Regular user of the TT route here. Lighting is just fine, low-level, but enough to see clearly. One can however see for very long distances ahead on some stretches, and having 'be-seen-by' lights, (as opposed to death lasers) is a courtesy as it allows people to see you earlier - an unlit user can blend into the shadows until a few dozen yards away. More psychological security than strictly necessary. Us locals are doing a good job of discouraging the scrotes. This is a fairly busy route, and anyone engaging in anti-social activity is going to be conspicuous. There are inevitable problems with idiots as everywhere, including some hog-whimperingly stupid types who thought riding horses in there might be a wheeze - but these are very exceptional and swiftly dealt with - 'tutting' echoes well and sounds much more intimidating :-) Speeding is an occasional issue, but the TT route is not special in this respect. I myself have shouted in an ungentlemanly fashion at members of a local cycle club on the Bath Bristol path. "I bet you drive your car like that too!" is my favourite lame riposte to cut-ups etc, sad really at my age . . .