Pay attention to slope percentage on logging roads

The key to a strong well drained road is a properly sloped crown. That’s the word from Glen Légère, Associate Program Leader of Resource Roads for FP Innovations FERIC division. While the importance of the crown in road building is well known to most in the business Légère says there is often not enough attention paid to creating the correct percentage slope. This is one of the reasons why FERIC recently produced a step by step flash presentation focusing on road drainage best practices for road supervisors and operators.

"Typically what we are aiming for in a well drained road is a good crown. We normally focus on a 4 to 6% slope," Légère said. "With a slope of 4% the water will drain off the road properly toward the ditches and it will keep the road in better condition. It will reduce the creation of potholes and standing water and any failures in the road structure."

"Most companies know that a crown is important and they all try to get one on the road but many are below the four percent slope that is what we are trying to reinforce, and why we felt the need to develop that product and promote the role of proper drainage." Légère said. "It’s all a matter of knowledge transfer and training the operators to keep the crown at an adequate slope. We don’t always see a four percent we often see flatter roads or bowl shaped roads where water can accumulate in the centre."

Another key component drainage is adequate ditching that can support the volumes of water shed by the crown and which can carry that water away from the road. When it comes to curves, Légère says that the crown must be abandoned in favour of what is called a super elevation where the road is banked from one side to another. A super elevation gives vehicles added stability on the curve while maintaining good drainage.

"You may also see in the winter time, companies flattening the road a bit more," Légère said. "On main haul roads companies will prep the road as they get into the late fall because a flattened crown will give better vehicle stability in icy conditions and they don’t have to worry as much about damage or drainage."

Légère stresses routine maintenance as a means of maintaining good drainage throughout the year.

"Over time and with traffic the crown can be flattened out or reduced. One of the reasons for that is if the road is not wide enough the vehicles will tend to drive down the center of the road, or instead of four tracks you will have three tracks and that has flattening effect," Légère said. When you do your routine maintenance and reshape the road at the beginning of the year and in the summer you should be able to keep it at a decent crown."

In addition to their flash presentation, last summer FERIC ran a road drainage course. "Over the course of the year we developed a course for grader operators and delivered six courses across Ontario last summer and fall. We really stressed the importance of a proper crown and we also get into proper grading techniques in how to achieve measure and maintain that crown," Légère said. "We have done a lot of knowledge transfer and training on that over the year and flash presentation is sort of a useful tool that contractors can use and look at and show their operators. It can be used by road supervisors, road construction crews as general knowledge that is important to everyone."

In the future Légère says that FERIC hopes to continue the series of road building flash presentations to compliment the road drainage best practices.

"We have another presentation on culvert installation that we did a few years ago and we could have one on erosion and sediment control, constructions techniques, proper aggregates and gravel pit management. There is a whole series of topics we could cover," Légère said. ◊