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Road Construction: Why road get damaged?

posted Sep 6, 2021, 8:10 AM by jeffery jim
My dad forwarded photos, a video and comments in our family group about a road which is badly damaged. Just like everyone else, there is certainly a genuine concern about safety as road users. Although my dad is not a civil engineer, he have some good ideas and reasoning which may deem valid to justify possible causes that triggers defects if not aggravating the road in a long run.

2. Construction of road is relatively easy by principle and concept where the thickness of each material can be calculated easily based on the CBR value for subgrade which essentially be the value for load bearing capacity. Another parameter which is vital would be the traffic volume in order to ensure the road would last as planned.

3. Throughout the road alignment, site investigations are conducted with miscellaneous type of test in order to ensure the existing bearing capacity is sufficient or else, treatments shall be provided through stabilization, replacement or reinforcement. Apart from bearing capacity, the soil material is scrutinized to ensure that material is suitable and not of argillaceous in nature which can be broken down easily due to its weak matrix condition. Similar goes with unsuitable material which fits other definitions. These are predetermined throughout the process in periodical stages where soil properties are determined every 1,500 m3 of soil extracted from borrow pit.

4. After subgrade is treated and compacted, it requires one validation check. Earlier all QA and QC test have taken place by conducting Field Density Test when compacting a flight of 300mm for every 500m2 minimum as well as monitoring the movement via deep settlement gauge. Before confirmatory instruction is provided to proceed with subsequent layers, subgrade level shall be first tested for its in-situ CBR value, and then surveyed and dipping are conducted. Once this is done, proof rolling test (of 50 tonne load) by utilizing a 70 tonne tonne truck with load shall make it way in five to six different paths in traffic direction in order to check if there is rutting or settlement to the existing subgrade. After passing this test, only subbase can be placed to required thickness in specified flight thickness.

5. In many cases, most road constructions skipped this proof rolling test. It is a test that requires specific truck with such capacity or a retrofitted truck that can achieve the specification. Without conducting this kind of test, the subgrade bearing capacity is in doubt even though in-situ CBR indicate otherwise.

6. There are more than just a single test to determine the durability and robustness of a constructed road. The said proof rolling test is the best foolproof test which can be deployed as final confirmatory test as part of QAQC but not the overall engineering works.

7. Engineering works may lead to many other issues when designers are not competent. Yes, most designers maybe professional engineers themselves but not many are learned geologist and geotechnical engineers. This is the main issue for substandard road design in our country. The inability to have proper design which lead to ineffective construction method and under/over costing of road construction.

8. Road construction is actually a very complex process where it requires and goes beyond engineers of all disciplines. They need to be a team of inter-discipline and learned professionals. The failure to integrate hydraulic and hydrology as well as environmental scientist will result in catastrophic water issues throughout the project duration. This have been the issue that cause many inconvenience to dwellers surrounding the project site.

9. Water is known as the main problem that can cause aggravation during construction for ongoing materials and work-in-progress if not planned according or protected thoroughly. Temporary water diversion and dewatering also caused environmental degradation although it maybe temporary or momentary. Coupled with lack of due diligence conducted prior to construction, issues will continue as hindrances or worst, hazards to third parties especially road users.

10. This is a short note about basic shortcomings during road construction. There are more but it would take many chapters to cover.

May be an image of one or more people, people standing and road

May be an image of outdoors

May be an image of one or more people, people standing and outdoors