The Zipper Merge: Could “Impolite” Drivers Be In The Right?

highway driving safety zipper merge

What Is The Zipper Merge?

The zipper merge is one way that drivers can merge from one lane to another if they notice a lane closure is coming up. Often times lanes close on highways or city streets due to construction or traffic accidents, and these areas can cause headaches for all drivers on the road.

With this merged system, drivers are able to utilize both lanes of traffic until the defined merge area. At the point where the lane ends, drivers will take turns alternating through a “zipper-like” pattern where cars funnel into the open lane.

The Department of Transportations recommends this method for several reasons, including:

  • Can reduce the overall length of traffic by up to 40%.
  • Reduces lane speed differences.
  • Improves throughput of traffic, even in heavily congested areas.
  • Reduces congestion on highway exchanges.
  • Reduces accidents in construction zones.

Even though some drivers think that passing drivers are personally insulting them, the truth is that in heavily congested, slow-moving traffic situations drivers need to do everything they can to keep traffic moving. This is not only in their personal best interest, but it is also in the interest of all drivers on the road.

Zipper Merge Vs. Early Merge

When most drivers first see a “lane closed ahead” many people try to merge into the appropriate lane too quickly. This type of merging pattern is called the “early merge,” and it is one of the most common driving patterns among American drivers.

The process of merging early requires both drivers who are joining and drivers who are allowing other cars into their lane to slow down. This driving behavior can lead to unexpected lane switching, traffic flow issues, and even increase the likelihood of serious crashes.

The best way to keep traffic moving and reduce the likelihood of causing a dangerous situation is to use both lanes for as long as possible and then alternate merging vehicles into the open lane using the “zipper merge.”

While this sounds counterintuitive, there has been much research around this issue to show that utilizing both lanes for as long as possible can dramatically increase the throughput of a given area.

Most drivers choose the “early merge” approach when they see a lane closed ahead because they want to be nice and don’t want to “cheat” other drivers. However, the truth is that it is safer and more efficient to remain in your current lane until you reach the defined merge area and then take turns merging into the open lane.

Why The Zipper Merge Isn’t Perfect

While the zipper method is the most efficient and safest way to merge two lanes, it is not perfect. Even though the data shows this method is the best way to merge, the human sense of being “cheated” by a driver passing them in a lane that is about to end often makes the zipper merge inefficient.

Here are a few of the most notable factors that reduce the effectiveness of the zipper merge and could cause some drivers to be angry when seeing other drivers engaging in this driving patter. 

1. Impatient Motorists

When people merge early, they are stuck in a backed up and slow moving lane. After sitting in that lane for an extended period of time, many drivers become stressed and can develop road rage.

It is important to note that while drivers in the open lane technically have the right of way, all merging etiquette laws suggest that drivers should let merging vehicles into their lane if safe and appropriate.

2. “Entitled” Drivers

Many drivers think that when they see a “lane closed ahead” sign that everyone should move to the open lane as soon as possible. This mentality can breed a sense of entitlement for drivers in the open lane, and as result drivers who are looking to merge could face a dangerous situation is they are not allowed into the open lane.

If no one lets the driver in from the closed lane, that driver might be forced to act aggressively, and this could cause an accident.

3. Road Rage

Road rage can hit the nicest people and push someone into a sense of “warrior justice.” Sitting in traffic that is not moving can raise anger quickly, and this is only multiplied in a person’s mind when they see cars speeding by them in a lane that is soon to close.

As a result, drivers who have had to sit through the merging traffic are less likely to allow other drivers into their lane.

4. A Lack Of Sharing Increased Traffic Congestion

Due to the above errors in how we interpret merging traffic, many people will choose to either join early or not let merging traffic into their lane. Both of these situations can result in bottlenecks and traffic buildups.

Instead of utilizing both lanes for maximum throughput, many drivers will try to take the “high road” by merging early, even though this will only increase the overall pain everyone feels.

The Verdict Is Still Out On The Zipper Merge

Despite the growing popularity of the zipper method among highway officials, some states are hesitant to back the zipper merge. States like California hold that the early merge is the best way to combine two lanes because it does not cause sudden braking or rear-end collisions.

The Federal Highway Administration does not have an official stance on whether states should promote the zipper merge, but there is still lots of research that needs to be done before one method is adopted on a national level.

Either way, transportation experts will need to find a solution that is best regarding efficiency and can be used by drivers who may feel insulted by other drivers who utilize the preferred method!

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Author: Chris Giarratana

Chris is a Digital Media Strategy and AdWords management consultant in Orlando, FL. He develops marketing strategies for small businesses, researches emerging technologies, and enjoys studying transportation issues.

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