This is done by putting a series of nails in the pavement, leaving the heads protruding a bit. You hook your tape over the first one and measure to the second and record the measurement. Then you walk back, unhook the tape from the nail, and drag it far enough to hook it on the second nail. You hook it on and measure to the third nail. Proceed until you have enough length for a calibration course. When you are done you add up all the segments. Be sure you account for the offset between the center of the hook-on nail and the zero point of the tape. The offset will apply to each segment.
The first time I did this I went through the procedure from one end to the other. Then I did it in reverse order. There was a lot of walking back and forth.
It struck me that if I simply read the tape twice, this would count as two measurements. However, I have had enough misreadings to not trust this. It’s easy to get the same wrong reading twice.
Yesterday I tried a different approach. I have a tape that is 100 feet on one edge and 30 meters on the other. I put nails in just shy of 100 feet with a limp tape. Then I stretched it and read the metric value. Then I read the feet/inches. I believe this qualifies as two measurements.
I recorded the tare (amount to be deducted) as ¼ inch and also 5 mm.
Below is how the data looked.
