Common utility duct - AbsoluteAstronomy.com

A common utility duct, sometimes called a common utility conduit, is any structure – above, on, or below ground – that carries more than two types of public utility

Public utility

A public utility is an organization that maintains the infrastructure for a public service . Public utilities are subject to forms of public control and regulation ranging from local community-based groups to state-wide government monopolies...

lines. However, the phrase often refers specifically to underground utility tunnel

Utility tunnel

A utility tunnel is a space for wires, conduits, pipes, and other conveyances used in the delivery of utilities with enough room for a human to enter. Modern pipes and cables need less attention and space than older varieties, so the construction of utility tunnels declined in the late 20th century...

Advantages of common utility ducts

The advantages of such facilities are the reduction of maintenance manhole

Manhole

A manhole is an opening used to gain access to sewers or other underground structures, usually for maintenance.Manhole may also refer to:* Manhole , a metal band from Los Angeles* The Manhole, a computer game...

s, one-time relocation, and less excavation

Building services engineering

Building services engineering, technical building services, architectural engineering, or building engineering is the engineering of the internal environment and environmental impact of a building...

and repair, compared to separate cable ducts for each service. One of the greatest advantages is public safety

Public Safety

Public safety involves the prevention of and protection from events that could endanger the safety of the general public from significant danger, injury/harm, or damage, such as crimes or disasters .-See also:* By nation...

. Underground power line

Electric power transmission

Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to Electrical substations located near demand centers...

s, be the ducts common or separate, prevent downed utilities from blocking road

Road

A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...

s, thus speeding emergency

Emergency

An emergency is a situation that poses an immediate risk to health, life, property or environment. Most emergencies require urgent intervention to prevent a worsening of the situation, although in some situations, mitigation may not be possible and agencies may only be able to offer palliative...

access after natural disaster

Natural disaster

A natural disaster is the effect of a natural hazard . It leads to financial, environmental or human losses...

s such as earthquake

Earthquake

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

s, hurricanes, and tsunami

Tsunami

A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

s. When they are well mapped they also allow rapid access to all utilities without having to dig access trenches or resort to confused and often inaccurate utility maps.

The following table compares the features of housing utility networks in single purpose covered trenches with the features of common ducts:

Trench	Duct
Long-term collaboration has not always been a high priority. So robust, precise location notice for older utility trenchs was often not provided or maintained, and older trench locations are often unknown.	Ducts are often used where developing authorities value the long-term benefits of utility co-location. That focus on long-term collaboration often includes greater emphasis on making duct locations easily known.
Single-purpose trenches encourage a utility to follow a single-minded route to shorten runs and save initial installation costs for that particular utility. But uncoordinated routing encourages spatial chaos, using more space than if trenches were highly parallel, and greatly increasing the overall encumbrance on surrounding development.	Ducts demand coordinated, highly collinear routing, reducing the overall encumbrance on surrounding development.
Even if parallel, trenches occupy more surface area. The surface area they use encumbers the area available for all forms of property development and construction with the burden of avoiding or moving the utilities.	Ducts are typically cylindrical, greatly increasing the volume of network resources per unit of surface area occupied.
Access to a trenched network typically requires locating the utility network, cutting open the road or pavement surface, breaking open the concrete platform and excavating a trench, followed by reinstatement of the trench, concrete platform and road surface afterwards. (This is where most of the financial cost of network renewals and maintenance is incurred.) Road surfaces can be seriously damaged by frequent trenching, requiring more frequent resurfacing. In the process, pavement slabs are often broken and badly aligned. UK roads are subject to 5 million roadworks per year (mainly for utility works).	Utility networks in ducts typically include designed-in access points (like those now used by British Telecom). Where ducts and access points are installed, excavations are rare and recurring maintenance costs are lower.
Maintenance of networks in trenches requires re-digging and restoring the trench and any roadbed above it. Road users suffer repeated delays from roadworks, particularly in dense cities. Roadworks for trench adjustments also require large quantities of sand, aggregate, cement, tarmac and marking paint.	Ducts allow maintenance through their access points. Since access points mostly obviate new roadway intrusions, traffic delays from duct-related roadworks are greatly reduced. Not disturbing roadways means network adjustments require materials only inside the ducts.
Rural properties are often denied access to gas or cable telecom because the cost of new trench deployment cannot be economically justified independently of other networks. Rural networks for electricity and telecoms are often above ground, with increased risk of disruption, even though there are usually local underground water and gas networks serving the same properties.	Sharing the higher initial installation cost of ducts across all services could make rural service more economically feasible. Where ducts are used, all networks are typically underground in multi-purpose ducts. Redundant above-ground electricity and telecom poles are usually dismantled, increasing safety and reducing natural disaster impacts.
Without common utility ducts, new types of networks require new trenches or independent ducts. Such expansions have already included cable telephone and television networks. Proposed local heat transfer systems and more localised, reconfigured power generation systems would also require new trenches.	Common utility ducts are designed to accommodate anticipated new and evolving networks.
The high thermal conductivity of soil would require extreme insulation for heat transmission through trenched networks.	The low thermal conductivity of air in ducts allows heat transmission with less insulation and cheaper standoffs.

Examples of common utility ducts

Many examples of common utility ducts are found in Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, where government officials have sought ways to reduce the catastrophic effects of earthquakes in their tectonically active

Plate tectonics

Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

country. Their use, however, is not limited to that country and there are many examples of such common utility ducts. These include:

Incorporated with Xinyi
Xinyi Line (TRTS)
The Taipei Metro Xinyi Line is a high-capacity, rapid transit line currently under construction. It is the extension of the Tamsui Line and part of the Red Line. Upon completion, the line will alleviate congestion on the Nangang Line by providing another east-west route through the Xinyi District...

and Sonshan MRT
Taipei Rapid Transit System
The Taipei Metro, more commonly known as the MRT or formally as the Taipei Rapid Transit System, is a rapid transit system serving metropolitan Taipei in Taiwan. The system is built and operated by the Taipei Rapid Transit Corporation and consists of 89 stations and of revenue track...

rapid transit
Rapid transit
A rapid transit, underground, subway, elevated railway, metro or metropolitan railway system is an electric passenger railway in an urban area with a high capacity and frequency, and grade separation from other traffic. Rapid transit systems are typically located either in underground tunnels or on...

lines in Taipei, Taiwan
Azabu-Hibiya Common Utility Duct in Tokyo, Japan
Minatomirai District lines in Yokohama, Japan
Poundbury
Poundbury
Poundbury is an experimental new town or urban extension on the outskirts of Dorchester in the county of Dorset, England.The development is built on land owned by the Duchy of Cornwall. It is built according to the principles of Prince Charles...

Village in Duchy of Cornwall
Duchy of Cornwall
The Duchy of Cornwall is one of two royal duchies in England, the other being the Duchy of Lancaster. The eldest son of the reigning British monarch inherits the duchy and title of Duke of Cornwall at the time of his birth, or of his parent's succession to the throne. If the monarch has no son, the...

, Prince Charles' master planned community in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

incorporates common utility ducts
"Utilidor
Utilidor
A utilidor is a utility corridor built underground or aboveground to carry utility lines such as electricity, water and sewer. Communications utilities like fiber optics, cable television and telephone cables are also sometimes carried...

s" in Disney theme parks
German cities such as Bremen
Bremen
The City Municipality of Bremen is a Hanseatic city in northwestern Germany. A commercial and industrial city with a major port on the river Weser, Bremen is part of the Bremen-Oldenburg metropolitan area . Bremen is the second most populous city in North Germany and tenth in Germany.Bremen is...

. This city has near perfect surfaces on its footways, cycleways and streets. Virtually no repairs or disturbances are visible. The number of streetworks in progress is trivial. This can only be achieved by (a) vehicles not driving on footways or cycleways (b) utility ducts making it unnecessary to disturb the surfaces in order to access the networks below for repairs, maintenance and alterations. Utility networks are housed in a cluster of pipes which are located under footways and cycleways.