bridge

Resource specialists show the Managed Forest Council around a bridge on private forest land.

Welcome to the fifth post in our “Planning Your Road Network” series. Last month’s post revealed the secret to a good roadbed is keeping it well drained. The post also highlighted the importance of culverts in achieving that goal.

Culverts aren’t your only consideration. Bridges, swords, bales and ballasting are other construction considerations you’ll need to think about when you’re building your road network.

Bridges

Bridges are recommended when stream flows require steel culverts with diameters above 120 cm, or log deck culverts with a span of over 3 metres. At this point, call in the experts. The cost of seeking professional advice is worth it.

Fords and Swales

If your road crosses a shallow low-flow stream, or seasonally wet area, with no down stream fish or water source values, an alternative to a culvert is a properly constructed ford or swale.

Remove any silts and fine soils on the approaches or in the ford/swale. Stabilize the approaches with uphill waterbars. Lay down geotextiles to strengthen the roadbed. The bottom of the ford/swale must be firmly ballasted with coarse rock. Shot-rock works best because it leaves channels for water flow. The purpose of a ford is to provide a safe, erosion-free and storm proof crossing that requires little or no maintenance.

Ballasting

Forest roads require ballasting to provide for all-weather hauling. The costs of ballasting are high due to the amount of equipment involved—usually a hoe or loader, a truck to haul the gravel and another hoe or small bulldozer for spreading the material.

These costs rise rapidly with the distance of the gravel source from the road. Where traffic is light and seasonal, packed dirt roadways, with only the trouble spots gravelled, may suffice.

For final shaping of the road profile, nothing matches the production and quality of a road grader. Inquire at your local Ministry of Transportation and Highways to see if they or their contractor may have a machine in your area. It is often possible to coordinate activities and obtain a very reasonable rate.

We’ve covered a lot of ground (pun intended) in the past five posts. Here’s a quick list to help summarize the steps to follow when you’re building your road network:

  1. Develop road plan for woodland area
  2. Determine road specifications for each management area
  3. For major, long-term roads seek help
  4. Lay out roads on maps and aerial photos, then locate roads on the ground
  5. Clear right-of-way
  6. Build the sub-grade (the basic road bed shape)
  7. Install drainage structures
  8. Ballast the road where necessary

As always, thanks to A Non-forester’s Guide to Small-scale forestry in British Columbia for the information excerpted above.

Please stay tuned for the final post in the series where we outline some tips for maintaining your road network. If you can’t wait, you can find the complete resource online here.