On the road: Connect The Dots

Las Vegas roadways are literally overrun with them. And motorists heed them most when they run them over.

They are called "Botts Dots," and they divide the lanes on freeways and streets. Painted lines can still serve this local function, but the dots have become the more frequent divider.

Also referred to as "pavement markers" or "buttons" by city of Las Vegas traffic engineer O.C. White, the dots can be circular or roughly square. Most are ceramic, however certain ones made from a polymer can be used as reflectors.

A series of white buttons divides two or more lanes going in the same direction, while yellow buttons form the median between two directions.

By White's estimation, it was about five years ago that the city started to take on a grand-scale dot matrix for its streets.

"It was 1998 when I first came here, and they were experimenting," White said of the city engineers. "They were trying out different materials on the roads, finding products that would work well here.

"We adopted a list of products, including the dots, and we knew a company that was working on them, trying to improve the life span."

Longevity has always been the key. In Las Vegas, the roads must contain markers that can endure the pounding of the desert sun, as well as the pounding weight of desert roadsters.

White estimated it was about eight to 10 years ago that the city used the last of its supply of oil-based paint for lane-drawing. After that came the environmentally friendlier water-based paint. The new paint didn't hold up well.

"It was a replacement for the oil-based paint," White said. "We found out that we had to repaint the lines much, much quicker than we used to."

White said the dots can last five to 10 years, so they definitely leave painted lanes hung out to dry. Two of the city's goals are to minimize road maintenance and traffic disruptions, according to White, so longevity matters.

Most roads in residential areas are exempt from being buttoned up, since they lack the necessary traffic.

"We have a lot of residential streets with no markings at all," White said. "Once you put down markings, it makes people uneasy because they think their street is a main thoroughfare.

"There are a few streets with a little more traffic than normal. On Stewart Avenue, between Maryland (Parkway) and Eastern (Avenue), we have buttons on that and it's a two-lane street."

The process of laying the dots down involves measuring the lanes, spraying paint on the road to mark where the dots will be placed, then putting down a hot, tar-like liquid called "bituminous" where each dot goes.

The substance acts like a glue.

"It takes one hour to two hours to heat up the bituminous in a big kettle machine -- we get it up to 400-450 degrees," said Denny Gartland, sign and field marking manager with the city of Las Vegas. "That's where a lot of the labor comes in."

Placing each dot adds to the time-consuming procedure, said Gartland, since, "We just walk along, and put them down one at a time ... you can only move as fast as you pour this stuff and walk along."

Another impediment is temperature. The bituminous dries faster in cooler climates. In Las Vegas, drying time may be slower than it would be for a road in Anchorage, Alaska.

Gartland cited the difficulty of placing buttons on a curved road, such as Buffalo Drive near Elkhorn and Farm roads.

"If you're doing a straight road, you can pull the rope straight, but on a curved road, you pull out the rope and make it the same curvature as the road," he said. "We have the same problem when we put buttons in the middle of an intersection: we have to figure out the curvature of the turn to guide people through the intersection."

Gartland recalls when paint was used and a city crew could "stripe" several miles in one day. With the dots, he estimated that only one-half to one mile can be covered in a single day. White stated that the removal of the dots, when the street is "rejuvenated," also lacks expedience.

Still, at roughly 50 cents apiece, the dots are economically feasible and a practical alternative to painted lines.

"The dots have been working fairly well," White said. "We've had good luck with them lasting a long time."

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