Given current accuracy of the techniques, is it possible to identify a real, existing tunnel (stright I think) to make the direct comparison of the speed of light and of neutrinos? The hypotetical tunnel from CERN to OPERA would-be too long. If we were able to increase accuracies by two decades, then would a 7.3 Km tunnel suffice ? The 60ns difference would become around 600ps. Suppose there is such a tunnel, suppose it can be availabe to physicists. Apart from all the logistics problems of generating and detecting light and neutrinos at the two ends of such tunnel, are there other difficulties?
Unlike neutrinos, light will be slowed down by gas in the tunnel, which would have to go through the Earth. It is much cheaper and easier to mathematically analyze the OPERA results to find their error, were they ever to release their detailed protocol, which is unlikely, because they don't seem to want the error discovered.