Vikash V. Gayah, an Associate Professor of Civil Engineering from Penn State, said that removing left turns will improve traffic and promote a safer city driving experience.
He got his inspiration from UPS, which changed its delivery routes in 2004 and reduced travel times, fuel consumption, and carbon emissions. The company claims that they were able to save 10 million gallons of fuel, 20,000 tons of carbon emissions and enabled their drivers to deliver 350,000 more packages, according to The Conversation.
Gayah thought that if it worked for UPS, perhaps it could also work in cities. He studied traffic flow in urban streets and transportation safety for almost ten years, and part of his studies focus on how streets should be organized and managed.
He found that eliminating left turns at intersections with traffic signals could reduce traffic and is safer for driving. He and his team developed a way to know which intersections should restrict left turns to improve traffic.
No Left-Hand Turns Policy of UPS
UPS is one of the largest delivery services in the world and also has one of the largest fleets of delivery vehicles, with over 96,000 vehicles worldwide. They are attached with a tracker that does not only tells their location but also the time they traveled, at which speed they are traveling, the routes the driver takes, and others.
According to GovLoop, UPS discovered that drivers spend a lot of their time idling while waiting to make left turns which resulted in higher gas consumptions and longer trip durations. They also noted that making left turns also poses a greater risk.
So, UPS first ran experiments that replaced left turns with right turns, which showed that drivers saved time, money and reduced their carbon emissions. Today, UPS drivers only make about 10% left turns, saving 10 million gallons of fuel.
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What's So Bad With Left Turns?
Intersections are dangerous because that is where crashes usually happen that result in major injuries, including fatalities. Traffic signals are very helpful because it helps direct the traffic. It is much easier if a left turn signal does not occur because vehicles would not have to cross oncoming traffic, making intersections complicated.
Vehicles could wait until there is a gap with the oncoming traffic, or a green arrow to the left could also be an option. However, Gayah wrote in The Conversation that both methods are deemed unsafe. It is estimated that 61% of all interaction crashes involve a left-hand turn.
Will Eliminating Left Turns Improve Traffic?
The team believes that the best option for safer city driving is to reduce left turns at intersections. Some cities have started limiting left turns to improve traffic flow, like San Francisco, Salt Lake City, Alabama, Birmingham, Delaware, Wilmington, and many others.
However, there is a downside to limiting left turns in intersections. It increases the time to travel as drivers are forced to travel at longer distances. For instance, it might take three more right turns to get to a place when avoiding a busy street when it could have been easily done with just one left turn.
On the other hand, studies suggest that eliminating left turns on grid-like street networked would only require an additional block, and a smooth traffic flow could offset this.
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