Information about Common Utility Duct

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 lines. However, the phrase often refers specifically to underground tunnels.^[1]

Advantages of common utility ducts

The advantages of such facilities are the reduction of maintenance manholes, one-time relocation, and less excavation and repair, compared to separate cable ducts for each service. One of the greatest advantages is public safety. Underground power lines, be the ducts common or separate, prevent downed utilities from blocking roads, thus speeding emergency access after natural disasters such as earthquakes, hurricanes, and tsunamis. 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 paragraphs compare the features of housing utility networks in single purpose covered trenches with the features of common ducts:

1. Trench - The precise locations of many utility networks are unknown. They also consume excessive space. This hampers maintenance and extension of the networks and all forms of property development and construction. Duct - The locations of the ducts and thus of the networks are much easier to monitor. Utility networks occupy less space.
2. Trench - Every access to a network requires 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.) Duct - Access to networks is via access points (like those already in use by British Telecom). Where ducts are installed, excavations are a thing of the past.
3. Trench - Road surfaces are damaged by frequent trenching. More frequent resurfacing is required. Pavement slabs are broken and badly aligned. Duct - Road surfaces and pavements are not disturbed to get at utility networks.
4. Trench - Some country’s roads are subject to 5 million roadworks per year (mainly for utility works). Duct - Huge reductions in the number of roadworks where ducts are installed.
5. Trench - Road users suffer repeated delays, particularly in cities. Duct - Traffic delays from roadworks for maintenance of networks are greatly reduced.
6. Trench - Non-renewable sand, aggregate, cement and tarmac are consumed in large quantities. Duct - Huge reductions in non-renewable materials usage.
7. Trench - Water companies project infrastructure renewals expenditure of £2.2billion over five years . Electricity companies are allowed to charge customers an additional £5billion over five years for networks maintenance. Duct - Huge reductions in the cost of maintaining networks and hence in charges to consumers. The usage of ducts would be covered by annual rentals which would be far less than today’s costs.
8. Trench - Rural properties are denied access to, usually, gas or cable because these cannot be economically justified independently of other networks. Duct - All services could be supplied to rural properties through single multi purpose ducts.
9. Trench - 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. Duct - All networks are underground in multi-purpose ducts. Above ground electricity and telecoms poles are redundant and dismantled.
10. Trench - New types of network require new and independent trenches or ducts. These have included cable telephone and television and potentially include local heating transfer systems from offices to residential. Power generation may also become much more localised, requiring reconfiguration of electricity distribution networks. Duct - New and evolving networks can usually be accommodated in existing ducts.
11. Trench - The heat generated by underground networks is wasted as it remains trapped underground. Duct - The heat generated by underground networks housed in ducts could often be extracted and cycled into space heating systems.

Examples of common utility ducts

Many examples of common utility ducts are found in Japan, where government officials have sought ways to reduce the catastrophic effects of earthquakes in their tectonically active 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^[2] and Sonshan MRTRapid transit lines in Taipei, Taiwan
• Azabu-Hibiya Common Utility Duct in Tokyo, Japan^[3]
• Minatomirai District lines in Yokohama, Japan^[4]
  • Poundbury Village in Duchy of Cornwall, Prince Charles' master planned community in England incorporates common utility ducts^[5]
  • "Utilidors" in Disney theme parks
  • German cities such as Bremen. 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.

  See also

  • District heating
  • Electricity distribution
  • Empire City Subway
  • Public utility
  • Tunnel
  • Utility tunnel

  References

  1. ^ Taipei Gov Website
  2. ^ MAA Website
  3. ^ BigEmpire.com Website
  4. ^ Yokohama Landmark Building Website

5. ^ Mitchell, Sandy. "Prince Charles is not your typical radical." National Geographic. May 2006. [1] Accessed online 9/14/06