OK. So I'm on my first cycle trip to France. It's 1992 and I'm riding from Bourg d'Oisans to the Col du Lauteret and then to the Galibier. Not long out of Bourg d'Oisans I round a corner and turn into a tunnel not thinking much of it. Suddenly I am plunged into darkness and dis-oriented with only the light from the distant exit for guidance. But there's soon plenty of light, just not the welcome kind, courtesy of the glaring, blinding headlights from an oncoming car. And with it, of course, comes the noise from its motor and tires. And now add another frightening sound, the noise of a truck coming up behind, made deafening as the sound waves bounce around the rock walls. I want to keep off to the side but it's hard since I can't see the side. What's worse I find that simply balancing the bike had become strangely difficult. It's as if I'm balancing the bike by intellect rather than than by instinct. I hit the height of the terror as the truck rumbles by me. I can't tell how close it is or if I dare move over to the right without hitting the wall. Not a fun moment.
Oh yeah. I forget to mention the pavement. The surface outside is fine but the surface inside is scarred with potholes and bad pavement. In my travels this seems to be not uncommon, almost the norm. Another really nasty tunnel at the top of the Marmolada in the Dolomites comes to mind. The pavement was atroscious there - at least in 1994 rode through it, another stop-n-walker.
Lest I put the unfamiliar off too much I should also say that I have a mild case of vertigo which affects my balance and which I believe is the primary source of my particular difficulty in getting through these infernal unlit tunnels. To compound things I'm a bit near sighted and have an astigmatism and wasn't in the habit of wearing my glasses while I rode in 1992. Most folks don't seem to be as negatively affected by these tunnels as I am. Of course I am a bit of a wimp but that aside I'm convinced that what little sense of balance I have is tied in closer to my sense of sight than most folks' and when I can't see I find it difficult to balance. FWIW. I sometimes even have trouble in lit tunnels. Who knows? So if you have any similar ailments or are just a plain old head case like I am you need to get yourself a bike light. I got a NiteRider Digital Headtrip light special for my Y2K France trip and really like it.
In the FYI department, thankfully most of the tunnels on the Bourg d'Oisans to Brianšon stretch have been improved (lit) and there were work crews in a few of them evidently working on further improvements as I drove through during my Y2K France trip. Still I wouldn't recommend the stretch between Bourg d'Oisans and the Col du Lautaret except as a through route, preferably done in the morning or at lunch time when folks are eating and the traffic, I'm told, dies down a tad. Even without the tunnels it's not the greatest for cycling due to the heavy traffic although the scenery is nice. I wish I could say for certain that there are no more of the tunnels left unlit there but I can't remember.
(BTW. The presence of traffic makes the tunnels worse for the reasons I said earlier. Often similar tunnels on back roads aren't as bad because there are no vehicles to compete with. The last time I was in Italy I did an out-and-back ride that went through one relatively short unlit tunnel. On the way out there was less traffic and I got through it without having to walk. On the return trip the traffic was heavy and I lost my nerve and got off and walked.)