The problems of accuracy of linear measurements at the accident place presented at a conference organised by Institute of Forensic Science in 2006 aroused considerable interest. Since the issue is important the authors have decided to compare and tabulate the results of measurements of the same values taken with different measuring instruments: popular single and double roller wheels, of various diameters, measuring tapes, laser instruments, etc.
The differences obtained in measurements taken on uneven surfaces, covered with sand, mud or little stones of various granulation seem to be particularly important. In the article, besides the tabulated results, the causes of errors and their predicted values have been suggested.