1666913 - Elevated Guideway Design Considerations

Elevated Guideway Design for APM Systems is often completed by Bridge Engineers unfamiliar with APM System requirements and their impacts on the guideway bridge structure.  Often times, new APM systems are procured with one contract for the guideway structure and a separate contract for the APM system.  This allows for conventional bridge contractors to bid on the guideway, but it can present challenges in coordination of requirements.  There are a few key issues that should be understood by the guideway designer and how the APM system will affect the guideway design.  This presentation will compare typical highway bridge design considerations with APM System guideway design considerations.  The key differences can be broken down into 2 main categories; geometric and structural. 

First, geometric considerations for an APM guideway include: space requirements for guideway equipment, switches, emergency egress, maintenance platforms and interface issues with stations.  If there are 2 or more parallel tracks, the vertical profile geometry can get complicated.  Most APM guideways have a running surface separate from the bridge deck and this running surface should be within a specified height range.  The separate running surfaces also present challenges with bridge deck drainage.  Also, the track elevation of the left track and right track should be similar at any given point. The typical highway bridge geometry is governed by roadway design requirements. 
Second, structural considerations are distinct between a highway bridge and an elevated guideway.  The elevated guideway must be designed to handle the concentrated guidance loads from the APM system as well as wind, braking, traction, centrifugal, seismic and other typical bridge loads.