I was hired to complete some alignment layout for H piles and caps on a 1000' railroad bridge. The bridge had a concrete and steel lift span in the center and the project was replacing the old timber pilings and caps with new H piles and concrete caps. When I got started the contractor had already driven the 500' or so of pilings and bents on one side of the river and wanted me to help them with the caps. Long story short they had to do their own best fit layout because they drove the pilings in the wrong place a little bit 6-12" after doing their own layout using a transit and holding the steel/concrete lift span for the starting point. I have pretty limited experience on bridge work like this being mostly highway work with shorter spans, fewer bents, and big abutments where you have some ground you place offset stakes.?ÿ
I was able to set up my total station on some control done by the design firm and stake out the alignment that way. I was wondering if there are any tricks and procedures people could recommend for driving the piling, marking cutoffs and laying out the caps. I was thinking maybe adhesive targets on the piling itself to get it in the right place before its driven? I suggested marking offsets on the timber railroad ties but it sounds like that won't work since they get demolished as the thing is constructed. The contractor wants to mark the cap locations on the piling itself after cutoff. At the end of the day the project manager, foreman and myself will be able to come up with something that works. Just hoping to save some time and headache.?ÿ
After 10 years of working for other people i started my own company this year. I do just about everything by myslef as a one man crew....?ÿ
Wow.?ÿ That's a helluva project for your first 1000' railroad bridge.?ÿ I'm all kinds of anxious just reading that description based on what they did before you got involved.
I'd say go slow as you need to and maybe even wrangle in a specialist with bridge and railroad experience especially.
Hopefully you're getting some reads here and better feedback than I have to offer.
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Keep us posted.
For the cutoffs we would use the base of a magnetic dial indicator to have a solid reference plane to put a mini prism or level rod onto then use a center punch to mark the pile cut off.
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Once you know your required tolerance use Survey Buddy to determine your field procedures/equipment choice to meet them.
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All you need is an old cloth tape. Pull hard as you can to stretch it to the correct reading. Or let is slack depending ?ÿon needed reading. ?ÿLol. ?ÿWhat type of tolerances are needed on a job like that. Seems you don??t have a lot of room for a blunder and not much time to correct either. ?ÿGood luck. Hopefully you will get the answers you need. I have never laid out a railroad bridge before. ?ÿKeep us posted. I enjoy reading on how problems are solved and the after action report of what worked what didn??t what should be done different the next time. ?ÿ?ÿ
Bridge layout is not for the novice.
How did a 1-person firm with zero company experience get picked by a 3rd party with possibly less experience, that already mucked up the job and then hired you to fix it, get a railroad bridge project?
If you??re a licensed professional, I hope your insurance coverage is off the chart for trying to push/sell an app to the general public that may result in safety concerns.
This entire thread is a great example why licensing, experience, and insurance exists.
I hope nobody gets hurt.
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Bridge layout is not for the novice.
How did a 1-person firm with zero company experience get picked by a 3rd party with possibly less experience, that already mucked up the job and then hired you to fix it, get a railroad bridge project?
If you??re a licensed professional, I hope your insurance coverage is off the chart for trying to push/sell an app to the general public that may result in safety concerns.
This entire thread is a great example why licensing, experience, and insurance exists.
I hope nobody gets hurt.
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I'm confused, exactly where did I try to sell anything? Please also point out the safety concerns of error propagation formulas??ÿ
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I've put hundreds of hours into Survey Buddy and am offering it 100% free as a learning tool. The equations used are correct and nowhere is there any guarantee of any precision. It's all within confidence intervals and clearly states that systematic errors need to be accounted for.
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Your post is a great example of shitting on people trying to help without offering any advice what so ever.
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Once you know your required tolerance use Survey Buddy to determine your field procedures/equipment choice to meet them.
It's called product liability.
It's why McDonald's has to label their coffee is hot.
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Here's my unsolicited advice that may cause you to reconsider the "$h!tt!ng" comment:
If you are a licensed professional and have "professional liability" insurance, it probably doesn't cover "product liability". Maybe it does, but I would think you may want to ask, since you seem to be in the app/software business too.
@bc-surveyor Where can I find this Survey Buddy app? I tried www.The3rdDimension.net and couldn't find it there, or in the google play store.
@bc-surveyor Where can I find this Survey Buddy app? I tried www.The3rdDimension.net and couldn't find it there, or in the google play store.
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Hey Ramses,
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There is a download link in the description of the video. Ill attach it here as well.
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Hi Andy,?ÿ
As a professional surveyor I have layed out many R.R.bridges across the country for Union Pacific & BNSF. Here is a few of my thoughts,
Run horizontal control from one abutment to the other and verify the designers provided control and the designers provided alignment matches the existing alignment. If it??s off minimally you can adjust, if off alot send out a RFI.
Run a closed level loop from one abutment to the next and establish good vertical control along the way off of their project provided control.
Read the contract specs for pile layout tolerances, normally the top of pile cutoff location has a circle diameter tolerance of 1-1/2?, which means that cl-pile cannot deviate outside of that circle or the pile would be rejected. I have seen some circle tolerances as large as 3? and as small as a 1/2?. Read the specs and plans.
I would expect these piles are simple battered piles at 1:12 or 1:20 or something, (hopefully they are not compound battered piles.) Always lay out the battered pile location on the ground, for example if your cutoff is above the ground 30ft on a 1:12 batter you know you have to adjust outward and away from the design location 2-1/2?? at that specific ground location. Some pile crews will ask for the design location and they try to adjust the batter to the ground and it always ends really screwed up. I would guess this may be why some of the piles are off as you mentioned in your post. Hopefully the pile crew will be using some sort of pile templet to get the pile started in the ground at your layout point in he right position.
For the pile cutoffs I have always leveled to the pile from good vertical control and marked the c.o. elevation all the way around the pile, I would not use a total station or targets, I think you need to be as tight as possible here marking these cutoffs, think about it?? if it??s off and cut to low your going to have major issues, sometimes they will allow you to add a splice to the pile.. other times I have seen them totally reject the pile and you have to pull it and reset.(not good)
Once the piles are cut and are within tolerance most designs require a steel plate to be welded on top of piles, you will mark you centerline of bents and centerline of track alignment on top of these plates. On the precast bent caps there will most likely be another steel plate embedded into the bottom of concrete precast bent structure, you will also need to mark the centerlines of these structures on the ground so when the crane pics them it??s just a matter of aligning the both centerlines to get it close. Once the cap is sitting on the plates set your total station up and dial the bent cap in as tight as you need, check the top of cap and bottom of cap,( they are not all poured the same). As the caps are set verify the location and elevations on top so than your span between bents are correct, the last thing you don??t want is the cross beams coming in that doesn??t fit between bents.
The last thing I would say is ??document control?, make sure that you have everything and everything recorded, every layout, elevation, control point, asbuilt elevation, cutoff elevation, rod height??everything. In heavy construction everyone is nice and friendly until there is a F.U. Then everybody starts blaming because that??s how human nature is?? if you have all your documents in place you??ll be able to eliminate 99% of the BS.
The contractor called you because they realize they have a major problem and they need help, read and know those plans and specs inside an out, do it right and don??t take shortcuts, the rail company??s will not accept sub standard work. If you resolve this problem for this contractor I assure you they will call you every time??
best of luck??
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If you resolve this problem for this contractor I assure you they will call you every time??
I agree, One time a contractor called us to do some layout for a town job because it was in the contract/budget. We showed up and staked everything they wanted. Next thing we know they started calling us for pretty much all their jobs. Said it saved them time and money to just have us do it.?ÿ
Here is a few of my thoughts,
I think your post was one of the best that could be made.?ÿ
My construction boss in Chicago always said ??know your tolerances?. And, often those tolerances are very different in the station, vs offset, and elevation.?ÿ
For example, a catch basin could be 10?? off in station, but not in Rt Lt offset, and often the elevation would have to be changed, due to the change in stationing.?ÿ
Or a freeway exit could stand a larger radius, but a shorter one could cause trucks to tip over, at a rated speed. Or, other problems due to icy roads.?ÿ
I??d have to agree 100% with the ??study the plans? comment above. Sometimes numbers change on updated plans. Be prepared to alert the super to significant changes.?ÿ
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@jms66?ÿ
I planned to run a level loop down the bridge from the one project vertical benchmark on top of one of the abutments. The batter piles are 1.5:12 and they have some sort of templet made, haven't seen it... The precast caps have a steel plate cast into the base, that's what gets welded to the H piles. After cutoff i will mark the alignment sta/offset on the H pile flanges for alignment of the cap... REAL PITA to mark that way... AS far as precision goes i am going to mark everything perfect, like .02' that way if its off it's all on them.... It's a low speed section of track, the contractor told me there is three layers of adjustment they have too in case things are off. THey can adjust the cap position relative to the piles, ballast, and then the rails. Thats how they were able to make it work when they drove the first batch of piles all over the place...?ÿ
Thanks for the good information, I appreciate it.?ÿ
@jms66?ÿ
...the contractor told me there is three layers of adjustment they have too in case things are off. THey can adjust the cap position relative to the piles, ballast, and then the rails. Thats how they were able to make it work when they drove the first batch of piles all over the place...?ÿ
From my very limited exposure to piling and adjacent works, that sounds very hard to believe. I would still try to get some hard numbers on how much they can adjust and get it in writing. A pile is a hell of a thing to fix, especially after it's been poured.
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