How to build a road ramp?
I'm in Ghana and working with WSUP. One of the tasks I have is to cut a road to our site. It's not huge, only about 100m long and goes over a 1.8m drop.
I'm fine with most of it but was wondering if you knew anybody that could advise me on building a decent ramp. It'll have to be good enough to take 10T vacuum tankers of sludge and the initial HGVs needed for site construction.
Thanks for any help
The gradient of the ramp should ideally be around 1:15 for ease of construction and safety. The steeper it is, the harder it will be to construct.
Not sure what type of fill material for the ramp is available locally but whether granular or cohesive material, it is important to thoroughly compact to refusal each layer preferably with a mechanical roller. Each compacted layer in the ramp should ideally be around 250mm.
The surface layer of the ramp should be finished with a stiffer material like asphalt or concrete. A thickness of about 100mm for asphalt or concrete will provide a good running surface and will last longer. If asphalt or concrete is not feasible then the top layer of about 250mm should be placed with a finely graded material to help seal the surface as much as possible. Also, if this top layer material could be mixed with some cement to produce a dry lean concrete mix and compacted as above then it will provide a more robust surface. If the ramp is finished with only unbound materials then it will be subject to increased deterioration and will need regular maintenance as the ramp will be a highly stressed area with slow moving trucks braking and accelerating.
A ramp suitable to overcome the 1.8m drop in level is illustrated on the accompanying diagram.
The important features are:
A gradient of 1 : 10 for the ramp should be suitable for most large vehicles. Powerful vehicles can manage 1 : 8 or even 1 : 6 slopes but for general and safe use 1 : 10 is recommended (i.e. 18m long for 1.8m height). Ramp side slopes of 1 : 2 are recommended to ensure stability of the sides and resistance to erosion.
Granular fill (sandy, stony or rocky material) should be used and should be compacted while being built up to height. Clayey material should be avoided as it cannot be compacted properly and becomes soft when wet. The side slopes can be protected from erosion due to heavy rain by covering with coarser stones and rocks.
Hope this is useful. Please ask if unclear or insufficient.
Giles Waley (Civil Engineer)
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