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Curious Louis: Why are stripes on St. Louis roads so hard to see, particularly in the rain?

Horizontal photo of a cracked and fading yellow road stripe in St. Louis.
Joseph Leahy | St. Louis Public Radio
85 Curious Louis respondents wanted to know why it's often so hard to see stripes and markings on area roads

Driving in the metro area can be difficult when motorists have trouble seeing the lines on the road, especially at night when it’s raining. The issue prompted scores of respondents to our Curious Louis project to wonder why more reflective paint isn't used on local streets. We looked into their concerns and found it’s mostly a matter of rough winters and tight budgets.

"As soon as it snows and the plows go down, all that reflectivity is gone because those beads are being sheared off by the plows."

For the most part, all traffic striping used in the metro area is reflective. Trouble is, it's often just not very effective or durable.

St. Louis uses an acetone-based paint with glass beads embedded on top. St. Louis County and the Missouri Department of Transportation predominantly use water-borne paint with beads. Both techniques are cost effective, but tend to break down within a year or so on high volume roads.

"Oh yeah, it’s a major issue,” said BJ Penick, the estimator for Traffic Control Co., which contracts road surfacing work with MoDOT and county municipalities. “Really, the local and state budgets can’t afford the materials needed in order to combat that,” he said.

An orange truck pushes a plow on a road in St. Louis during a snow storm.
Credit Flickr | Paul Sableman
City plow trucks often remove more than snow off the roads.

Penick said the area’s harsh winter weather makes it even harder to keep road lines bright and reflective.

“Especially after the snow season: As soon as it snows and the plows go down, all that reflectivity is gone because those beads are being sheared off by the plows,” he said.

Diagram of a retroreflective glass bead embedded in paint on a road.
Credit Susannah Lohr | St. Louis Public Radio
Retroreflective glass beads increase the nighttime visibility of road markings by reflecting light back to its source with a minimum of scattering.

Other states like Illinois and Indiana tend to use more high-durability markings such as thermoplastic or epoxy resins, said Penick. Both techniques are more effective, but cost a great deal more as well.

Herculaneum, Festus and Creve Coeur, however, are outliers in budgeting more for their road markings, which Penick said are some of the best in the region. According to Creve Coeur’s civil engineer Rich Berans, the results are worth the costs.

“We found it beneficial to use the epoxy pavement markings,” he said. “They are about four times more expensive than the water-borne [paint] but on low-volume roads like we have on residential streets, the epoxy will hold up for five to six years, maybe more.”

In contrast, St. Louis’ high-volume major roads are typically striped twice a year and minor routes get re-painted at the start of each spring. However, in an email, St. Louis’ Traffic Commissioner Deanna Venker said an unusually wet spring limited how much striping work could be completed on city streets last year.

Despite concerns raised by residents, Venker and many experts agree that diminished road marking visibility is a universal issue.

“My experience is the same whether I'm on routes in the county, city or state (even across the river). At night and in the rain, we have diminished visibility across the board,” said Venker.

“Unfortunately the solutions at this time are very pricey in a climate that leaves [transportation departments], cities and counties in a holding pattern.”  

Follow Joseph Leahy on Twitter: @joemikeleahy

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