Montana Department of Transportation

Frequently Used Terms

MDT Maintenance and Construction Activities

Chip Seal
The placement of a new riding surface that consists of an application of oil - the seal, followed by the placement of a layer of small rocks – the chips. May also be referred to as a seal and cover. Chip seals are usually short-duration projects. However, for at least the first 48 hours that a chip seal is open, traffic will be required to travel at no more than 20 mph. Chip seals may be done separately and are usually performed on all projects that involve paving.
Clearing and Grubbing
Includes removing and disposing of trees, stumps, brush, logs, limbs, sticks, piles of debris, vegetation and other matter within the right-of-way.
Embankment Work
Also referred to as earthwork, typically occurs on reconstruction projects.
Milling
A grinding operation that removes pavement to a specified depth. It's generally performed one lane at a time. Driving may be permitted on the milled surface depending on how strong the remaining surface is. Milling on an entire project can usually be accomplished in a week. A project that involves milling will typically include paving and chip seal work.
Paving/Overlay
These are essentially the same. An overlay is the placement of a new plant mix (asphalt surface on a roadway that is already paved. An overlay can be called paving because that is the actual operation but paving may also mean the placement of plant mix on a new base. The duration of a paving operation depends on the length of the project, the number of lanes, paving thickness, and hot plant output. Depending on its thickness, the new asphalt may be placed in more than one layer or lift, which will also increase the time a road is under construction.
Pulverizing
This operation involves breaking up the existing paved surface into small particles (2" or less). It is essentially a rototilling of the pavement. It may also include the addition of cement or base gravel. The pulverized surface must be paved.
Reconstruction
This involves rebuilding the entire roadway. It may involve changes in horizontal alignment (flattening or eliminating curves), vertical alignment (reducing grades, providing longer curves to increase drivers sight distance), modifying cut and fill slopes and widening the subgrade (the road base). It will always involve the placement of new base gravel and a new plant mix or concrete driving surface. It generally involves the replacement of all drainage structures, although existing bridges will be used in place if they are wide enough and are structurally sound. Reconstruction projects are the longest duration projects often extending into the next construction season. They also generally result in the longest driver delays.
Rut Filling
This involves the placement of a bituminous material in wheel ruts. It may be done with a paver or a motor grader (motor patrol).
Slope Flattening
his work involves flattening or grading of the slopes adjacent to the roadway. These areas may include the slopes between lanes on an interstate highway or slopes located outside of the shoulders on two-lane highways. It is done as a safety feature to help for better opportunity to recover should your vehicle leave the paved roadway surface.