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canaljunky

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But not all roving bridges are turnover brideges ( think junctions) nor are all turnover bridges snake bridges (the Southern GU frinstance).

 

The OP bridge is all three though.

PS.   A snake bridge can't be a changeline bridge either because they were built that way so there was no need to do anything with the line

N

Edited by BEngo
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1 hour ago, canaljunky said:

You are all correct - roving bridges are also known as changeline bridges and turnover bridges and snake bridges.

We call them twirly bridges.

Edited by DaveandDebby
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As canals are often/usually built along a hillside, the towpath is usually on the 'lower' side of a canal, looking in cross section. So that when crossing the watershed, the towpath will usually change from one side of the canal to the other, and changeline/turnover bridges often mark where a canal is crossing a watershed. Between East Marton and Barrowford, the L&LC crosses from the Aire into the Ribble, then back into the Aire and then back again into the Ribble watershed, so there are two changeline bridges, below Greenberfield and at Barnoldswick, with Foulridge Tunnel acting as the third.

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39 minutes ago, Pluto said:

As canals are often/usually built along a hillside, the towpath is usually on the 'lower' side of a canal, looking in cross section. So that when crossing the watershed, the towpath will usually change from one side of the canal to the other, and changeline/turnover bridges often mark where a canal is crossing a watershed. Between East Marton and Barrowford, the L&LC crosses from the Aire into the Ribble, then back into the Aire and then back again into the Ribble watershed, so there are two changeline bridges, below Greenberfield and at Barnoldswick, with Foulridge Tunnel acting as the third.

That's really interesting,thank you .

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3 hours ago, canaljunky said:

Thought you might like to see this short vid of us passing under a roving bridge - gives a good idea of how a roving bridge works.  This is Milford Bridge - Bridge 105 on the Staffs & Worcs.  ("Mind your head, woman!!")

 

I was expecting to see a horse drawn boat with the horse going first uner the bridge and then crossing the canal.

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2 hours ago, Machpoint005 said:

Doesn't apply to the snake bridges on the Macc, as the cut doesn't cross a summit! The northern half of it is the summit level.

Yes and no: Pluto was referring to watersheds rather than summits and canals cross minor watersheds quite a lot. As canals are often on sidelong ground can mean the slope being traversed is reversed. 

 

That said I don't think that applies on the Macclesfield 

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I did suggest that there were other reasons for having changeline bridges, but the canal crossing a watershed is not a reason usually considered, despite it being a major factor in determining their use. Other reasons could include the demands of landowners. The L&LC line at Church was changed after agreement with the Petre family at Dunkenhalgh, who insisted that the towpath be on the opposite side to their house to reduce the possibility of poaching etc on their lands. However, the towpath was almost always placed on the 'lower' side of the canal as this kept the land required to a minimum, with the towpath sitting on top of the embankment which retained the water, rather than on additional undisturbed land on the 'upper' side of the canal which would have required purchasing. On long levels, they may have been used to allow some respite for the horse, the load being transferred to the opposite shoulder when the towpath changed sides. Their use on the Macclesfield may also have arisen from this requirement as it is a comparatively late canal, and by the time it was built, the problems in operating with horses, and the associated economics, may have been better understood than on the first generation of canals.

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14 hours ago, system 4-50 said:

This video shows a bridge. It does not show how it works, it just shows a bridge. I also was expecting a horse.

"A horse! a horse! My Kingdom for a horse!"

Or this bridge has been "turned over" and has horses in it. :rolleyes:

 

NLS_Haig_-_Artillery_passing_through_the_Canal_du_Nord_by_a_destroyed_bridge.jpg

Edited by Ray T
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