For the kind of soil we have in Nigeria, it varies from very clayey to sandy materials. Depending on where you are the subgrade below the asphalt must be very stable and consolidated. The depth must also be deep to withstand the continuos weight being introduced constantly by vehicles. In Nigeria not only do we have problems with these subgrades as it is designed for diffrent loads from single cars to traikers. The inability of the road users to diffrenciate one road to other makes a trailer to travell over roads designed for cars only. Or those trucks picking up trunk tress to the saw mill do not know which road to travel. The government also do not make it a point to designate the roads also and that makes it very difficult. The subgrade could also be affected by drainage patterns, we are used to open drainage system and when it rains, the drainage pattern kind of stand uneven which causes water to stand continuously in diffrent spots thereby creating stress points which later develops to potholes. The lack of proffessional inspectors with duities to make sure all materials are verified and within the specification is lacking. Thi is just a few pointers out of many. All these area mentioned above is where the contractor steals money as no checks and balances. It is the areas where low materials or inferior material or no materials are used. Untill watch dogs or qualified personnel are used to monitor these contractors and these contractor are held to the designed graterial they sign, we are not going anywhere. For your info, the runway at the Hartfield international airport and the tsa area in Atlanta were my project when i was there.i was the chief inspector, and other projects in usa.30years in that field!!
Posted on: Fri, 22 Aug 2014 12:41:02 +0000
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