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February 24, 2008

Highway striping

This is in response to Alan Perry’s concerns regarding striping on I-35 being hard to see during poor weather (2/19, Voices).

As part of the Missouri Department of Transportation Better Roads, Brighter Future program, we are stepping up efforts to provide brighter striping on Missouri’s 32,423 miles of highways.

Interstate and major routes get 6-inch-wide stripes compared to 4, the standard. We use glass beads to reflect the light from your headlights, 12 pounds of beads per gallon of paint, which costs 18 cents per foot.

Water diffuses light going into the bead. Dirt and salt in the water make the problem worse. Snow plows break or shave off beads.

We now use an imbedded tape stripe on interstates to reduce damage by plows, but it costs $6 per foot. Plows can’t get to the stripe, but your headlights can.

This year, we will use beads in our paint that have enhanced wet qualities. Concrete roadways will have a black outline to make stripes stand out.

A dirty, salty moist film adheres to our driving surfaces during the winter months. High speeds make it more difficult for drivers to see the light from dirt-smeared headlights.

Tom Evans
MoDOT District 4 traffic engineer
Lee’s Summit

It is interesting to read the comments about road markings that are difficult to see when rain or snow is on the pavement. Transportation engineers have wrestled with this for years.

Think about it. There are thousands of miles of paved roads with lane markings that experience rain, snow and the abuse from millions of vehicle tires.

During winter, citizens expect chemicals, abrasives, or plows to act upon the pavement providing safer traction for vehicles. All of these conditions interfere with visibility and durability of any available material for line markings.

Ever since autos and paved roads replaced the horse, lines have been painted on roads with tiny glass spheres embedded in the paint film to reflect light from headlights.

Even raised metal snow-plow resistant markers with reflectors were developed for use in the Snow Belt.

Rain and snow still reduces or obscures the visibility of the line regardless of how often it gets restored or what material is used.

Perhaps electronic guidance and positioning systems in vehicles and roads will someday make lane lines obsolete. For now, the obvious and economical solution is to slow down and drive more cautiously on wet or snow-covered roads. No amount of taxation is going to eliminate the precipitation.

James Lee
Kansas City

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