Underground Engineering for Sustainable Urban Development (2013) / Chapter Skim
Currently Skimming:
5 Lifecycle Sustainability, Costs, and Benefits of Underground Infrastructure Development
5 Lifecycle Sustainability, Costs, and Benefits of Underground Infrastructure Development
Pages 125-144
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 125... ...
Literature concerning impacts of underground infrastructure on the lifecycle sustainability of urban development is relatively scant. More is known about monetary lifecycle costs and benefits, while less is known about long-term envi ronmental or social impacts.
|
From page 126... ...
Accordingly, this chapter is divided into sections that consider the lifecycle economic, environmental, and social impacts of underground development. This review of lifecycle costs and benefits is consistent with the committee's task to explore how use of the underground could increase sustainability.
|
From page 127... ...
Particular underground development can preclude other uses or make them more expensive to implement. For example, underground transportation tunnels such as the Boston Central Artery project required rebuilding and relocating exist ing underground utilities in the tunnel right-of-way.
|
From page 128... ...
In many environmental lifecycle assessment studies, environmental impact esti mates are limited to only a few critical categories of impacts, such as emissions of greenhouse gases and conventional pollutants. Assessing system interdependencies over the life cycle of underground infra structure is also an important and challenging part of assessing risk.
|
From page 129... ...
. A recent NRC study found that compact cities are likely to reduce vehicle miles of travel and both direct and indirect energy consumption and greenhouse gas emissions (NRC, 2010)
|
From page 130... ...
Use of underground space can reduce traffic congestion and the consumer costs noted by critics of compact cities while simultaneously achieving the travel and energy reductions identified by compact city proponents. Figure 5.2 shows the Boston Central Artery, which was originally built as an elevated structure through downtown Boston but was moved underground in the Big Dig project, resulting in a corridor of open space (NAE/NRC, 2003)
|
From page 131... ...
describes the importance of urban underground space planning. Initial costs for underground construction include those related to geological site characterization and management of geologic conditions, finding and relocat ing utilities, potential disruption to existing infrastructure due to utility strikes, requirements for engineered backfill, and traffic control along a horizontal align ment.
|
From page 132... ...
Table 2.1 lists a total of Underground Engineering Camera-Ready.indd 132 2/13/2013 10:54:33 AM
|
From page 133... ...
Because they are critical to infrastructure functionality and must be carefully selected and installed during initial construction, these and other operational costs usually are combined with direct capital costs in selecting the best construction alternative. Safety hazards and risks are inherent in all construction projects and need to be assessed during the design phase.
|
From page 134... ...
found that the conversion of unsightly overhead electrical lines to underground lines resulted in increased property values and improved aesthet ics within neighborhoods. Other lifecycle societal economic benefits include reduced outages, transmission losses, and greenhouse gases; reduced network maintenance costs; fewer electrocutions; and fewer motor vehicle collisions with poles (IFC Consulting, 2003)
|
From page 135... ...
However, these impact statements are prospective in nature to inform planning decisions, rather than retrospective assessments of actual environmental impacts from projects as built. For example, whereas many earlier environmental impact analyses did not include greenhouse gas emission effects, recent environmental impact statements address findings such as the 2009 finding by the EPA Administrator that greenhouse gas emissions (carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexa fluoride)
|
From page 136... ...
(2010) compared buried and overhead power distribution using Southern California Edison designs for medium voltage cables using a process-based lifecycle assessment per guidelines from the International Or ganization for Standardization.a The Figure shows the various process steps involved in the life cycle for the underground power distribution assembly.
|
From page 137... ...
In other words, well-planned underground construction supports a compact, well-functioning, livable, and sustainable urban environment. The pro tection and resilience of an underground structure may benefit the project owner, but if it affects the ability of society to function effectively, for example, after a Underground Engineering Camera-Ready.indd 137 2/6/2013 3:16:55 PM
|
From page 138... ...
Least disruptive construction methods are more likely chosen, avoiding the need to calculate social costs. Another issue worth noting is that construction and operation impacts of major infrastructure projects represent a moving target in terms of acceptable compromises for limiting impacts on neighborhoods.
|
From page 139... ...
. Allowing variety in design approaches based on a better understanding of how to create interesting and enjoyable underground spaces without large increases in cost or space requirements remains a challenge, as does quantifying the social costs and benefits over the life cycle of the infrastructure.
|
From page 140... ...
Retrospective, com parative studies of the costs and impacts of the various types of underground construction projects are needed. To be useful, these studies must be conducted in a comprehensive and scientific manner and must consider economic, environ mental, and social impacts.
|
From page 141... ...
2005. Quantification of social costs associated with construction projects: State-of-the-art review.
|
From page 142... ...
2008. Risk-based safety impact assessment methodology for underground construction projects in Korea.
|
From page 143... ...
:85-92. Underground Engineering Camera-Ready.indd 143 2/6/2013 3:16:57 PM
|
From page 144... ...
Underground Engineering Camera-Ready.indd 144 2/6/2013 3:16:57 PM
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.