Hawaii Deep Water Cable Program : visual impact analysis of proposed 300 kVdc line

Abstract

This report investigates the potential visual impact of the proposed Hawaii Deep Water Cable Program 300 kVdc overhead transmission lines which would cross portions of Hawaii, Maui, and Oahu. It does so by examining the three major components which affect visibility: the observer, the object and its setting, and the interrelationships between these components. The potential corridor areas on each island are categorized into four "landscape types", based on landform and landcover characteristics. Each landscape type is evaluated in terms of its visual absorption capability and screening opportunities. The distance relationship between the observer, object and setting is also described. The overall relationship between the landscape characteristics, the project features, and viewer characteristics determines the project's degree of visibility. By modifying the components affecting visibility, potential visual impacts can be avoided, minimized or reduced. Numerous mitigation measures are discussed and illustrated, relating to alignment location within a particular landscape setting, structure design, right- of-way clearing and maintenance, and construction practices.