ATTACH_14-_Appendix_A_Road_Maintenance_Technique_Definitions_.docx

Road Maintenance Technique Definitions General:

The following definitions and discussion of road maintenance terms are taken from “Environmentally Sensitive Maintenance for Dirt and Gravel Roads”, by John A. Anderson, Ph.D., and Allan L. Gesford, P.E., & the Penn State Center for Study of Dirt & Gravel Roads (http://www.epa.gov/owow/nps/sensitive/sensitive.html ) . These definitions are to be used for road maintenance requirements discussed in the Statement of Work and the Sample Work Plan for Work Area #4.

Basic Techniques: First, no matter what work is being done on the road, it should be planned when there is adequate moisture. This usually means that all work should be done after a rainfall unless there is an available water truck and water source. Adequate moisture is needed not only to achieve proper compaction for structural integrity and strength, but also to avoid dust.

Dirt and gravel roads are usually maintained through three basic practices: blading or smoothing, reshaping or regrading, and adding new material. Gravel road deterioration, like any paved road, will develop in stages. Low severity surface distresses such as roughness, loose gravel, and minor ripples appear first. Blading or smoothing the road surface frequently to correct these distresses will result in less intense efforts of reshaping or adding new material. When the road loses crown and more severe distresses appear, a reshaping or regrading to re-establish proper crown is required. The more frequently we reshape using existing road material, the less often we will need to add new material. Sooner or later, however, the road loses crown and enough material has been lost off the roadside or by way of erosion and dust that there is not enough remaining material to simply regrade the road. Then we must add new material in order to re-establish the crown and have an effective road profile.

Blading (or Smoothing):

As described above, blading a road is needed when surface distresses appear but the road still has a good crown. We need to blade the road to smooth the rough surface to restore good rideability and prevent further more extensive distress. When using the motorgrader, the moldboard angle and pitch is critical to doing good maintenance. The moldboard should be angled somewhere between 30 and 45 degrees, tilted forward, with light down pressure. A 10 to 15 degree tilt on the front wheels will help oppose the resisting forces and stabilize the operations. A speed of 3 to 5 miles per hour is considered average, but there are many conditions or variables that may require slower speeds for effective operations. With the blading or reshaping operations, compaction of the material is often left to traffic.

Regrading (or Reshaping) As stated above, when the road loses crown and more severe distresses appear, a reshaping or regrading to re-establish proper crown is required. With the moldboard tilted slightly backward and sufficient down pressure to produce a cutting action, the road is reshaped to restore proper crown and cross-slope for good drainage. A minimum of four passes may be required, with a first pass in each direction to cut and windrow the material to the road center and then a second pass in each direction to spread the material back across each lane. The cutting action should be deep enough to cut to the bottom of all existing distresses such as corrugations, ruts, and potholes or soft spots.

Since this operation is being performed to restore proper crown and cross slope, check the resulting cross slope to insure it meets the half inch to three quarters inch drop from the center of the road with the flat “A” shape. This operation should include a compaction effort. Using rollers for proper compaction of the disturbed material will result in a stronger road for a longer period of time.

Adding New Material (or Resheeting): If there is not sufficient material remaining to regrade and restore proper crown and cross slope at the proper elevation, additional road material will have to be added. Prior to adding new material, the road should be in good shape with all other maintenance work performed. All distresses, such as corrugations and rutting, should be repaired and the road brought into the proper condition and shape to receive the new material. If the existing road surface is smooth or has a hard crust, the surface should be lightly scarified to loosen surface material to provide a good bond between the road surface and layer of new material. Compaction is again required to provide the proper density for structural strength and durability.