Preserving and keeping each type of roadway, roadside, structures as nearly as possible in its original condition as constructed or as subsequently improved and the operation of highway facilities and services to provide satisfactory and safe transportation, is called maintenance of Highways.
Factor Affecting Road Maintenance:
Generally following factors affect the maintenance of pavements.
Increase in the intensity of traffic.
Since we know that there is increase in road transport per year about 8%. Hence this is the most important factor, which affects the maintenance of roads.
Inadequate Thickness of Pavement.
As already discussed adequate thickness of pavement is essential. If the adequate thickness is not provided, it will result frequent pavement failure, unevenness and heavy patches.
Effect on No of lanes.
The road research laboratory has established by experiments that concentration of road is almost 4 times larger on a single lane pavement than a double lane pavement section. Thus the distress and maintenance on single lane pavement are higher than double lane pavements.
Types of Highway Maintenance
Generally following type of maintenance operations are adopted:
Routine or periodic maintenance.
Since all types of highway are exposed to the adverse climate condition and moving traffic, they would positively wear out. Thus for economy, they need maintenance before further deterioration. Under this category of maintenance generally following works are carried out.
- Up keep of carriage way.
- Maintenance of side drains as clearing of silt and maintain proper slope.
- Maintain of shoulders and sub grade.
- Of other ancillary work such as bridge etc.
- Improvement of highway geometric and traffic controls etc.
Special repairs are carried out for special problems and when occur due to the failure of pavements. Sometimes repairs are needed for some sub surface drainage system and cross structures
However care should be taken about a few things while the construction of the highway. Some are listed below:
- Adequate drainage system should be provided that has a design flow that could last for the life time of the project. On the Ring Road Hayatabad Peshawar, there is no such provision, which at times, cause the water table to rise up and affect the pavement foundations. Also the area comprises of field and crop lands, so the water input is more which needs to be removed, otherwise it will be danger to the sub grade.
- Proper sloping should be provided on the road surface in order to remove the rain water efficiently.
- Material of use should be in the nearby of the project area, so that there should be no delay in construction period.
- To make sure that the material reach to the site in the time when needed and neither neither earlier nor later than that.
- In case of asphalting, the temperature at the time of the laying of material should be within limits and accordance to the standards.
- The pavement should be design in accordance to maximum expected axle loading in a certain region and not more than that load should be allowed to pass over it. In Pakistan, the axle loads for which the roads are designed are normally taken to be carried out at some specific intervals.
- Grade of bitumen is the most important thing to be noticed. Proper grading criteria should be adopted in accordance to the climate conditions, so the selection of the proper grade of bitumen is a problem.
- Continuously driving on the same lane should be avoided in order to prevent the rutting failure.
- Proper compaction is the key to success in the highway design.
- If the soil is not of enough strength, it should be improved by adding some reagents. Also if required, soil can be imported from other places.