 Gravel roads are designed for heavier traffic than earth roads. With proper maintenance, they will also last longer. Even with frequent smoothing and reshaping, the effects of weather and traffic will eventually erode the wearing course of compacted granular material. If the wearing course is not restored, the subgrade will become damaged, requiring the road to be rebuilt. This videotape will focus on adding new gravel to restore the wearing course. This operation is called regravelling. Regravelling is a major operation which involves many workers and pieces of equipment. It is essential to have good planning and coordination with your maintenance engineer. Schedule regravelling during good weather. Too much rain will delay the operation. Before regravelling, repair soft spots, deep holes and large depressions. For further repair information, refer to the IRF videotape Hatching Unpaved Roads. Clean all ditches and culverts before regravelling. Good drainage is essential for a long-lasting repair. The IRF videotapes on cleaning ditches and culverts will provide additional information. Before the work starts, determine the amount of gravel needed and its supply source for this operation. Also, determine if a detour is practical or if one half of the road must be regrabbled at a time. A detour will direct traffic away from the work site, making this operation more efficient and safer. You will need the proper equipment to do this operation. A motor grader to prepare the subgrade and spread the granular material. A rubber-tired roller to compact the subgrade and the granular material. Or you can use a vibratory roller. A bulldozer to stockpile the granular material. A front-end loader to put the granular material in the dump trucks. A sufficient number of dump trucks to carry the needed granular material to the work site. A water truck to be used for dust control and to maintain proper moisture of the granular material. A camber board to check the cross-slope. And rakes, shovels and a wheelbarrow to work the materials and remove large rocks and clay lumps. In addition to the proper equipment, you will need granular material which has been approved by the maintenance engineer. This material includes the correct proportion of coarse and fine particles which are well mixed. It can be provided from natural sources or from processing plants. Also, you will need an adequate amount of clean water for good compaction. The water supply should be as close as possible to the work site. To keep the number of needed water trucks to a minimum. Before we cover each step in detail, we will quickly introduce the six basic steps for regravelling. Step one, place the traffic control devices. Step two, reshape and compact the subgrade. Step three, load, haul and place the granular material. Step four, spread the granular material. Step five, compact the granular material. Step six, remove the traffic control devices. We will cover each step in detail. Step one, place the traffic control devices. Follow correct procedures for proper placement of signs, cones and barricades. They are important for everyone's safety. If this repair reduces two lanes of traffic traveling in opposite directions to one open lane, you will need flagmen to direct traffic. Refer to the IRF videotape on traffic control for further instructions. Step two, reshape and compact the subgrade. If regravelling must be done during dry weather, spray just enough water on the road to dampen its surface. However, the best time to reshape the subgrade is immediately after a rain. The damp surface will be softer for blading and will prevent the loss of fine particles. To reshape the subgrade, start from the outside edge. Work in passes about 200 meters long. If the surface is very hard, use the scarifier to break it up. Be sure to remove large rocks and clay lumps. Set the blade to cut to the bottom of the surface irregularity. The bottom edge of the blade must be in front of the top edge. To obtain the proper cross slope, which is generally 4%, position the blade so the end near the center line is slightly higher than the other end. Next, angle the blade between 30 and 45 degrees to the motor grader's axle to form the windrow toward the center line of the road. Now, shift the blade to place the windrow inside or outside of the wheels. Lean the wheels in the direction of the windrow to be formed to help counter side thrust on the blade. Make a windrow. Do not run the motor grader's wheels over the windrow. Next, spread the windrow. Set the blade forward at the top. Angle the blade to pick up and spread the windrow from the center toward the edge of the road. Adjust the position of the blade parallel to the cross slope. Spread the windrow evenly to form the proper cross slope. Continue reshaping the subgrade on the other half of the road. To check the cross slope, use a camber board. The camber board measures the fall of the road surface from the center line to the edge. This is called the cross slope of the road. The camber board must have the same cross slope that you want for your road. For a 4% cross slope, the road surface from the center line to the edge must drop 4 centimeters for each meter. To check the cross slope on a straight section of road, place the camber board straight across the road with its shorter end toward the center line and check the bubble. If the cross slope is correct, the bubble should be centered in the camber board indicator. Repeat this check approximately every 30 meters. The proper crown should look like this. On a curved section of road, the cross slope should remain the same across the entire width of the road surface. No crown should be evident, and the cross slope should look like this. Make the transitions between the curved and straight sections of the road gradually to look like this. If the bubble is not centered, the cross slope is too steep or too flat. To correct the cross slope, blade and spread the material again. The proper cross slope is very important for good drainage. When you have obtained the proper cross slope and before you compact the subgrade, use the water truck to add moisture if the subgrade becomes too dry. Compact the material with a rubber-tired roller by starting at the edge of the road, then overlapping each pass one-third the width of the roller as you move toward the center. Make several complete passes across the subgrade surface to fully compact it. This is necessary to support the new wearing course. Do not destroy the crown by making a pass down the center line of the road. Step 3. Load, haul and place the granular material. Use a bulldozer to keep the granular material in a shaped pile. The front-end loaders cannot work effectively with a hard bank or a low pile of material. Organize the loading operation so the dump trucks can be loaded quickly. After the trucks are loaded, haul the granular material to the worksite to be distributed over the compacted subgrade. To dump the granular material, start at the far end of the worksite so that the piles of gravel do not obstruct the following dump trucks delivering later loads. Space the piles according to the thickness desired for the wearing course. Dump the granular material in low piles near the edge of the road. Step 4. Spread the granular material. Start when there is at least 200 meters of dumped material. Set the blade to spread the material across the subgrade in an even layer. Several passes may be necessary to blend and spread the granular material evenly. Between passes, add water until the moisture content is correct for compaction. To quickly test the moisture content of the granular material at the worksite, squeeze a sample in your hand. If it crumbles, it is too dry. Water must then be added to increase the moisture content. If the sample remains in a ball after you squeeze, the granular material has the proper moisture. This will help obtain good compaction. If the sample runs out between your fingers when you squeeze, it is too wet. It must be allowed to dry before compaction. After the granular material is spread, check the thickness in several places using a sharp stick or steel bar. The thickness should be uniform. Also before you compact, check the cross slope the same way you check the cross slope of the subgrade. Step 5. Compact the granular material. Use the same procedure as for compacting subgrade. Remember to start on the edge, move toward the center, and do not make a pass down the center line. If the material becomes too dry during compaction, add more water to obtain the correct moisture. Make 8 to 10 complete passes to fully compact the granular material and to establish a smooth wearing course. Step 6. Remove the traffic control devices. Make sure heavy equipment and personnel are off the road before removing the devices. Pick them up in the reverse order of their placement. A regravelled road has a smoother riding surface and will last longer. To review this operation, there are six steps for regravelling. Step 1. Place the traffic control devices. Follow approved procedures to make the work site safe while regravelling is being performed. Step 2. Reshape and compact the subgrade. The correct cross slope must be established for proper drainage. Step 3. Load, haul, and place the granular material. Start placing the material at the far end of the work site and space the piles to help obtain the desired thickness. Step 4. Spread the granular material. It must be spread in an even layer across the subgrade. Step 5. Compact the granular material. Roll it until the wearing course is fully compacted and smooth. Step 6. Remove the traffic control devices. Pick them up in the reverse order as they were placed. Because of the many pieces of equipment needed for this operation, good planning and supervision are required. Close supervision of workers and equipment at all times is necessary to maintain safety at the work site. The objective is to produce a new wearing course that will support heavy traffic and remain smooth for many years to come. This objective will be achieved if all six steps are performed correctly. Thank you for watching.