Materials that are commonly used to built our Roads.
- Rock (scoria)
- And various type of soils
All Roads should be compacted and test during construction, using heavy machine (vibrating roller with plain drum)
The construction plant available to achieve compaction is extremely varied and is described.A compaction test is a soil quality test used to assess the level of compaction which can occur in the soil on a site. Compaction tests are commonly performed as part of a geotechnical profile of a building site. They may also be performed to learn more about a soil in a particular area, whether or not the area is slated for development. A geotechnical engineer, geologist, or soil scientist may conduct a compaction test.A nuclear density gauge is a tool used in civil construction and the petroleum industry, as well as for mining and archaeology purposes. It consists of a radiation source that emits a directed beam of particles and a sensor that counts the received particles that are either reflected by the test material or pass through it. By calculating the percentage of particles that return to the sensor, the gauge can be calibrated to measure the density and inner structure of the test material.
The Diagram below shows the Cross-Section of a Road with different Layers.
Road should have four layers at least as follows:
- Sub grade
- Sub base
- Base course
- Seal surface / Final surface (chip seal or Asphalts)
All roads, as other structure or equipment that are used regularly, will eventually deteriorate in quality over time from the natural disasters, weathering and heavy traffic loads. This requires routine repair works to maintain its strength and prolong its durability.
The Land Transport Authority (LTA) implements an annual routine maintenance program for all national roads. A total of 800 kilometres of road in Upolu is maintained annually and is divided into twelve (12) Road Routine Maintenance Zones. Each zone has an average of 66.7 kilometres of road.
All these zones are tendered out for bids annually for road construction companies (Contractors) to carry out repair works throughout the year. After the evaluation of bids, a contract is awarded to a company which will be responsible with all the repair works for the roads in its designated zone, until its contract expires after twelve (12) months.
The road repair works includes:
- Patching of potholes with bitumen premix material.
- Clearing of blocked culverts. Culverts are pipes made from concrete and meshwire.
- Repairing and replacement of damaged road signs.
- Cleaning and repairing of bridges and fords.
- Mowing of lawn and vegetation on the road side.
- Cutting down of trees/tree branches affecting the safety and movement of traffic.
- Clearing and cleaning of roadside drainages.
The LTA is responsible with the supervision and inspection of the routine repair works carried out by the contractors to ensure that the works are in accordance with the Standard Specifications for Road works.
The LTA inspects and assesses all the contractors’ performances of the routine maintenance works and pays the contractors accordingly. The contractors that do not perform satisfactorily in accordance with the Contract and LTA Standards will have its monthly payments deducted, and if persistently under-performed will have its contract terminated.
Shown in the following pictures are some of the works carried out in road routine maintenance.