UNDERGROUND UTILITY TUNNELS IN AN INTEGRATED URBAN UNDERGROUND SPACE DEVELOPMENT PLANNING

                                                              

UNDERGROUND UTILITY TUNNELS IN AN INTEGRATED URBAN UNDERGROUND SPACE DEVELOPMENT PLANNING

Associated Research Centers for the Urban Underground Space (ACUUS)
Solution proposed by: 
ACUUS and other metropolises already provided by such a solution
In a Nutshell: 
Underground combined utility tunnels offer the advantage of hosting multiple services’ infrastructures inside an accessible and safe space, and of allowing regular inspections, maintenance and easy replacement. Very high safety results are obtained by moving inside tunnels the aerial electricity lines that are present in streets of cities
Where and When: 
This solution has been implemented since many decades in Europe (e.g. Berlin, Helsinki, Stockholm, Madrid and Barcelona), and more recently in North America and Asia. Under specific national and local regulations, utilities companies adopted such a solution for transporting water, electricity, steam, compressed air, telecommunication cables, natural or city gas.
Challenges: 
Due to the urban areas expansion, underground networks have been gradually added leading to the so called ‘‘spaghetti subsurface problem”. Multi-utility tunnels (also called utilidors) represent a sustainable solution that permits simple/safe operations on the infrastructures, avoiding the recurring street works that are necessary for direct burial trenches. Initial investment costs are higher than for direct burial but, since tunnels have a very long life, they are quickly compensated by very low costs for maintenance and repair. Moreover, the solution is incomparably safer from any point of view: ruptures, fires, earthquake and also more convenient for interventions after natural disasters.
Innovation: 
For areas where many infrastructures are still directly buried (like pipes for water, gas, district heating/cooling) or are aerial (like electricity and telecommunication cables) the utility tunnel represents a unique innovation that is guaranteed by previous experiences. The streets are no more involved in recurrent excavations that impact on traffic and walking, on regular activities of the shops and produce noise and pollution for inhabitants. Excavations are very infrequent; repairs and new installations of cables/ pipes require less working time and material use. When and where significant urban renewals are foreseen, suitable planning for utility tunnel layout should be made.
Concept: 
Multi-utility tunnels are solutions for avoiding utilities congestions. They are particularly useful in any areas where traffic is critical and utilities are dense. This solution allows having a direct access (without digging) to all the infrastructures located into the tunnel and to operate any kind of operation (repair, maintenance, substitution of components, ..) in a protected, ventilated, illuminated and monitored space, without impacting on the surrounding environment (people, work, activities,..). The damage to other infrastructures due to the works in the streets is avoided. Moreover, utility tunnels contribute to enhance the aesthetic of cities. For previously explained concepts, benefits can be perceived by citizens (beautification of the built environment, reduction of traffic interruptions, etc.), by buildings inhabitants/workers (reduced noise and safer energy distribution) and governments agency and municipalities (network management planning is easier). Networks sited underground are also prevented from climate/vandalism damages.
Description: 
The solution requires that, through digging or better, with trenchless technologies, is built an underground tunnel sufficiently large for hosting, if possible, all the infrastructures, in separated sections for pipes and cables and with a central passage for allowing a continuos inspections and the transport of materials. The tunnel must be provided wuth lighting systems and ventilating devices and conducts. The control and monitoring must be guarantee by Closed Circuit TV installations (CCTV) connected to the control room of the Utility charged for the general tunnel operations. Considerind that all the infrastructers are concentrated in an unique site, for safety reasons, a strict control system should be ensured in order to avoid sabotages or vandalism. Moreover, to avoid the principal risk an hazards related to energy transport on other infrastructures, electrical, gas and other infrastructers should be de-energized where possible.
Impacts: 
In all the urban areas where this solution has been adopted, a remarkable improvement in infrastructures management has been verified, from the point of view of costs and time required for any kind of operation, as a result of the absence of interferences among lines and pipes and constraints due to the usual street activities. Concerning electricity, the number of blackout events that where very frequent in the past before the enclosure of the lines into the tunnel, has been significantly reduced.

Photo Gallery

Urban problem: Worker in the city of  Allahabad, India (Source: Rajesh Kumar Singh/AP)
Urban problem: The spaghetti subsurface problem  (http://www.utswot.upv.es/about.html)