permanent mobile maintenance platform design for bridges

I'm having trouble understanding what is meant by "permanent mobile". Do you mean permanently mounted to the bridge, but able to move along it?

There are many mobile inspection vehicles for sale or rent.

Thank you for the response OSUCivlEng. Yes this platforms will be permanent mounted on the bridge and need to be mobile to perform inspections and maintenance works for the entire span as per contractors request.
They don't want a mobile truck inspection for this.

You mean a traveller. I've never designed one but have rode on a few. They are usually made of small wide flange or channel sections supporting metal grating. The sides are usually angles. The Travellers ride on rails that hang from either the web or bottom flanges of the supporting girders. I have to look through my files, may have something. You're going to need a mechanical and an electrical engineer.

Bridgebuster's summary is correct.

I've never seen a design code or reference intended specifically for travelers. The closest I've come is some of the material for (underslung) crane wheel loads, which is an important design limitation. Otherwise, all the work I have done has been per AISC (and like BB, I've excluded the mechanical and electrical scope).

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The name is a long story -- just call me Lo.

@George89Ro - attached is a traveler rail drawing. A few years ago I did a job for a contractor involving a long span bridge that had several travelers. Mywork had nothing to do with the travelers. When I get I home tonight I'll take a look to see if any of the drawings provided to me show traveler details.

I don't have the traveler drawing but you can get a glimpse of it in the background. The platform with the yellow chain is a temporary platform. The part that appears to be an "upper level" is really a safety cage for the access ladder and a platform for some electrical equipment. This one has a horizontal frame as a bumper when it gets close to a pier.

I have never came across design code relating to this specific item, although in the past I have designed and used some.
The live load shall depend on intended use, and shall be 30-50 psf, plus concentrated 750-1000 lbs at any location, non-concurrent.
As travellers are installed on the long span bridges, these are not specifically covered by AASHTO, or other bridge codes, so the design specification shall be discussed with the bridge owner.
Other interesting aspects of the traveler design are the propulsion system and power supply, which could external, or internal by small generator installed on the platform. Catenaries are prone to corrosion and dirt, and coiling or folding cables tends to tangle frequently, so generator is typically a preferred choice.
There is some interesting link covering the subject:

Sounds like some type of P3 design/build/maintain deal if the contractor is asking for this. "every bridge and span in the project", how many bridges and spans and what type of bridges? Steel/concrete girder/truss/stay cable?

Also, from these things, you can't reach everywhere. You may have elements that require hands-on inspection and a snooper may be needed anyway. Talk to them some more about what they want/need and intend to accomplish. Depending on how many bridges there are, unique configurations of travelers you need to design/build/maintain and operating costs, they could be getting close to the cost of just buying a snooper (300K-500K).


IC