstreet Works
They work like this: Take a busy, four-lane, divided highway intersected by several minor two-lane roads. Say you're on one of those minor roads and want to make a left turn onto the divided highway. In a superstreet scenario you wouldn't have that option. Instead, you'd make a right turn onto the highway and get into one, perhaps two, dedicated U-turn lanes.
The intersection would still require four traffic signals, and most drivers would have to pass through two of them, but the time-consuming left-turn signal would be eliminated.
Superstreets Have Their Disadvantages
Superstreets aren't a common sight as of yet in the United States for some good reasons. Creating one requires laying down one or two new lanes in the highway median, assuming the median has room for them. And some traffic signals would have to be relocated.
Also, superstreets do nothing to address the most dangerous form of left turn --- from a busy highway onto a minor road without a signal, where the driver may be in a dedicated left-turn lane, but is a sitting duck between full-speed traffic moving up behind him on his right and full-speed traffic approaching him on his left.
An Alternative to Roundabouts
Still, the concept of superstreets is appealing to those who dislike traffic circles, or roundabouts, Europe's most popular way of getting around the left-turn problem. Roundabouts have enjoyed some recent popularity in the States, particularly in eastern states like New Jersey where they've been around for a while.
But roundabouts have their own problems. Many drivers don't slow down for them, while others do. They often feature added lanes, which then just as quickly disappear, sometimes without little or no warning. Often these lanes, however many there may be, aren't marked.
And in America, where traffic flow is left up to state or local municipalities, there's been little consistency in their design. In most roundabouts the traffic entering the circle has to yield to the traffic already in the circle, but sometimes it works the opposite way, with the entering traffic given the right of way. Perhaps it's not surprising that so many American drivers hate this traffic feature.
Studies have shown, however --- many studies, over many years --- that roundabouts can improve traffic safety at troublesome intersections rather dramatically. A New York State Department of Transportation study from 2004, for instance, determined that crashes at 35 intersections converted from traditional signals to roundabouts dropped 37 percent, while crashes with injuries fell a whopping 75 percent.
And Then There's the Jug Handle
Drivers have adapted quite well to another left-turn alternative --- the jug handle. In this scenario, motorists on that busy, four-lane divided highway wanting to make a left turn onto a minor road instead pull off to the right onto a dedicated lane that then curves to cross the highway they were just on, with a signal.
Again, these intersections have been in use in states like New Jersey for some time and seem to work quite well, but require ample room off the right side of the highway to build the jug handle, which is not always available. And too, if the minor road is not in fact that minor a backup can result where the jug handle merges onto the minor road, sometimes extending all the way back to the divided highway if the jug handle isn't long enough.
Maybe, for those with a left-turn phobia, just making those three right turns is still the best way to go.
