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INSTALLING underground power lines and communication cables is among the top goals cited by Bangkokians to improve their city. Not only would the move beautify the street scape, it would also boost public safety, ending news reports of accidents or natural disasters causing power poles to fall on people, causing death or injury.
Attempts to put wires underground were initiated in 1984 with the project to transform areas of Bangkok into wire-free zones underway, including a stretch between Victory Monument and the Lat Phrao intersection.
The Nation interviewed experts from the Metropolitan Electricity Authority (MEA) to learn about the project. |The MEA is following a five-step |protocol:
First, survey the infrastructure and electrical systems in the target area. Then, make an action plan and select appropriate materials.
Third, install a replacement power distribution system with underground wires.
The fourth step, shift the power distribution system from wires on poles to underground wires, which is referred to as “throwing the switch”.
Last, remove the wires and power poles. Installing the replacement distribution system, the third step, can be done using one of three methods: an “open cut”, which is a noisy method that creates an open trench; “horizontal directional drilling”, a steerable, trenchless method using a bentonite clay solution that is used in excavation; or “pipe jacking”, which involves driving a pipe string from the launch shaft in the direction of the target shaft.
Once the pipes for wires or cables were in place, another team would come in to install waterproof wires and related equipment. The team would also use unit sub-stations that support power from the MEA, which adjusts the voltage from 24KV to 220V for distribution. The team would also test the wires by using the Oscillating Wave Test System before the power distribution shift – the target area’s houses would still have a power feed, except for a brief period during the system shift.
When a future problem arose, officials would use the Time Domain Reflection device to release waves into electrical wires to detect the problem spot so they could precisely repair it.
Once the power distribution has shifted, MEA would remove its wires and equipment from the poles and ask other communication service providers to do the same, said Prasong Khumprasert, head assistant of the agency’s Distribution System Administration. Then poles would be removed.
MEA would either use a hydraulic truck or a hydraulic cylinder device to remove the pole, he said. Safety is a priority for the agency.
“MEA’s power pole removal would have the target spot and nearby traffic lanes blocked from other people’s access for an appropriate time period during the pole removal. The uprooted poles would also be take out by truck immediately,” he said.
The September 13 incident in which a power pole fell near Sanam Pao Skytrain Station (but caused no injury) stemmed from the other operator’s imbalanced cable removal, he said.
On September 1 last year, MEA joined with four agencies to sign an agreement to put wires and cables underground. They were the National Broadcasting and Telecommunication Commission, the Royal Thai Police, TOT PCL and the Bangkok Metropolitan Administrative (BMA).
Starting October 1, agencies would no longer work separately on underground wiring. They would now coordinate, integrating their burial of wires and cables, said BMA Deputy Permanent Secretary Wanchai Thanomsak, speaking in his capacity as project co-ordinator.
The BMA, as project host, planned to have three levels of wires: for power lines on the bottom,s fibreoptic cables in the middle, and water pipes nearest the surface. Wanchai said the agency has proposed the “pipe jacking” approach be used in high-traffic areas, and the cheaper “open cut” method in the suburbs.