Who told you one cannot use his legs to measure a distance on a site? This is a standard surveying technique called pacing.
In civil engineering and site reconnaissance, pacing is a recognized way to get a quick estimate of distance. Every experienced field engineer knows their average stride length. You walk the alignment, count your steps, and multiply by your pace factor to get the rough dimensions.
It is not meant for final structural models or detailed design, but it is perfect for on-the-spot field assessments. You do not need to pull out a measuring tape just to get a preliminary feel of the road width or drainage length.
Many of you just laugh at things you do not comprehend.
Crazy thing I saw today:
Professor of Infrastructure David Umahi measuring the roadside with his legs. I still wonder why this country is not a Netflix series!