Why Jerk Drivers Who Merge at the Last Minute Are Actually More Efficient


Merging on the highway can be a fraught task. Most people do it the polite way: merging over into the lane as soon as possible, forming a polite line of people waiting to get off the highway or move out of a closed lane. But there’s always that one jerk who speeds ahead of the line of slowed traffic, merging into the lane at the last second possible and cutting ahead of the entire line of cautious drivers who merged a mile back. While we may resent those drivers, according to HowStuffWorks, this aggressive style of merging is actually the most efficient way to keep traffic moving.

The last-minute system, dubbed the “zipper merge,” suggests that all drivers wait until they’re almost at the fork in the road or start of the closed lane to merge over. Instead of creating a long line of cars at a standstill in the right lane, waiting until the last second maximizes road capacity, since cars are moving in both lanes. It also makes the road safer. Don’t believe it? Watch the principle at work in the animation below.

Traffic studies prove that the zipper merge is the most efficient way to keep a road moving. Instead of one lane of traffic whizzing by while the other lane slows down considerably, both lanes slow down slightly, and overall, the slowdown is more equitable across both lanes. According to the Minnesota Department of Transportation, it can reduce the length of backed up traffic by up to 40 percent.

But that assumes that every driver adopts the zipper merge. Unfortunately, it’s very hard to convince a whole society of drivers to suddenly change their behavior. Even if zipper mergers are technically correct, when the whole rest of the highway is operating under the belief that merging as soon as possible is the correct and polite way to go about dealing with a lane closure, that one guy merging at the last moment just looks like a jerk. The system only works if everyone plays by the same rules.

Some transportation departments have tried to encourage drivers to adopt the practice, putting up signs near road closures that ask people to “merge here,” nudging them to wait just a little longer before they get over.

Merging late may go against our very nature, however. Many people tend to “pre-crastinate,” according to one 2014 psychological study, trying to get a task out of the way as soon as possible even when doing so goes against our best interests. Penn State researchers found that when asked to complete the basic task of carrying buckets from one end of an alley to the other, people were willing to do more work rather than delay completing a basic task until the last second. Many participants opted to pick up a bucket closer to them, even when it meant they would have to carry the bucket farther, rather than waiting to pick up a bucket closer to their end goal.

So, it may be no surprise that the zipper merge hasn’t caught on, at least in the U.S. But at least now you can feel justified being that one last-minute merger.

[h/t HowStuffWorks]

Sydney Airport's New 'Quiet' Terminal Helps You Relax Before a Flight


Picture this: You’re at the airport at 6 a.m., waiting in a too-long line for coffee, and announcements are blaring over the intercom. They’re loud, they’re annoying, and they won’t stop coming.

Fortunately for travelers Down Under, one airport is putting an end to the insanity. As Lonely Planet reports, Sydney Airport is the latest transportation hub to introduce a “quiet terminal” concept. Airport officials promise to broadcast only the most important announcements throughout the T1 international terminal.

“Passenger announcements have been significantly reduced, with boarding call and final call announcements confined to gate areas only,” the airport states on its website.

While this is good news for people who resent the constant reminders, travelers who have a habit of dawdling around in airport shops and losing track of the time will need to be more vigilant. In lieu of announcements, flight information will be provided on screens stationed throughout the terminal.

Airports in Singapore, Dubai, Hong Kong, and Helsinki have undertaken similar measures to cut down on noise and promote relaxation. After all, vacation starts at the airport.

[h/t Lonely Planet]

What Would Happen If a Plane Flew Too High?


Tom Farrier:

People have done this, and they have died doing it. For example, in October 2004, the crew of Pinnacle Airlines 3701 [PDF]  was taking their aircraft from one airport to another without passengers—a so-called "repositioning" flight.

They were supposed to fly at 33,000 feet, but instead requested and climbed to 41,000 feet, which was the maximum altitude at which the aircraft was supposed to be able to be flown. Both engines failed, the crew couldn't get them restarted, and the aircraft crashed and was destroyed.

The National Transportation Safety Board determined that the probable causes of this accident were: (1) the pilots’ unprofessional behavior, deviation from standard operating procedures, and poor airmanship, which resulted in an in-flight emergency from which they were unable to recover, in part because of the pilots’ inadequate training; (2) the pilots’ failure to prepare for an emergency landing in a timely manner, including communicating with air traffic controllers immediately after the emergency about the loss of both engines and the availability of landing sites; and (3) the pilots’ improper management of the double engine failure checklist, which allowed the engine cores to stop rotating and resulted in the core lock engine condition.

Contributing to this accident were: (1) the core lock engine condition, which prevented at least one engine from being restarted, and (2) the airplane flight manuals that did not communicate to pilots the importance of maintaining a minimum airspeed to keep the engine cores rotating.

Accidents also happen when the "density altitude"—a combination of the temperature and atmospheric pressure at a given location—is too high. At high altitude on a hot day, some types of aircraft simply can't climb. They might get off the ground after attempting a takeoff, but then they can't gain altitude and they crash because they run out of room in front of them or because they try to turn back to the airport and stall the aircraft in doing so. An example of this scenario is described in WPR12LA283.

There's a helicopter version of this problem as well. Helicopter crews calculate the "power available" at a given pressure altitude and temperature, and then compare that to the "power required" under those same conditions. The latter are different for hovering "in ground effect" (IGE, with the benefit of a level surface against which their rotor system can push) and "out of ground effect" (OGE, where the rotor system supports the full weight of the aircraft).

It's kind of unnerving to take off from, say, a helipad on top of a building and go from hovering in ground effect and moving forward to suddenly find yourself in an OGE situation, not having enough power to keep hovering as you slide out over the edge of the roof. This is why helicopter pilots always will establish a positive rate of climb from such environments as quickly as possible—when you get moving forward at around 15 to 20 knots, the movement of air through the rotor system provides some extra ("translational") lift.

It also feels ugly to drop below that translational lift airspeed too high above the surface and abruptly be in a power deficit situation—maybe you have IGE power, but you don't have OGE power. In such cases, you may not have enough power to cushion your landing as you don't so much fly as plummet. (Any Monty Python fans?)

Finally, for some insight into the pure aerodynamics at play when airplanes fly too high, I'd recommend reading the responses to "What happens to aircraft that depart controlled flight at the coffin corner?"

This post originally appeared on Quora. Click here to view.