Underpass Illuminated

1^st Street SW Underpass
Calgary, Alberta, Canada

1^st Street SW Underpass, the busiest in a city of 1.2MM people, is the primary corridor between the Beltline Community and Downtown welcoming nearly 10,000 pedestrians daily. Beneath century-old CP Rail station and tracks, the underpass was dark, wet, and uninviting; pedestrians quickened pace through passage.

Challenges of water and darkness mitigation aside, the structure is considered a heritage resource limiting paint color selection (to dark grey) and mounting opportunities. Widths of sidewalks and traffic lanes were constrained to the original 100-year design.

The “sleeve” design, beginning as a marquee and flowing through the underpass, created refreshed surfaces, allowed water mitigation behind, and provided opportunities for artistic surprise; “hanging chads” on perforated panels form words visible at pedestrian view angles and “holes” provide view to mural beyond. iO 2.0 asymmetrics, safely located behind the panels, wash the super graphic wall with light. iO 1.5 symmetrics, located above the perforated panel ceiling, create luminance to view the structural deck. iO 2.0 symmetrics create uniformity on walk. Dimmable iO product allowed the lighting designer to tune the visual hierarchy of the pedestrian experience.

Linear traffic zone luminaires are adaptively controlled to higher roadway illuminance during daytime – lower at night – eliminating “tunnel” adaptation; strategically fit within the historic structure without impacting clearances. Direct view LED was integrated into the guiderail creating a visual horizon.

The all-LED project provides higher illuminance requiring less energy and maintenance.