It’s high time we put all utility lines underground

Each time a typhoon or earthquake of strong magnitudes strikes, large portions of our country go powerless because overhead cabling and wiring systems and lines can be felled or cut loose by strong winds, lightning and other hazards.

The case of typhoons “Odette” and “Yolanda” leaving whole areas without power, communication lines and other rendering utilities inutile are just a few examples of why those overhead electric poles and their heavy wires are impractical, if not outmoded.

These lines are also eyesores, especially if they are not neatly arranged—which is often the case—and there is a possibility of tripping if some branches of tall trees lean on these wires.

It is not wonder then that the Department of Public Works and Highways (DPWH) is proposing that all these utility lines, cables and wires (especially the heavy ones) be buried underground or what in civil engineering is called undergrounding.

Countries using underground lines

Japan, after World War II, installed power lines aboveground to save time as the nation eyed a quick recovery, even though gas and water lines remained underground.

Since the seventies, there have been increasing calls to move power lines underground partly to improve the scenery.

In Japan, not all the electrical and telephone lines are above ground. You will find parts of Kyoto, Nara, Kanazawa, and many other tourist cities that have some of their lines underground. They put the lines underground to enhance the old time feeling of parts of their city.

Some European countries, including the Netherlands and Germany, have made significant commitments to undergrounding. Burying power lines costs roughly $1 million per mile, but the geography or population density of the service area can halve this cost or triple it.

In Australia, an estimated 150 000 and 200 000 new homes are connected to underground power supplies each year and given several decades, this will result in a significant proportion of the national housing stock having underground connection

In the United Kingdom, some 8.3 million homes and businesses across London, the East and South East of England are still connected via thousands of overhead and underground power lines. Overhead electricity lines are usually held up by wooden poles or steel towers.

Bangkok, just like the Philippines, still use overhead power and utility connections because of frequent heavy rains and flooding. The ground is soft, ground loads are often changing, and there is lots of new building everywhere. Underground cables are going to be flooded, broken by ground movement, and dug up by backhoes at every building site they pass.

Benefits of undergrounding

In civil engineering, undergrounding is the replacement of overhead cables providing electrical power or telecommunications, with underground cables. It demonstrates the higher technology in developed countries for fire prevention and to make the power lines less susceptible to outages during high wind thunderstorms or heavy snow or ice storms.

An added benefit of undergrounding is the aesthetic quality of the landscape without the powerlines. Undergrounding can increase the initial costs of electric power transmission and distribution but may decrease operational costs over the lifetime of the cables.

Undergrounding is less subject to damage from severe weather conditions (lightning, cyclones/typhoons, other winds); it decreases risk of fire (overhead lines can draw high fault currents from vegetation-to- conductor, conductor-to- conductor or conductor-to ground contact); it has reduced range of electromagnetic field emissions and it needs a narrower surrounding strip of 1-10 meters to install (up to 30m for 400kV cables during construction) while overhead line requires a surrounding strip f 20 to 200 meters wide to be kept permanently clear for safety, maintenance and repair.

Also, underground cables have a much-reduced risk of damage caused by human activity such as theft, illegal connections, sabotage and damage from accidents.

Burying utility lines makes room for more large trees on sidewalks, which could be beneficial to the environment as well as increasing property values.

The aerial cables that carry high-voltage electricity and are supported by large pylons are generally considered an unattractive feature of the countryside. Underground cables can transmit power across densely populated areas or areas where land is costly or environmentally or aesthetically sensitive. Underground and underwater crossings may be a practical alternative for crossing rivers.

Disadvantages

Undergrounding is more expensive as the cost of burying cables at transmission voltages is greater than overhead power lines and the life-cycle cost is two to four times the cost of overhead power line.

Finding and repairing overhead wire breaks can be accomplished in hours but underground repairs can take days or weeks.

Operations are more difficult since the high reactive power of underground cables produces large charging currents and so makes voltage control more difficult. Large charging currents arise due to the higher capacitance. To avoid the capacitance issues when undergrounding long distance transmission lines, HVDC lines can be used as they do not suffer from the same issue.

Overhead lines can easily be uprated by modifying line clearances and power poles to carry more power but underground cables cannot be uprated and must be supplemented or replaced to increase capacity. Transmission and distribution companies generally future-proof underground lines by installing the highest-rated cables while being still cost-effective.

Underground cables are more subject to damage by ground movement.

As underground repair and check- up require street digging, it creates patches and potholes, leading to bumpy and unsafe ride for cars and bicycles. Utility work also increase lane closure which leads to the traffic jam and increasing cost of resurfacing work by the local government.

The advantages can in some cases outweigh the disadvantages of the higher investment cost, and more expensive maintenance and management.

DPWH proposal

DPWH-National Capital Region Regional Director Nomer Abel Canlas said his office submitted to the DPWH Central Office a proposal for a feasibility study on making all electricity and communication lines underground in NCR.

His office is proposing to start the project along major roads such as Epifanio de los Santos Avenue (EDSA), Radial Road 10 (R-10), and Circumferential Road 3 (C-3).

“One of our visions for the NCR is to put all lines underground,” he said, citing safety, convenience, and aesthetics.

“Let’s look beyond 2022, and we may see more posts and cables, which are unsightly. It would be a lot nicer if we put them underground,” he added.

Apart from the aesthetic advantages, underground cables also help avoid accidents like electrocution.

“Utility companies will no longer worry about acquiring road right-of-way for their utility posts,” he said.

Various groups have urged the government to consider underground cables as part of its disaster resiliency strategy to prevent massive blackouts during calamities like Typhoon “Odette.”

Bagong Henerasyon Partylist Representative Bernadette Herrera-Dy filed House Bill 5845 which proposed to require companies that use wires, including those that supply power, internet services, telephone, cables to the public, to relocate their wires underground within 10 years of its implementation.

Filed in 2019, the bill, also known as the “Nationwide Underground Cable System Act,” is still pending with the House Committee on Information and Communications Technology.

Utility service providers have said they are willing to shift to an underground cable system, but this would require government subsidies and proper planning on the part of government officials.

Tags: #utilities, #electricity, #infrastructure, #undergroundlines