Road Maintenance
Much of the information in this page has been adapted from the following source:
Handbook for Forest and Ranch Roads, June 1994, i.e., "The Green Book"
A Guide for planning, designing, constructing, reconstructing, maintaining and closing wild land roads
Prepared by William E. Weaver, Ph.D., and Danny K. Hagans from Pacific WAtershed Associates
These handbooks are available by sending checks payable to:
Mendocino County Resource Conservation District

405 S. Orchard Avenue

Ukiah, CA 956482

Introduction to road maintenance

Regular road maintenance is essential to protect the road and to prevent environmental damage. All roads used for vehicle travel should be regularly inspected and maintained. If adequate personnel and financial resources are not available to provide for regular, long term maintenance, roads should be built (or rebuilt) as temporary, and then properly abandoned or closed at the end of the planned operations. Temporary roads that have been properly abandoned do not need continued maintenance and pose little threat to downstream resources.

Inspection and maintenance schedules

Roads and drainage structures along all roads should be inspected annually, at a minimum, prior to the beginning of the rainy season. Inspections should cover culvert inlets and outlets on stream crossings, ditch relief culverts, and road surface drainage such as water bars, out sloping, and ditches.

In addition to annual, pre-winter road and drainage structure inspection, crews are needed to inspect and perform emergency maintenance during and following peak winter storms. Shovel work at a culvert inlet that is beginning to plug can save the expenditure of thousands of dollars to rebuild an entire stream crossing after it has washed-out.

Some drainage structures are more prone to problems than others. For example, culverts on streams with heavy sediment loads or floating woody debris may be more likely to plug. Landowners or land managers frequently know which culverts in their road system have had the most problems, and which are most likely to plug during a winter storm. In contrast, many culverts, ditches and road surfaces almost never have erosion problems, no matter how severe the winter storm.

Maintaining permanent roads

Road maintenance should address the road surface, cut banks, and fill slopes, as well as drainage structures and erosion control measures. A poorly maintained road surface will channel water, reduce road life and increase erosion and sediment pollution to streams. It may also be difficult or hazardous to drive on and damage vehicles and equipment.

The first rule of maintaining a stable road surface is to minimize hauling and grading during wet weather conditions, especially if the road is un surfaced. But even the best surface can be severely damaged by overuse during wet ground conditions. Be aware of early signs of road damage. Serious damage to road surfaces begins with loss of road drainage and excess water standing on the surface. Ruts indicate that road strength is deteriorating. Shutting down for several days can save thousands of dollars in road repairs and prevent unnecessary erosion and sedimentation.

Similarly, hauling on dry road bed in the summer can churn and pulverize road surface material and create thick, loose layers of soil and rock powder (dust). Loose materials can then erode and flow into streams with the first fall runoff. Summer hauling should be accompanied by dust control and watering to maintain the road surface condition.

Road surface should be graded only when needed to maintain a stable, smooth running surface and to retain the original surface drainage. Over-grading results in unnecessary erosion and increases road surface rock wear. Steep road sections will quickly loose their running surface with frequent grading, so raise the blade wherever grading is not needed! In addition, grading should only occur when the materials are slightly damp. Road surfaces graded when they are too dry will not compact and will result in subsequent erosion.

Grading should cut deeply into the road surface so loose material will mix, compact and bind with underlying materials. If deep potholes or ruts cannot be graded out, the surface should be ripped and then graded and re-compacted to achieve proper binding. Otherwise, individual holes and ruts that are patched will quickly re-form in the same locations. Oversized rock fragments that come to the surface during grading can be moved off the side of the road. However, unplanned berms that concentrate runoff during winter rains should not be left along the outside edge of the road.

Over years of hauling and grading, road surfacing materials gradually break downs or are inadvertently moved off the side of the road. Steep sections of road and curves experience the highest rates of wear. Often, larger rock fragments are left jutting out of the road bed while the fine materials have been washed or blown away. This makes for a rough ride, and can significantly increase hauling times. When this occurs, it is time for the road to be resurfaced or restored. The road bed should be ripped and new loads of properly graded rock aggregate spread, mixed and compacted into the existing materials. If past grading has piled good surfacing materials along the outside edge of the road, it can be retrieved and worked back into the road bed.

Where inside ditches are used, ditch maintenance is important in order to clear blockages and maintain the flow capacity required to remove surface runoff. Inspecting ditches during periods of high runoff will tell you which ditches need grading to improve their capacity, and which ditches are carrying too much water. Often, nothing more than shovel work at problem spots is required to solve ditch drainage problems. Additional ditch relief culverts can be installed to drain ditches that show signs of erosion or downcutting. Where sections of ditch cannot be drained, such as in a through cut, rock armoring should be installed.

Frequent, routine mechanical grading of ditches is usually unnecessary and can cause erosion of the ditch, undermine cut banks, and expose the toe of the cut slope to erosion. Ditches should be graded only when and where necessary. If cut bank slumps have blocked the ditch, clear out the material and move it to a stable storage site. Remove other sediment or restrictive brush and weeds from the ditch only if they create obvious drainage problems that affect the road surface. Do not remove more grass and weeds than is necessary to keep water moving. Vegetation prevents scour and filters out sediment. If the ditch is not a problem, don't "fix" it. Routine mechanical ditch grading should be avoided.

When "pulling" a ditch (mechanically grading and removing fine sediments), avoid pulling fine silts and clays across or into the surface rock of the road. This unfortunately common practice creates muddy surface conditions and potential for sediment pollution in streams during the next heavy rains. Large amounts of ditch spoil can be wind-rowed at the inside road shoulder for later end hauling by loader, backhoe and / or truck.

Stream crossing maintenance

Summer culvert inspections and maintenance is often performed at the same time as ditch maintenance. Culverts also need to be inspected and cleared during peak storms to prevent plugging. Problems found at such times should be corrected immediately, because delay can result in road damage requiring costly road repairs. The critical component of successful culvert maintenance is to fix problems before complete failure occurs.

Hand, shovel and chain saw work can take care of almost all culvert maintenance needs. Floatable debris should be removed from the catch basin and material wedged in the culvert inlet or hung up in the debris barrier should be removed and placed where it cannot get back into the watercourse. Sediment deposits that threaten to plug the culvert may need to be excavated. Culvert ends that have been bent or damaged during grading or by falling trees or branches should be straightened and re-opened. Outlets that are experiencing erosion should be armored or fitted with a downspout, and culverts that continue to experience overflow problems may need a larger pipe, or a second, overflow pipe installed at the crossing.

Bridges and fords may also require maintenance. Permanent fords that show erosion may need additional rock armor. However, except for emergency repairs, equipment should avoid operating in the flowing water of a ford, and re-armoring may have to wait until low flow conditions, or at least until peak flows subside.

In contrast, riprap and other bridge abutment protection should be repaired as soon as damage is noticed to prevent loss of bridge foundations and approaches. Floating trees and other debris that becomes lodged in the bridge structure should be cut free and removed or floated downstream. When cleaning bridge decks, soil and debris should be scraped to the adjacent road or hauled off. Material should not be dumped, scraped or washed into the stream. This is especially important during low flow conditions in the summer or the fall.

All road grading should take material away from the bridge, and loose spoil should be kept away from the stream. If the approaches are persistently muddy during wet conditions, and cause trucks to bring dirt onto the bridge decking, then the approach should be rock surfaced or paved.

Maintaining cuts and fills

The key to maintaining cut and fill slopes, including side cast materials, is to observe and note when and how changes to these features occur. Corrective measures can then be implemented, depending on the problem.

Typical cut slope include excessive raveling, rilling, and slumping which may block the ditch or require frequent ditch cleaning and maintenance. In the long term, it may be necessary to flatten the cut slope, re-vegetate bare soil areas, widen the ditch (so that it does not plug so easily), install ravel barriers on the slope and at the base, and/or build a retaining structure to contain or prevent slope movement. Often, simply loading the toe of a small cut bank slump with heavy riprap can provide sufficient weight to stabilize the feature. Stabilizing or controlling the movement of larger unstable areas may require analysis by an engineer or engineering geologist.

Instability in fill slopes and side cast materials often shows up on the surface or edge of the road. The outside perimeter of landings built using side cast methods commonly show such developing instabilities. Some settling of newly placed side cast can be expected, but if movement persists and scarps continue to develop, the unstable materials should be excavated and removed, including organic debris, before they fail. If the potential instability is perched above a stream channel immediate treatment is usually required.

Regular inspection and prevention (including excavation) is the key to maintaining stable fillslopes and sidecast areas. Local slides and slumps in the road bed often occur where material was placed or pushed over groundwater springs or seeps, where the road crosses steep swales, or where rotting roots, stumps or organic debris have been buried. These areas should be closely monitored and require fast action if cracks or scarps develop. Improved drainage (e.g., extra ditches), excavation of unsuitable soils or buried materials, or retaining walls may be needed. Left untreated, these unstable features can fail suddenly and develop into debris flows and landslides that deliver large amounts of sediment directly to down slope stream channels.

Winterizing Roads

Before winter, all permanent, seasonal and temporary roads should be inspected and prepared for the coming rains. Winterizing consists of maintenance and erosion control work needed to drain the road surface, to ensure free flowing ditches and drains, and to open all culverts tot heir maximum capacity.

On un-surfaced roads, water bars, wattles, and temporary sediment catch basins may be required at spacings dictated by the road gradient and the erodibility of the soil. Trash barriers, culvert inlet basins and pipe inlets should all be cleaned of floatable debris and sediment accumulations. Culvert outlets might need to be enhanced with energy dissipaters in order to minimize erosion. Ditches that are partially or entirely plugged with soil and debris should be cleaned and heavy concentrations of vegetation which impede ditch flow should be trimmed. Loose debris on the road should be stored locally or hauled away. This is also the best time to excavate all unstable or potentially unstable fills and sidecast which could fail and be delivered to a watercourse during the coming winter.

Spoil disposal

If excavations, grading and culvert basin cleaning and maintenance produces excess material, it should be stored locally or hauled away. Spoil may be feathered over the road, but on permanent roads, excess fine material may produce unwanted muddy conditions after the first rain. Spoil material should be hauled to a stable site safely distant from streams, contoured to disperse runoff and stabilized with mulch and vegetation. Excess spoil from maintenance activities should never be sidecast near streams.

Coast Property Owners Association, P.O. Box 59, Big Sur, CA 93920
© 2004 by Coast Property Owners Association