Wednesday, 21 May 2014

Busway damage - pictures

I've been out a couple of times in the past few weeks, and here are some of the shots I took (all taken from the bridleway).

Damage falls into various categories:

a) kerb damage

b) beam-end damage

c) step-damage (rubber pad fall-out)

I've also included some examples of pock-marking and surface stones, which might in the long-term cause issues of unevenness.

Kerb Damage:

i) to kerb-top

 ii) to side-wall (location west of Histon)
These are more extreme examples, but in general I wonder how long it will be before the kerb-wall starts to become as rough as the main running-way. The kerbs are smooth at the moment, but will the guide-wheels start to wear out much faster once the surface they run on becomes rough?

Beam-end damage - caused by expansion in hot weather

i) just east of Histon Stop - this one had only just occurred when I saw it
 ii) this type of damage possibly caused by small stones falling off and getting jammed between the beam ends, then causing further damage as and when the beam expands with heat.

Step-damage (rubber pad fall-out)

location: Trumpington


 Now some areas where the top surface has worn away, exposing more aggregate. How long will it be before these stones start popping out, and if so, will it produce an uneven surface over time?

 ...or, like this bit (with different concrete construction), will none of them pop out?

Comments appreciated!

1 comment:

  1. Some pure guesses (and IANAE):

    They will not be too bothered about the surface finish, unless it reduces the cover enough to cause the rebar to rust and the concrete to spall. Some wear is inevitable, and will hopefully have been designed in for the life of the structure. If wear does become a problem, the surface could perhaps be diamond ground (again, taking into account the cover to the rebar).

    There is not much in the photos that would concern me overly. There is no obvious scaling or crazing/cracking.

    A question: how do they de-ice it in winter? I'm guessing they don't use ordinary road salt due to the problems that can cause reinforced concrete structures in the long term?

    What will probably concern them more is vertical and horizontal alignments, which might be far less visible to the human eye (especially the vertical).