 Drainage is one of the biggest concerns in highway construction and in highway maintenance. In the design phase, engineers have to carefully plan how to channel water away from the road. And in maintenance, it's our job to keep water away from the road. Because when moisture gets under the pavement, we can expect anything from potholes to base failures. One of the best ways to prevent these problems is to follow the procedures outlined in the maintenance handbook under edge rough repair and great gravel shoulders. Depending on the condition of the shoulder, this activity can require as many as 10 steps. But before we go too far, let's look first at a properly constructed shoulder. Basically, there are two things that have the greatest effect on drainage, the slope and the inside edge of the shoulder. The slope should be gradual and away from the road. In fact, the handbook says this, the slope should not be less than three-quarters of an inch per foot nor more than an inch and a half per foot, depending on the texture of the surface and the roadway grade. Now all that means is that on the average, the shoulder should slope away from the road about an inch per foot. So if the shoulder is about eight feet wide, the outside edge should be about eight inches lower than the pavement. As for the inside edge, there's one requirement. It should be flush with the road. That way the shoulder can drain water away from the road. If the edge is rotted, water will get under the shoulder and the road. And if there's a buildup of dirt or grass, the water gets trapped on the surface and can seep in through hairline cracks. Either way, there's going to be problems. So again, shoulders have to have a gradual slope of about an inch per foot and the inside edge of the shoulder has to be flush with the pavement. Okay, now that you know the requirements, let's look at the procedures for edge rut repair. The first thing to do is to set up all the required traffic control signs. At a minimum, you'll need roadwork ahead signs on each end of the work area. But flagries should be added if traffic warrants it. While the signs are being set up, the truck can be loaded. If you have a divider device for your truck, use it. If not, place a barrel in the truck. That's because on this job, the material has to be spread in a narrow path. So by placing the barrel along the tailgate on the passenger side, you can spread the material right where it has to go at the edge of the shoulder. But spreading is not the next step. Although edge rutting almost always requires adding material, the shoulder has to be pulled first. Pulling the shoulder serves one major purpose, to make the surface smooth and uniform. That way, when you spread the new material, you can spread it evenly. On the first pass, you want to pull material from the outside edge of the shoulder and windrow it up to the edge of the road. That requires a fairly sharp blade angle, about 45 degrees, with the toe of the blade set on the outside edge of the shoulder and the heel set near the edge of the pavement. Be careful not to make the shoulder any wider. Vegetation along the outside edge helps prevent erosion. This operator is just slightly clipping the edge to give the shoulder a neater appearance. The idea on the first pass is to maintain the original slope of the shoulder while cutting into the surface just enough to eliminate ruts and bumps. Slight downward pressure is usually enough. Here's what it should look like after the first pass. A smooth surface with a windrow at the edge of the pavement. Now, before you spread the material back across the shoulder, it's a good idea to drive along the edge of the pavement. The more you can compact each lift of material, the stronger the shoulder will be. Now for the next pass. You have to pick up the windrow and spread it back across the shoulder. Be careful not to damage the road. Lower the moldboard until it barely makes contact with the road and keep the heel loose so you don't form a windrow. Notice that the rear wheels follow right along the edge. Again, you want to compact each lift of material as you place it. As you can see, the shoulder is still lower than the pavement. So here, as in most cases, more material has to be added to bring the shoulder flush with the pavement. The spreading operation is pretty much the same for this job as it is for any other job. You have to raise the dump box and drive ahead before you release the tailgate lever. But there is one difference. As you can see, the material comes out more slowly near the end of the pass because of the barrel blocking one side. So keep your eye in the rear view mirror and slow the truck to keep the spread uniform. This is what it should look like when you're done. A narrow windrow of material placed at the edge of the road. The next step, of course, is to spread the material back across the shoulder. Here again, the wheels should follow along the edge to compact the material as you spread it. And because each previous lift of material was compacted, the shoulder should be almost flush with the pavement at this point. After the material has been spread, it has to be compacted for the full width of the shoulder. And you should always start at the low side and work toward the road. That way you push the material where it's needed the most at the edge. When you're through, this is what it should look like. A firmly compacted shoulder with the inside edge flush against the pavement. And that's the procedure for edge rut repair. To review, set up whatever traffic control devices you need to do the job safely. Pull the shoulder while maintaining the original grade and slope. Pack the material at the edge. Spread the material back across the shoulder, compacting it as you go. Place new material in a narrow windrow along the edge of the shoulder. Spread it across the shoulder, again compacting it as you go. Compact the entire shoulder, starting at the low side and moving toward the edge of the pavement. Now let's look at the procedure for grading gravel shoulders. The procedure here is pretty much the same as it is for edge rut repair. The main difference is the severity of the problem. As you can see, the edge rutting here is not nearly as extensive as it was in the last example. So now is the perfect time to repair the shoulder before water has a chance to get under the pavement. And because the damage is minor, many of the steps can be eliminated. In fact, all you have to do is pull the shoulder, then spread the material back across it. But be careful to place the windrow right at the edge of the pavement. That way, when you spread material back across the shoulder, the wheels can follow right at the edge so you can compact the material as you go. Remember, firmly compacting the material is one of the most critical elements of repairing the shoulder. And that brings us to the end of the program. As I said in the beginning, maintaining proper drainage can give our roads a longer and more useful life.