Not Fade Away

Pavement markings often consistently face the same problem--they wear out, making it difficult for motorists to determine the traffic lanes or other right-of-way spaces. Not only does the faded striping affect these rights-of-way, it also is used in applications for pedestrian crosswalks and parking spaces, both of which necessitate clear pavement marking and high retroreflectivity.

As is the case in many aspects of the transportation industry, thousands of hours of research and development have been invested in order to revolutionize the pavement marking technology currently employed in many areas in North America.

A new liquid pavement marking system is now available that is brighter and more durable than other liquid systems. It also dries in minutes and can be applied at lower temperatures.

Manufactured by 3M, the Liquid Pavement Marking System provides about three times the initial reflectivity of conventional markings. Available in white and yellow, the pavement marking system is designed for use on roadways where drivers need clearer delineation and better contrast between the markings and road surface.

According to the manufacturer, the system is unique because it uses microcrystalline ceramic beads that have twice the crush strength of standard glass beads. These beads are incorporated into an optical package called elements. The larger, more durable elements maintain their ability to reflect at brighter levels, even in poor weather, heavily traveled roadways and after long-term plowing and sanding.

The white markings use a tough polyurea binder that maintains its whiteness due to UV-stable technology that inhibits fading. On the other hand, the yellow markings are lead-free and incorporate durable yellow reflective elements that ensure the same vivid yellow color, day or night, and in wet or dry conditions. A combination of the polyurea and the reflective elements assures clear, 24-hour visibility, even in poor weather conditions, according to 3M officials.

Reflectivity testbed

The state of Illinois has been testing the 3M Liquid Pavement Marking System in districts statewide over the past four years.

Contractor Jerry Sladek of A.C. Pavement Striping has been involved in the testing process.

Sladek said, "after four years, the white has stayed white--almost as white as when we applied it. Not only is the reflectivity still holding, but the durability as well."

As a result of these tests, Illinois is now using the product extensively for interstate edge lines. Last year, the state applied millions of feet of the pavement marking with more specified for this year. The product will be used exclusively for edge lines on the largest reconstruction project in the state-the-art I-74 project in the Peoria area.

Another factor that contractors are particularly attracted to is the pavement marking's drying time.

"It dries fast--in 2 to 3 minutes--which means we can apply it in a short convoy without setting up cones in a work zone," said Sladek. "When we can open to traffic in two minutes, we prevent traffic jams, increasing safety for drivers and the workers."

Extending striping

In addition to the quick drying time, another advantage of the product is that it extends the striping season due to its wider application window.

Many pavement marking materials become increasingly difficult to work with as temperatures drop.

According to 3M, their Liquid Pavement Marking System can be applied in temperatures as low as 40°F, lengthening the pavement marking season by as much as three months in some climates.

The manufacturers claim that no other liquid system can be applied at that low temperature range. This enables many more construction projects to finish on time rather than waiting out another winter season.

The marking system can be applied via a mobile truck which allows for continuous and skip-line patterns to be marked simultaneously at application speeds in excess of five miles per hour. It can be used for long lines, edge lines, channelizing lines, gore markings, symbols, legends and crosswalks. It is suitable for application on both asphalt and portland cement concrete.

In the groove

A number of applications in northern and northeastern climates have been made in recessed surfaces. Workers use special grinders or groove cutters to create a slightly recessed groove in the pavement, applying the marking material in the grove. This process provides extra protection from snowplows, enhancing the longevity of the marking. Greater life expectancy and performance can offset the additional application costs.                                       TME