As the long winter tapers to its last few days and the snow turns to slush, many low-volume roads on farms and woodlots will face maintenance challenges.
Get a head start when thinking of building a new wood road by considering such details as the slope of the hills, surface stability and preexisting drainage around the road. Failure to deal with any one of these variables will cause the road to erode quickly and form potholes or washboards, which will cause unnecessary maintenance that costs plenty.
Managing water movement is a major concern with woodland roads. “Use of a filter fabric will benefit you greatly,” said Mike Smith, technical training specialist for the Baystate Roads Program at the University of Massachusetts.
There are many manufacturers and several styles, including woven, non-woven and filter fabrics. “They all provide a more stable surface,” Smith said.
One good rule of thumb is that a bad road in a good location is almost always better than a good road in a bad place. “Best Management Practices Field Guide” by US Forest Service engineers Gordon Keller, PE, and James Sherar, PE, stated that a bad road in a good place can always be fixed or upgraded as problems arise but changing the location of a good road because it was built in a bad location is expensive and time consuming. To make sure a new road will be in a good location, a common-sense tactic is to flag out several possible routes where the future road could go. Ranking the pros and cons of each route will help pick the most efficient, safe route.
Consider driving distance from multiple destinations on the farm, drainage sites, creek crossings and the overall terrain of each route. No road should cross a slope exceeding 60 percent. And no road should be perfectly flat since water will not be able to run off the road. To achieve the proper grade and runoff the road needs to be on high topography to avoid streams and hills. Having the route naturally dip down on the sides can be a plus because this will allow the water to trickle down and away from where vehicles drive.
Last, it is smart to test drive each route to determine if the soil will hold up and handle large vehicles.
Stream crossings are a huge engineering consideration. Although good practices, topography and route efficiency are all important in building low-volume roads, the single most detrimental factor to the road itself is water. Failure to plan proper water management – even for a low-volume road through the woods – will destroy the road and your wallet.
If an existing drainage system is not available, building a basic crossing is popular, but risky. These crossings can be good to get over large streams that have flood potential. If the structure collapses or water engulfs the crossing, consequences will be dire, ranging from road closure to farmland destroyed by debris flow. In most areas of the Northeast, maximum rainfall will be around 100 mm/hr (4 in/hr). This number can be used to estimate how high a crossing needs to be to minimize flood threat.
Putting in a traditional round pipe that is too small for maximum waterflow will change the stream’s velocity on the outlet side and cause ponding on the upstream side. Either situation will cause trouble.
“You have to look at putting in something 1.2 times larger than the high-water width of the stream so the culvert is not overtaken by water,” Smith said.
Smith noted that building a proper culvert is expensive. The alternative, however, is rebuilding the crossing several times over the life of the road. “Planning for a 100-year storm is painful up front but in the long run you will save money,” Smith said.
Several states, Massachusetts included, have mandated requirements to assure aquatic life can freely pass culverts. Called the Openness Test, it requires culverts meet additional design engineering criteria.
The simplest way to manage water flow on the road is to use the area’s natural geography. Crowned roads will help start the water management process. The road should not be close to any rivers, creeks and waterfalls running off from hills and mountains. If there are trouble spots along the road in which snow runoff is present, a drainage system can be placed to control the situation.
Simple local knowledge of the area can be used to determine if the quantity of runoff can be held in a small watershed, which is around 300 acres. A regression analysis and high water marks are common methods when the amount of runoff calls for a medium or small irrigation system.
Usually a large drainage system is only needed in the case of a 10,000-acre watershed, Keller and Sherar said.
On a low-volume road, dust probably will not be an issue. So Smith said crowning is not as important. “Instead,” he recommended, “look at the contour of the land. If it rains, water on a crowned road will flow in two directions. It is better to keep all the water on whichever side makes more sense.”
About every 150 feet a culvert should be placed to pick up water before it starts to flow too fast.
If the road is crowned, it should have a slope of a 1/4-inch per foot.
Where a woods road meets the county hardtop, be sure to stop crowning the gravel 150 feet before the transition to hardtop. Read the waterflow where the gravel meets the pavement. “If you have a swale, the gravel should come in lower,” Smith said.
Washboarding is caused by many factors. Chief among them are the speed of the grader and inadequate moisture control.
Look at the washboard pattern, Smith said. If it is straight left-to-right across the road, it is caused by a lack of dust control and vehicle traffic.
If it is angled or “loping” across the road, it is caused by running the grader too fast and the blade skipping. “It is a domino effect and you can’t stop it once it starts,” Smith said.
Choice of gravel is important in surfacing. Think bigger than 3/4 inch gravel. “Crushed is better than screened gravel,” Smith said.
Once a route for the road has been set there are a few “don’ts” while constructing it. Do not bury stumps or logs or anything similar in the road because, over time, this debris will surface and cause damage to the road and vehicles, Keller and Sherar warned.
Actual construction of a woods road in wet weather is not advised, since the water will soften the soil and change the road’s overall physical appearance.
If sufficient funds to build the road properly are not available, do not take shortcuts and, in the process, not meet all minimum road standards for safety and environmental protection.
If standards are not met, there will be repercussions. Repairs will be more expensive than the road’s original construction.
Curt Harler, who has a B.S. in agriculture from Penn State University and an M.S. in ag from Ohio State University, is a full-time freelance writer specializing in green topics.
Nate Roach is a freelance writer who lives in Steamboat Springs, Colorado. He specializes in green, sports and business writing.