Zipper merge is one way to reduce traffic frustration
Roundabouts promote efficient flow of vehicles
A few simple tips can save you time and reduce frustration in heavy traffic and construction zones, whether during your daily commute or a summer vacation drive.
Here’s the experts’ latest advice:
1. Use the zipper merge.
The quickest, most efficient way to merge for a construction zone probably isn’t what you think it is. The “zipper merge,” in which vehicles run in parallel until one lane physically narrows, is better for traffic flow than when vehicles form a single line early.
Yes, that means the driver you cursed for “cheating” by driving by you in the empty lane after you politely merged to the through-lane a half-mile before the construction zone was helping traffic flow more than you. Sorry.
An increasing number of states encourage drivers to use the zipper merge. Some even created flashing signs showing how and where to merge.
“It’s important to merge smoothly not to make sudden lane changes,” said Teresa Qu, Michigan State University associate professor of urban and regional planning.
2. Don’t weave in traffic. It really doesn’t help.
If you routinely jump from one lane to another to get around a slower vehicle, you save less time than you think and are more likely to add to congestion or be involved in an accident.
David Hyde of public radio station KUOW’S “Sound Qs” program, recounts a commuting comparison in Seattle’s congested traffic. The result: He arrived about a block ahead of, and way more stressed out than, the driver who stuck to a single lane.
Multiple experiments show that highway weavers may save a minute or two in an hour-plus drive. In exchange for that, every lane change can triple the likelihood of an accident, according to a study that also showed that lane jumpers save less time than they think and are usually wrong when they think the next lane is going faster in heavy traffic, according to research by Donald A. Redelmeier and Robert J. Tibshirani of the University of Toronto and Stanford University, respectively.
Lane changes make sense to avoid a line of slow trucks, a single drastically pokey lane pirate, an accident or other obstruction. Otherwise, leave space on the right for entering and exiting traffic and travel in the other lanes.
“Nobody likes to be stuck in traffic, but when you change lanes, you usually realize it’s not moving any better,” MSU’S Qu said. “If you want to arrive earlier, the best thing to do is learn the traffic pattern and leave five minutes earlier.
“Traffic apps like Google Maps and Waze can also provide alternatives that help you save time.”
Apple Maps still needs work, based on my experience on a couple of recent trips.
3. Use adaptive cruise control to end “phantom” jams.
An increasingly common driver-assistance feature can reduce or eliminate the maddening traffic slowdowns in which multiple highway traffic slow, come to a nearly complete halt, and then resume speed for no apparent reason.
New research by Vanderbilt University and Ford shows that using adaptive cruise control can end those “phantom” traffic jams, which frequently coincide with a mild curve on a highway. The slowdowns occur when a single driver brakes, and drivers behind that vehicle overcorrect, braking more and more as the slowdown spreads.
“Every time you brake in traffic, it creates more congestion with a ripple effect downstream,” Qu said.
It’s not uncommon for the cars at the tail end of the phantom jam to come to a complete stop, despite the fact that nothing happened ahead of them.
Adaptive cruise control, which uses radar, automatic brakes and other systems to maintain a set distance from the vehicle ahead, reduces the phantom jams because it only applies brakes when it has to, and is less likely to over-brake than human drivers. It also helps vehicles resume speed smoothly after a slowdown. The experiment used a fleet of 36 drivers in three lanes on a closed high-speed test track.
In experiments on a closed highspeed test track at Ford’s proving grounds adaptive cruise, or ACC, the tail car in each lane slowed by just 5 mph, rather than coming to a complete stop when each driver braked manually.
The result was nearly as good when just one-third of the test vehicles used ACC and the drivers controlled the rest.
“Adaptive cruise control systems don’t get tired or distracted, they’re consistently looking at the vehicle ahead,” said Kane. “Plus, they are programmed to provide more consistent distances between vehicles so they can better respond to the speed and distance of the vehicle ahead,” Vanderbilt civil engineering professor Daniel Work said.
Not all ACC systems are created equal. Some are conservative and leave big gaps between vehicles. They are less suitable for heavy-traffic situations like Ford and Vanderbilt tested.
4. Learn how to drive smoothly through traffic circles
Traffic circles, or roundabouts, are becoming increasingly common, but most drivers don’t know the best way to use them.
The answer: Merge smoothly into the flow around the circle. Don’t stop unless there’s no gap in traffic. Traffic circles were created in Europe to reduce the number of stop signs at intersections and promote traffic flow.
Drivers already in the circle always have right of way, but you can merge into the outside lane while a car goes by in the inner lane. Some traffic circles have more than one lane. Which one you should use depends on how far around the circle you’re going. Use your turn signal to indicate when you’re ready to leave the circle.
One of the great things about traffic circles is that you can always go around again if you miss your exit or accidentally end up in the wrong lane.
“Drive smoothly into the circle,” MSU’S Qu said. “That helps you get through the intersection quickly. It’s a very efficient traffic design.”
Unfortunately, traffic circles were rare when many people learned how to drive, so they’re learning on the road.
Most new drivers learn how to use traffic circles in theory, though they may not get to practice on them.
“Driving tests should require understanding of roundabouts,” Qu said. It’s up to the city and the state department of transportation to educate people.”