Field superintendent in Austin told me my grade beam layout was off by 3/8 of an inch on a 200 foot run

I was using a basic transit level like I always do on smaller commercial jobs. He pulled out a robotic total station and showed me how the error compounded over distance because I wasn't accounting for temperature expansion on the tape. Now I always use a laser measuring tool with temperature compensation on anything over 100 feet. Has anyone else run into this issue with long spans and standard tape measures?

2 comments

2 Comments

oliviat171mo ago

Gotta admit, I learned this exact same lesson the hard way on a parking lot layout. Pulled my hair out for two days before an old surveyor told me about steel tape stretching and temperature. Now I only use a standard tape for anything under maybe 80 feet and switch to a laser or a properly calibrated EDM for longer spans. It really does make a difference, especially when your error just keeps growing down the line. You think most guys even know about thermal expansion on their tapes or do they just assume it's close enough?

margaret3041mo ago

Are you using a fiberglass tape or steel for the shorter stuff? @oliviat17 I've seen guys pull out a hundred-foot steel tape on a hot day and wonder why they're off by half an inch, so yeah, most people really don't think about it until they're already fighting their own numbers.