For South African game lodges, private nature reserves and farms with guest accommodation, it pays to ensure that unpaved roads are properly constructed.
Effective road construction for lodges and nature reserves translates to better road quality and durability, and lower overall maintenance costs. At the same time, it’s important to protect sensitive natural resources and landscapes.
Tips for unpaved road construction
Smooth, drivable gravel roads are achievable in any environment. The trick is to properly prepare the road’s foundation, use quality materials and supervise operations from start to finish.
When roads are constructed according to recommended specifications, maintenance is limited to blading and drain clearance.
Below we offer five gravel road construction tips for rough conditions.
Use locally sourced and properly processed material
The use of material available on, or close to, the road site saves time and reduces costs. When the gravel needs to be refined in any way, it is processed at the source. That way, the construction site is free of debris that may be bladed onto the finished road during routine maintenance.
Crushed material, smaller than 37.5 mm in diameter, is recommended for roads carrying 50 or more vehicles per day.
A “Grizzly”, portable crusher or rock buster is an effective tool for reducing bulky material to size.
Construct a strong foundation
The construction of the subgrade is key to an optimal roadway. Without a strong foundation, the surface is likely to deteriorate and degrade.
To achieve the required results, subgrade material is laid on a compacted and debris-free roadbed. Once the subgrade is formed and smoothed, the camber or cross-slope is shaped to 2% to facilitate outfall drainage.
Create an effective drainage system
The drainage system is an essential element of gravel road construction. It works in tandem with the formed slope of the road to remove water from the surface.
Flat-bottomed side drains are constructed parallel to the road. They’re wide and deep enough to deal with the expected flow.
The water captured in the side drains is directed well away from the road via mitre drains, which are between one and 1.5 metres wide.
They should be constructed at intervals based on the grade of the road. The steeper the grade, the greater the number of mitre drains required.
Build the road formation to recommended specs
To prevent the road from flooding, the surface is raised to a height of at least 300 mm above ground level. Material excavated to create the drainage system can be used to supplement new aggregate.
When building the road formation, a plasticity index of four is recommended.
The plasticity index represents the amount of moisture-laden clay present in the aggregate, which is compacted to 90% of its maximum dry density.
Processed aggregate moistened at source is easier to haul and compact.
Practice good surface course construction techniques
The surface aggregate is always of uniform thickness. This is achieved by dumping the gravel at intervals that allow for consistent spreading and compacting.
Moist compaction is most effective. There is less dust, and the compacted aggregate is smoother and less likely to degrade.
Hauling, dumping, spreading and compacting is best achieved in the wet season or early in the day, when there’s still adequate moisture in the material.
The services of a skilled grader operator guarantee a well-finished roadway that is smooth, easy to maintain and features an adequate drainage system.
A defined crown and cross-fall of 4 to 5% is the optimal shape and slope of the driving surface.
Finished roads can be treated with stabilisers or emulsions to reduce surface degradation, dust emissions and routine maintenance – leaving guests more comfortable and the property better-off.
For more information, see our unpaved road maintenance tips for lodges and nature reserves.
Affordable motor graders for road construction and maintenance
Does your property require a gravel road network? Is the existing road infrastructure due for an upgrade or regular maintenance?
Road construction for lodges and nature reserves depends on reliable motor graders.
Graders are vital for both building and maintaining gravel or dirt roads – and they’re engineered to perform multiple jobs. Among these are clearing debris, grading and sloping surfaces, and building culverts and drainage ditches.
KH Plant specialises in refurbishing Caterpillar 140G, 140K and 140H motor graders to as new condition. This means you can get the benefits of a new grader at a fraction of the new price. Contact us for more information or to discuss your needs.
