Suspended Platforms – Deception & Canoe Pass + San Rafael Bridge
By Brandon Romero | December 27, 2022
Designing a suspended platform system presents unique challenges not commonly seen in other lines of engineering, which requires a different kind of in-depth plan behind each design. Like a well-constructed spider web, suspended platform systems typically consist of efficiently placed cables and chains working both together and against one another to create a balanced system workers are free to move along. It’s critical that each plan accounts for the flexibility, rigidity, and location of its components to ensure the end user does not get launched up towards the bottom of the bridge, hurled towards the guardrail or struck by oncoming traffic. DHC has been involved in all kinds of suspended platform systems throughout the United States, each presenting their own unique challenges.
DHC had the opportunity to work with Cekra, Inc. to develop and design multi-level suspended platform systems to be installed at the Deception and Canoe Passes in Oak Harbor, WA. Each level consisted of longitudinal deck cables running the length of each bridge, weaving around members of the main truss systems. Chain link fence spanned over the deck cables to form the walking surface. These platform systems were not for the faint of heart with the upper levels of each platform being upwards of 150’ above and with a clear view of the water below. All access levels were supported by four main tie-up cables that terminated to the stringer and floor beams of the main roadway. Limited tie-up availability and strict allowable bridge load ratings required careful consideration when determining equipment locations and allowable suspended platform live and debris load ratings.
In California, DHC had the opportunity to work with Safespan Platform Systems, Inc. and Allied Painting, Inc. to develop and design suspended platform systems beneath the Richmond – San Rafael Bridge (not pictured). Due to the length of the Richmond – San Rafael Bridge (just over 29,000 ft), each suspended platform system was upwards of 96,000 square feet which greatly exceeds the amount of access area evaluated in most temporary systems. With this much area to cover, limiting the amount of equipment to be used while also providing safe access to work locations provided a challenge. Throughout the main span of the bridge, westbound traffic drives above eastbound traffic which required a minimum clearance to be maintained for platforms beneath the westbound roadway. Efficiently specifying tie-up locations was crucial to minimize deck cable sag, avoiding a catastrophic collision between semitruck and workers on the platform systems, while also limiting the amount of equipment needed.
Suspended platform systems absolutely have their advantages, being lightweight, flexible, and able to cover vast areas. To ensure these advantages are properly utilized with minimal risk to the end user’s health and wallet takes careful consideration throughout the design process. DHC takes pride in helping the construction and renovation community with hundreds of these projects, taking on unique challenges and providing thoughtful solutions.