And hope the bridge steel fabricator knows what SPC with CSF means, too, or somebody does the translation to true length at specified temperature for them.
Even if you do it right you will get sued when the parts don't fit.
In the absence of evidence to the contrary it would be fair to assume that everyone from the design engineer to the steel fabricator will not account for the scale factor so you will need to convert your grid coordinates to ground and work in that. (as described above). The difference can be lost in the road construction either side of the bridge.
If it's a series of bridges and if there are other contracts/surveyors then it could be more complicated.
Make sure you issue queries or emails to that effect and be prepared to have to explain the whole thing
That said, 5.7mm in 100m is bugger all and unlikely to ever be noticed.
Round here it's 40mm in every 100m.
Interesting post and replies. I've been around bridge engineers for a long time. The last thing they would do is design a bridge and quantify bridge parts on any scale but 1.?ÿ I would think long and hard before staking out a bridge on any other scale.?ÿ As others have pointed out your total length difference between grid and ground is 3/4".?ÿ Where you could get off is where the center of the bridge is supposed to be without considering the scale from a distant control point. After you figure out where the bridge belongs any scale other than 1 is fools play I say.?ÿ
In the absence of evidence to the contrary it would be fair to assume that everyone from the design engineer to the steel fabricator will not account for the scale factor so you will need to convert your grid coordinates to ground and work in that. (as described above). The difference can be lost in the road construction either side of the bridge.
If it's a series of bridges and if there are other contracts/surveyors then it could be more complicated.
Make sure you issue queries or emails to that effect and be prepared to have to explain the whole thing
That said, 5.7mm in 100m is bugger all and unlikely to ever be noticed.
Round here it's 40mm in every 100m.
Sorry, to be clear you don't need to "convert" your setting-out co-ordinates, just use them as ground co-ordinates so they tie up with the length of the bridge.
You will need to convert your control points by from scaling from the centre of the bridge (or one end depending on where you want to lose the discrepancy).
Use these control point co-ordinates for setting out the bridge, the distances between them should have a scale factor of 1.
?ÿ
