Pre formed concrete panels.

[Fubar]

Got a bridge 12m long and 5 m wide made up of 2 rows of wooden sleepers lay across 3 large carrying girders (1 in the middle and 1 on each side) . Been there 30 odd years and the sleepers are starting to rot now so it needs a major repair. There are 90 sleepers in total. To replace them all with grade A would cost around £2700. I've had a quote of 5k + vat to board the gaps and pour 8 inches of reinforced concrete across the lot for what I'm told will carry upwards of 40 t.
Trouble is I can't really afford to leave it for the several required weeks for the concrete to set properly as i need regular access yo the land.Would 8 or 10 inch pre cast, reinforced concrete panels that are used for walling be strong enough. I could buy 8 1.5 m high × 5 m long ones and lay them crossways, butting them up and fixing them together.
Trouble is the gap between the outer girders and inner girder is 5 ft and it is in the middle of this gap that the tractor wheels run thus putting the most weight in the weakest part of the bridge.

 

[Courier]

Would need panels specially designed for the loading when used as a supporting surface. I doubt that walling panels would do that as the loadings would be different - a good panel manufacturer would be able to incorporate reinforcing to your requirements though but whether he would be able to certify them for insurance is another matter.

 

[Lakesdigger]

Are the steels strong enough to carry the weight of a concrete deck be it panels or cast in situ plus a vehicle driving across. You'll be looking in the region of 35 ton before you even drive on it.

 

[Tarw Coch]

Stuart Jones of Jones brothers told me he’d done some panels for a bridge a few years ago, iirc he said made to a spec from a structural engineer.

Panels or poured concrete are going to be heavier than sleepers, is the steelwork going to be up to the extra weight?

 

[Fubar]

The steels are massive. Should certainly take the weight of concrete plus any vehicles. Actually intending to pour 250 mm of high strength concrete plus 2 layers of mesh so I guess that's as strong as I need. Would be nice if the bridge could be a bit narrower but the angle of approach means anything narrower would make crossing a bit more risky.

 

[roscoe erf]

I’d stick with the original design £2700 seems cheap for a crossing divide that by 30 even cheaper

 

[Tarw Coch]

I’m curious how big the drop is.
As a young lad working for a contractor I used to lug silage across a bridge topped with sleepers that weren’t the best. One day when I got to the farm the farmer asked me to give him a hand to replace a couple of rotten sleepers and I remember thinking a couple, they all want replacing !
The main steels were massive, about 4 foot deep with other steels of about 2 foot looking small in comparison.
However the span was at least 60 feet with a drop in excess of 20 feet, big enough to swallow a tractor and trailer whole if something did go wrong, it was quite unnerving watching the sleepers move as you crossed especially as there were a few that as I say were far from the best.

Edit : they were actually crossing timbers , much longer than sleepers

 

[Tarw Coch]

I’d stick with the original design £2700 seems cheap for a crossing divide that by 30 even cheaper

In comparison to the value of machinery passing over even cheaper still

 

[Fubar]

2700 over 30 year life span does seem reasonable. Just concerned that kit is getting heavier. 30 years ago it would have been max of 15 t crossing it. Although most of the sleepers are only 9 inch. I guess the thicker grade A s would be better.
It's not actually my bridge. It belongs to someone I do contracting for and he's asked if I can repair the bridge. So it's not really my problem or expense, although it's my kit that has to cross it . Smallish river about 10 ft or so down. Certainly don't want to end up in it.
My initial thoughts were to just replace the sleepers but whenever I have enquired to locals about fixing it they had said to pour concrete as it will be stronger and last for ever.

 

[Ffermer Bach]

how about concrete sleepers?

 

[Fubar]

how about concrete sleepers?

Did think that but they don't sit all that evenly and can also crack

 

[Tarw Coch]

Regarding pouring concrete being stronger, I’m not so sure.
If there’s any flex at all in the steels concrete could crack whereas flex with sleepers wouldn’t matter

 

[Fubar]

Might be heading down the 10 × 6 wooden sleepers road. Simpler, cheaper, less risk and if they last as long as the last lot then that will do me.

 

[Courier]

Might be heading down the 10 × 6 wooden sleepers road. Simpler, cheaper, less risk and if they last as long as the last lot then that will do me.

If you are concerned about future weight increases you could always use them on edge
With maybe a 2” gap between to promote ventilation and drainage to prevent long term rot.

 

[Forever Fendt]

I have some big steel beams in excellent condition 11m long at sensible money should anyone need to build a crossing

 

[Sparkymark]

I used concrete railway sleepers to replace my wooden ones, they sit just fine

 

[newhollandfarmer]

Got a bridge 12m long and 5 m wide made up of 2 rows of wooden sleepers lay across 3 large carrying girders (1 in the middle and 1 on each side) . Been there 30 odd years and the sleepers are starting to rot now so it needs a major repair. There are 90 sleepers in total. To replace them all with grade A would cost around £2700. I've had a quote of 5k + vat to board the gaps and pour 8 inches of reinforced concrete across the lot for what I'm told will carry upwards of 40 t.
Trouble is I can't really afford to leave it for the several required weeks for the concrete to set properly as i need regular access yo the land.Would 8 or 10 inch pre cast, reinforced concrete panels that are used for walling be strong enough. I could buy 8 1.5 m high × 5 m long ones and lay them crossways, butting them up and fixing them together.
Trouble is the gap between the outer girders and inner girder is 5 ft and it is in the middle of this gap that the tractor wheels run thus putting the most weight in the weakest part of the bridge.

I can tell you now without getting my calculator out that 8 inches is nowhere near thick enough to support the impoosed load of 40 Ton considering on the tension side its only supported at 2.5m intervals. Unless they are planning on bracing the original steelwork massively and will provide data of their design/performance figures with an indipendent chartered engineers report I wouldn't hand over any cash. Sounds really retentive but that's where we are now days, if someone was to get hurt as a resultant failure your in trouble with the man in the wig as it all lies on you.