The evidence of your own eyes. Irrelevant?

[Martin Cassini]

There is a tendency among traffic engineers to dismiss eye witness accounts as anecdotal evidence, and direct experience as irrelevant. If it can't be counted, it doesn't count. If it can't be weighed or measured, it doesn't exist. A remark overheard at a traffic management meeting seems to sum it up. "Our traffic systems would work fine if it weren't for the problem of pedestrians."