Koi Koi Grace
by on March 4, 2019
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Constructability refers to the “readiness to be built’’ and to the process of reviewing and ensuring that a particular transmission line project can be actually built as designed, given the numerous technical and non-technical parameters that control the construction phase. This “review’’ looks at the construction constraints, environmental barriers, political issues, risks and acceptance to local community.

 

a-) Construction considerations

The primary construction-related issue is availability of access roads, both temporary and permanent. These roads are used to move crew, vehicles, materials and equipment in and out of the construction site. Their secondary purpose is to provide maintenance access to the structures for repair and to the ROW in general. Access needs also vary depending upon the type of structure (pole, frame or lattice tower), function (tangent, angle or deadend) and foundation (grillage, direct embedment, concrete shafts or guy anchors). These considerations in turn will dictate the type and number of vehicles and equipment that must reach the work site. Use of cranes and helicopters for heavy construction impose additional challenges.

The work areas for conductor pulling and tensioning equipment must be integrated into access road plans. However, these activities are performed only during construction and therefore the access is temporary.

Constructability assessment also involves evaluating the process of hauling poles to the site. Concrete poles are about four to five times heavier than steel structures are difficult to handle and move. Lattice steel towers, which are typically set on concrete shaft foundations, require the most concrete at each tower site. If unguyed poles are used at line angles, this mandates drilled shafts due to large base forces.

Most utilities will have in-house procedures for inspection, assessment and maintenance and these are likely to dictate their choice of a structure type for a specific line. Steel or concrete structures require minimal maintenance while wood systems need frequent inspections and condition monitoring.

Because of difficulty procuring ROW or easements, and obtaining permits for new lines, many utilities strive to improve their future options by selecting structure types for current projects that will permit easy upgrading or uprating initiatives.

 b-) Environmental constraints

Topographic characteristics of the terrain often provide the most difficult construction challenges. Areas with steep slopes, erodible soils, sensitive streams, wetlands, restricted lands and habitats impose constraints on the process. Construction activities in the neighborhood of federally-protected lands and wildlife refuges require a wide range of government permits and adherence to agency-imposed work schedules.

 

 c-) Regulatory issues

Any potential crossing of public (state and federal) lands invariably leads to regulatory requirements, consultations and approvals. Prior to construction, the project may require several permits at various levels. For example, road and highway departments require permits for transmission line construction where the line crosses a highway or expressway. Areas attached to sensitive natural resources and recreational usage demand additional regulatory compliances.

 

d-) Public acceptance

Any project involving transmission line construction must take into account its impact on the residents of the area it covers and possible public opposition to the presence of large structures, noisy construction equipment as well as potential disruption to regular community activities. Most utilities conduct meetings to inform the public of their intended projects and seek their input and cooperation.

 

 

 

 

 

 

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