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Weathering steel bridges
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As a general guide bridges received high priority for maintenance...'cos it cost a fortune if it fell apart. <br /> <br />A sign of a dieing line / very hard times was a bridge in a bad state. <br /> <br />The floor of a deck bridge here (UK) would normally be weathered bitumen... which is (basically) black/brown or brown/black. Sometimes the coating had a weird mid grey/silverish look... this tended to have brown/black lines or patches. Deck coating (usually) spread 6 to 9 inches up the metal sides and fittings. Timber waybeams would be tie colour...'cos they'd be treated the same. <br /> <br />All the rules of weathering track apply... what's happened since it was new? How well has it been maintained? Has anything been renewed/replaced? Has it been cleaned... in this case cleaning means removing leaves and litter which otherwise build up in corners (just like in a garden)... you can get bits of tree, dead fox, dead cat, bits of load fallen from cars (from sand to pallet material... grain could start to grow in the leaf litter) All this should be cleaned out by the MoW because anything rotting will damage the coating, let in water and damage the bridge structure... then the cost rockets. <br /> <br />[We had a double track bridge (rail over road) lifted out by an <i><b>enormous </b></i>road crane {this thing was so huge that they dug out the bank on each side on put in concrete plinths for its feet to stand on - the tyres were about 10' diameter - it came all the way from Italy} ... old bridge was cut up and removed, new bridge lifted in... they just had to make the last adjustment and the crane conked out... That was Saturday morning. It took all of Saturday to find the engineer/fitter - who was on holiday in Spain, fly him back to Germany to get his tools then bring him to London. Five minutes in the machine and he came out with a bust O ring about wedding band size. "Here's the problem". So by Sunday tea time they'd located a replacement and had it on the way from Sweden. All this time everything is just standing. One of our British Rail guys wandered out to get fish and chips... as he came back one of the spectators asked him "What's the problem"? "**** bridge doesn't fit"! So next day in the newspaper... <br /> <br />Anyway, back at weathering bridges... you'll get graffitti as well... even on the deck... strange places football fans write things... <br /> <br />You may get waybeams replaced with new coating patching them in. Or just patches in the coating. <br /> <br />In many ways the bitumen coating on a bridge is like the bitumen coating you get on some flat roofs. <br /> <br />In steam days leaves would be removed before they could dry but fire water tubs would be provided as well in many cases so that hot ash or a spark would not start a fire which would ignite the bitumen... suggest you look out for details such as tubs in old photos. <br /> <br /> <br />Next post (below) makes a lot of good points. Especially about the paint crew. If I ever get that far I will have signs of a bridge being re-painted - this happens in snatches of time between traffic. repainting involves cleaning, scraping (blasting sometimes), (repairing), priming and several coats of paint... sometimes the graffitti people get in before the work is completed... the work can't be signed off until the whole bridge is clean and new so (if it persists) the RR police get involved... it's amazing how much a K9 looks like it's grinning when it has a lump of pants' cloth in its jaws... <br /> <br />The sides of a steel bridge (inside and out) will weather in all the same ways as a boxcar or gondola... but shouldn't have the dents. <br /> <br />In urban areas there is a huge problem with pigeons roosting under bridges this leaves streaks on the structure and lines of guano on the road or rail below in pairs matching the underside of the beams in the bridge (pairs because they roost both sides of I beams). It is a health hazard... you can also get pigeon mites which bite worse than cat fleas - fortunatley (for me) they prefer females for some reason... we had ladies put off sick because of the evil things. <br /> <br />Have you thought... if you have any cable ducting for phones, signal/point control or whatever or pipework it has to be carried over or under the bridge... look at pics again... <br /> <br />Small (1 gal to 5gal) tubs of maintenance material and tools aren't supposed to be left on bridges but they often are. <br /> <br />Modern era maintenance would often get a portable office and/or a 20' container (or2) parked close by. <br /> <br />Where a road goes under you do sometimes get a dent where a high truck has hit the bridge... but it isn't that big... (a) because the truck loses and (b) because only a small amount of damage can be allowed. You also get scrapes... to the supports as well as to the underside. Bridges are pretty good at removing the load from the top deck of car transporters... <br /> <br />Talking of the supports... If they're brick you get all the weathering associated with buildings... similar for stone and concrete. You get a lot more streaks from water outflow both where it's meant to flow from drains (look for these in pics) and where it seaps and runs. If the air is clean these stains can have moss and ferns growing. You even get small trees starting to grow (they're not supposed to be left to get big). Ivy is frequently a major feature... it's amazing where plants will grow... especially ivy. <br /> <br />Two things associated more with brick retaining walls (than with concrete or stone) are cracks and repairs. Both in bridgework and buildings you can often cracks either following the mortar lines or straight through everything. You can also see new brickwork inserted to repair cracks or just re-pointing to strengthen existing masonry. <br /> <br />The size of cracks in abutments is sometimes surprising. Large areas of masonry can be displaced an inch or so. The critical thing is that the structure settles in a stable position. The engineers often put on various markers to help them monitor the movement of cracks/structures. <br /> <br />While a sidewalk under a bridge may be swept there is often a band of traffic splatter up to 2' up supporting walls on both sides of a road. Under bridges is also a common place for puddles even when there are drain grids. <br /> <br />Manholes (for sewers/drains/telecoms) don't usually come under bridges... but are often close to the approach... also telecom location boxes. <br /> <br />Street lights are often fixed to the bridge support instead of on poles... if the bridge is long they may be on 24/7 <br /> <br />There are of course all sorts of road signs associated with bridges - especailly height limit warnings and red/white or yellow /black stripes on both supports and bridge beams. (And people still hit them). <br /> <br />Has this answered the question? [8D] <br /> <br />Going back to the start the reason for bridge maintenance being high priority isn't just that a bridge out shuts the line but it may also shut whatever it is crossing/crossed by with compensation costs. Also a wreck at a bridge is almost always a bad wreck. <br /> <br />Have fun!
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