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 No central authority is needed to manage the stakeholders.

3.1.1.2 Disadvantages of Trenching (direct burial) include:
 Maintenance costs are higher. Damage to one utility during repair or installation work on
another utility is more likely because location information is not shared well among stakeholders
 Robust, precise location records for older utility trenches are often not provided or maintained,
and older trench locations are often unknown. Low levels of collaboration among stakeholders
is a limiting factor [b‐3]
 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 parallel [b‐3]
 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) [b‐3]
 Maintenance of networks in trenches requires re‐digging and restoring the trench and any
roadbed above it. This is often performed in two steps. For example, a temporary layer of tarmac
is laid so to allow the soil underneath to stabilize and then, after a few weeks, the road is re‐dug,
the soil is pressed again and the final layer of tarmac is put in place. 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 [b‐3]
 Rural properties (e.g., SSC suburbs and periphery locations) are often denied access to services
such as gas or cable telecom because the cost of new trench deployment cannot be economically
justified independently of other networks. Therefore 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 [b‐3]
 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 localized, reconfigured power generation
systems would also require new trenches [b‐3]

 The high thermal conductivity of soil could cause overheating problems, e.g., from electricity
cables.
3.1.1.3 Example of trench sharing

The following extract from [b‐4] provides an example of trench sharing practice in the UK where the
trench is backfilled after the work is carried out. It also provides an example of cooperation among
stakeholders to save cost.
"Trench sharing may be beneficial in reducing disruption to both vehicular and pedestrian traffic, as
well as offering cost savings in construction methods and reinstatement liability for utilities. Trench
sharing can also be useful in maximizing the limited available space in the highway.
 Wherever practical and appropriate trench sharing should be considered
 When trench sharing is an option it is essential that early consultation takes place with
representatives from relevant authorities and all other interested parties

394 ITU‐T's Technical Reports and Specifications