When planning bridge replacements, railroads are increasingly looking at ways to inspect the underside of the structure with a minimal disruption to rail traffic. A traditional inspection means using Snooper Trucks that reduce or even halt traffic for extended periods of time. This can create a scheduling conflict to balance rail traffic, and it is challenging to request more time to finish inspecting the structure. Hanson design teams have been working with railroads to deliver simple systems that employ ladders to access bridge undersides and require minimal, if any, disruption to rail traffic.
Ladders have become the typical means used to access the bottom of the bridge to inspect the components of the structure, including the bearings, caps, deck, bracing and beams. Safety, ease of access, maintenance, Occupational Safety and Health Administration (OSHA) requirements and comfort are important considerations for access ladders. Ladders can be designed with rungs for environments that get ice and snow, but steps may be preferred where these conditions do not exist. Anti-slip coatings on the ladder are key to prevent the inspector from losing their footing or grip.
From left to right: an inclined ladder; access provided at each pier; and a vertical ladder (at the middle pier) and inclined ladders, all at a rail bridge in Media, Illinois.
Whether to use a vertical ladder, an inclined ladder or a caged ladder must be considered when meeting OSHA’s required guidelines. A ladder with an incline is preferred for the comfort of climbing. It is important to discuss how fall protection will be used when selecting a system with a retractable cable, a vertical safety cable system or the use of fall gear with pelican hooks. The vertical safety cable system with a tie-off device becomes troublesome with where it clips to the safety harness and when somebody leaves the tie-off clip at the bottom, because the only way to pull it back up is with a rope. The type of harness required for this system is different from a normal fall arrest harness.
The transition from the top of the ladder over the handrail is a tricky location. Depending on the setup, the inspector may have to awkwardly stretch from the ladder over the handrail to access the catwalk. The best design has a platform at the same level as the top of the handrail, which allows the inspector to remain facing the ladder and maintain three-point contact while stepping down to the catwalk.
Contact Jason Cunningham at jcunningham@hanson-inc.com or Drew Dragoo at ddragoo@hanson-inc.com for details on Hanson’s bridge inspection solutions.