Seal Coat

Seal Coating Adds Life to Missouri Roads, Saves Taxpayer Dollars

Seal coating is a process whereby a hot emulsion oil (150 degrees F) is sprayed onto the surface of the road, followed by placing finely ground rocks on top. The rocks are then compacted to make them adhere to the roadway. Finally, any excess materials are swept from the surface, leaving an improved roadway that will hold up longer than it would have without the treatment.

Seal coating a road is about one-third the cost of a conventional asphalt overlay, averaging $18,000 per mile as compared to an estimated $56,000 per mile for an asphalt overlay. The seal coat keeps damaging water from penetrating paved surfaces and extends the life of the pavement for an additional five to seven years. The process also seals cracks and improves roadway traction.

A surface may be seal coated several times, providing the road remains structurally sound. The process is typically used on roads carrying lower traffic volumes which make up more than half of MoDOT’s roadway network.

Cost Comparison
Seal Coat
Asphalt Overlay
Dollars Per Mile

Motorist Safety

Motorists need to observe the speed limit of 35 mph on roads where seal coating is in progress.

Motorists should also be aware that flaggers and pilot vehicles are frequently present at seal coat operations and vehicles may be required to come to a complete stop. Traffic delays are possible, so travelers should consider alternate routes, if available.

Road condition information is available 24/7 on MoDOT’s Traveler Information Map located at or through MoDOT’s smartphone app which can be downloaded free for iPhone and Android phones.