How many public agencies does it take to give Arboretum Drive a facelift? Five, yes five – Seattle City Light, the Seattle Department of Transportation (SDOT), Seattle Parks and Recreation, Washington State Department of Transportation (WSDOT), and the University of Washington.
Why so many? The Arboretum is unique – a hidden gem tucked away on the shores of Lake Washington just south of WSDOT’s SR 520 Evergreen Point Floating Bridge. Jointly managed by the UW and the City of Seattle, the Arboretum’s 230 acres are a dynamic combination of plants found nowhere else.
Together with City Light, the recent work was coordinated and funded by SDOT, Seattle Parks and Recreation, WSDOT and the UW. During the past summer and fall, the City and State partnered with the Arboretum to add a New Zealand Garden in addition to replacing streetlights; spot paving along Lake Washington Boulevard; installing traffic calming devices; adding bicycle sharrows on the roadway; making crosswalk improvements, augmenting signage and other pedestrian enhancements; and trimming trees and maintaining the landscape.
By working together, the six entities were able to accomplish a significant body of work while minimizing disruptions to park traffic and SR 520 commuters during peak travel times on Foster Island Road on the north end of the park to Arboretum Drive, on the south end of the park, and on Lake Washington Boulevard.
The streetlight work involved far more than just replacing light bulbs; it included replacing the old underground direct-bury electrical cable with new cable, conduit, handholds, foundations, grounding/bonding, light poles, and 73 light-emitting diode (LED) boulevard-style lights. Most of the ornamental high-pressure sodium luminaires and laminated poles were installed in the 1970s and at the end of their useful lives and failing.
The project replaced old streetlights with boulevard-style LEDs that provide better light quality. The LEDs offer a light that’s a whiter/cooler color rendering spectrum, similar to moonlight, which improves safety because of depth of field and peripheral vision is enhanced without the color distortion.
The LEDs are energy-efficient by providing a more stable, “cooler” burning light that lasts three to four times longer than the old luminaires while the greenhouse gas emissions are reduced during manufacturing and usage. In addition, heavy metals were removed that are found in high-pressure sodium lighting. These new lights require fewer service vehicle trips for repairs, which means a further reduction of carbon each year. Their better service reliability and lower maintenance costs, save taxpayer money over time. City Light also used a boring and trenching technique to install the conduits to protect the Arboretum’s historic trees from root damage.
The Washington Park Arboretum safety and landscape improvements support and enrich the park’s master plan goals of education, conservation, providing recreation and visitor services, and rehabilitation of the Arboretum infrastructure for generations to come.