>> Investigation into cracks points to execution
>> Thang Long Bridge to get another makeover
DTiNews had a discussion with Doan Minh Tam, Director of the Institute of Transport Science & Technology, the design and supervising consultant of the Thang Long Bridge reparation project, about the reasons behind the cracking problems on the bridge’s surface.
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| Doan Minh Tam, Director of the Institute of Transport Science & Technology |
Do you think it’s normal that Thang Long Bridge’s surface started cracking after only 2 months in operation?
- It’s very unexpected and abnormal to us. Had the cracks been found during the repairing period or right after the repair was done, we would have immediately discovered the causes.
When the rolling and pressing process for the stone mastic asphalt (SMA) was finished, the temperature was below 120C degree that’s why the quality of surface was affected.
SMA features depend on many factors and weather is among the key one. Could you foresee the situation before execution?
- No, we could not. Currently, SMA is used by many countries in the world. However, during the period where we were laying the SMA, there were many cold days and heavy winds on the bridge. We couldn’t do anything about the weather. It’s very difficult for us to change the construction schedule because we wanted to finish before Tet.
The Institute took responsibilities of researching about SMA, design and supervising consultation. Can you explain why the construction was conducted while weather conditions didn’t allow?
- We could not foresee the situation. It had never ever happened before. SMA was used for Thuan Phuoc Bridge in Da Nang but the execution was supervised directly by Chinese experts. However, for Thang Long Bridge, foreign experts just instructed us and transferred the technology.
What lesson can be learned from these mistakes on a project worth VND97 billion ($5 million)?
- Let’s not try to place a price tag on learning from mistakes. The contractor will take care of repairing flaws during the guarantee period.
How will flaws be fixed and what about its expenditure?
- Bad quality SMA layers will be removed. Flaws will be fixed using the right techniques with SMA materials in addition to water drainage solutions for drying out the surface.
There are about 200 square metres of broken surface so it will not be too costly. It will take some dozens of millions dong for materials and some expenditures for machines and labour. The repair will be conducted over the next several days and it’s expected to finish within one week.
The incident has become a big lesson and all relevant units must take responsibilities and learn from the mistakes that were made.
Thank you!
