When you see a merge sign, follow CDOT’s advice and use the zipper method of merging, that is, stay in your lane until the road narrows, then merge, alternating with traffic in the other lane.

Colorado is one of an increasing number of states asking drivers to wait until the lanes narrow before attempting to merge, Michael Hawthorne writes for Fox News Magazine. The other states include Minnesota, Missouri, Kansas, Washington, and Colorado. As Hawthorne writes:

We’ve always assumed that those people who cut the line and wait until the last second to merge are rude, inconsiderate jerks, but now it appears that the jerks may have been us all along.

For a decade, the Colorado Department of Transportation has been suggesting drivers use what it calls the “zipper method” of merging when traffic is especially heavy, Cassa Niedringhaus writes for The Coloradoan. Drivers from each lane should take turns merging at the point where the roadway narrows.

When drivers merge too early, it leaves an entire lane unused. The zipper method can decrease congestion by up to 35%. However, drivers are mostly ignoring CDOT’s advice. CDOT spokesman Bob Wilson told The Coloradoan that it takes a long time to change people’s driving behaviors.

It also is safer for drivers to use the zipper method, according to an article in West Central Tribune. It works best, especially in heavy traffic, because:

  • It reduces the difference in speeds between the two lanes
  • It reduces the length of the backed up traffic by up to 40%
  • It reduces highway interchange traffic
  • It produces a sense of fairness because all lanes are moving at the same speed (seeing a car zipping ahead in the empty lane can cause road rage, and possibly an auto accident)

Here is a video that shows the zipper merge:

A Chance to Practice the Zipper Merge

In other Colorado highway news, CDOT is doing roadwork on weigh stations at the Interstate 70/Dumont Port-of-Entry facility, replacing portions of the weigh-in-motion system. The roadwork will cause the closure of one lane on westbound I-70 (west from the Exit 235-Dumont for about half a mile), during the following time periods:

  • From Sunday, Oct. 23, at 4 p.m. through Friday, Oct. 28, at 9 a.m.
  • From Monday, Oct. 31, at 7 a.m. through Friday, Nov. 4, at 9 a.m.

During working hours, the speed limit will be set to 55 miles per hour.

The $670,000 project includes the installation of new scale frames and weigh plates, bolts, and loop detectors, as well as the replacement of about 375 feet of concrete pavement. The system weighs trucks and other commercial vehicles in the right lane as they drive at normal traffic speeds. As they drive over the scale, weigh-in-motion (WIM) systems record the axle and gross vehicle weights.

CDOT project engineer Scott Burger said the existing weighing system helps all drivers on the roads. It reduces congestion because it significantly reduces the number of commercial motor vehicles that must exit the roadway to be weighed and checked at the port. Burger said:

Trucks don’t back into the Downieville westbound off-ramp and they don’t wind up slowing down traffic by re-entering I-70 after stopping at the port-of-entry.

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