Site Factors. Integration into Urban Context While HST aerial structure structures introduced into urban areas must satisfy their primary engineering function, they should also be designed with sensitivity to surrounding communities and businesses. Care should be exercised to avoid physically dividing communities and altering the character of neighborhoods. HST aerial structures and associated landscape and hardscape features should be judiciously placed, sized and detailed. Sun and Shadow Sun and shadow conditions will be altered by the introduction of HST aerial structures into the urban context. Portions of the community will be shaded by new structures. Consideration may be given to special spacing of HST aerial structure piers to reduce shadows at sensitive locations. Where wider trackways are required, such as at station approaches, individual girders may be considered to allow sunlight to penetrate between girder decks.
Site Factors. Urban Sites Just as the site conditions, context and span influence the choice of structural system for an urban HST bridge or overpass, these are primary determinants in aesthetic treatment of an HST bridge or overpass. Future land use must be considered; a HST bridge or overpass crossing industrial land today may cross over a housing development in the future. Urban character will change over time; HST bridges and overpasses must be designed with this fact in mind. Public exposure must always be a factor in aesthetic decisions. Whereas a HST bridge or overpass spanning a railroad switching yard may be seldom seen by the public, a HST bridge or overpass spanning a public highway will be viewed countless times each day and its exposure may warrant special design treatment. HSR 13-06 - EXECUTION VERSION Tsing Ma Bridge, Hong Kong Overpass in San Diego Urban Bridges and Overpasss Space Under HST bridges and overpasses Space beneath HST bridges and overpasses provides opportunities for development of parks and other public spaces. Where adequate height would allow sunlight to penetrate under an HST bridge or overpass, consideration should be given to developing public space beneath it. Park under Xxxxx Xxxxxx, Xxxxxx Xxxxxxxxx Xxxx Xxxxxx, Xxxxxxxx Space under Bridges and Overpasses Rural Sites A remote bridge or overpass in a rural setting may be viewed less frequently than an urban highway span. However, remoteness does not relieve the need for aesthetic care. In fact, a rural context often renders the aesthetic character of a bridge or overpass even more critical due to the importance of complementing its natural setting. HST bridge and overpass components should conform to the natural topography. Suburban Minneapolis Glacier Park, Montana Rural Bridges Abutments The hard, straight lines of a HST bridge and overpass structure should transition gently into the soft lines of the natural terrain of the countryside. Abutments are best left open and sloped to meet the underside of the girders. Natural Abutment, Spain HSR Retained Abutment, France HSR Abutments HSR 13-06 - EXECUTION VERSION
