What are these elaborate 'access panels' for?

[Hughby]

First post after lurking for a while.

As well as being a Rail enthusiast I cycle/walk in the MK area which means I cross the WCML regularly. I often come across bridges with what appear to be access panels that make little sense (to me!).

Any ideas? They don't seem to pass through to the 'railway' side of the structure (see photos).

Hughby

 

[jonty14]

Very interesting. Could they be repair patches?

 

[HugePilchard]

Looking at the pattern of them, they seem to be symmetrical around the circular plate on the sixth panel in from the right.

Unless someone knows better, I'd say that they're just there because someone thought it would look good.

 

[Elecman]

Access hatches for internal inspection I would suggest

 

[Ploughman]

How thick are the girders?
If there is a double skin then access needed for internal inspection.

 

[edwin_m]

I agree, looks to me as if this is a girder that has been plated over and there is a void behind each panel where corrosion might not be detectable otherwise.

However I don't understand why some of them need much bigger hatches. I would have thought that if one of them needs a hole big enough for someone to access (which seems essential if corrosion is found and remedial action necessary) then they all do.

 

[swt_passenger]

I agree, looks to me as if this is a girder that has been plated over and there is a void behind each panel where corrosion might not be detectable otherwise.

However I don't understand why some of them need much bigger hatches. I would have thought that if one of them needs a hole big enough for someone to access (which seems essential if corrosion is found and remedial action necessary) then they all do.

How about this, although just a guess. Maybe they all started out with the small circular inspection holes, and as and when corrosion has been found in individual sections, then a much larger hole has then been cut to do that work?

 

[edwin_m]

How about this, although just a guess. Maybe they all started out with the small circular inspection holes, and as and when corrosion has been found in individual sections, then a much larger hole has then been cut to do that work?

Could be, although their symmetrical nature pointed out by a previous poster perhaps suggests something about the structure behind those panels that needs more attention.

 

[LWB]

If the structure is double walled then this RAIB report shows all too clearly why access is essential!

 

[mcmad]

Are the photos both of the same side of the bridge? Could there be services running in the void perhaps?

 

[John Webb]

Are the photos both of the same side of the bridge? Could there be services running in the void perhaps?

I would expect from the rivet locations that there are vertical 'H' section steelworks linking the two sets of panels together, so there won't be a continuous void - hence no services but the need for every section to have its inspection hatch. Probably of Victorian design, they had a knack, often lacking today, of making the necessary look attractive, hence the different shapes and symmetry of the hatches.

 

[Hughby]

Are the photos both of the same side of the bridge?

Technically no, but both sides of the bridge were the same with elaborate panels on the inside and none on the outside.

Thanks for your thoughts guys. Part of me is glad there is no obvious answer that I missed - the other part is still curious!

Hughby