Gravel roads are the largest infrastructure investment for townships—and maintaining them is a high budget priority and burden. Since these roadways are where most agricultural products begin their journey on the transportation network, properly constructed and maintained gravel roads can make shipping more efficient and promote economic activity.
Gravel surfacing is the most common roadway improvement for township roads—and one that requires the most maintenance. Aside from regular maintenance, good gravel roads also require proper roadway geometry and quality material. Sacrificing any of these qualities may result in longer-term maintenance requirements—and costs.
Roadway geometry, or the design and layout of a road, includes horizontal and vertical alignment, sight distance, and other aspects contributing to safety and efficiency. Gravel roads, in particular, are defined by three design elements: a crowned driving surface, a shoulder that slopes away from the driving surface, and a ditch to convey water. The crowned driving surface should slope away from the center of the road at a specified grade, usually a one-half inch drop per foot of width. The shoulder should create an additional slope to carry water to the ditch, and the ditch should collect water and keep it from pooling on the roadway surface. Fixing existing roadways to meet this standard is expensive, but generally proves more cost effective over time.
To keep a gravel road in good shape, owners will need to invest in quality material for the build. The Minnesota Department of Transportation (MnDOT) has created two specifications for gravel surfacing (Class 1 and Class 2) that any licensed contractor or local supplier can provide. Since gravel is often mined and mixed for each job, owners should also verify the quality of the material purchased with testing provided by a third party to ensure that it meets standards.
Regular, recurring maintenance will keep the road in proper condition. This requires trained staff (or contractors) and equipment to preserve the road geometry and provide additional gravel when necessary. Maintenance can also include restoring the crown or cleaning ditches—in other words, it’s the best way to find and fix problem areas. Maintenance should be completed following best practices outlined by the Federal Highway Administration (FHWA), with timing dictated by staff availability and roadway traffic.
Many resources are available for additional education, including MnLTAP, which offers gravel road courses for all township staff and officials. MnLTAP also provides motor grader operator training, available to all local agencies, and training for elected officials on roadways and legal weight limits through its Truck-Weight Education Program. Additionally, FHWA and MnDOT have published gravel road guidebooks that can be accessed online.
—Andrew Wrucke, MnLTAP director