I've been in the train tunnel on numerous occasions, the last time about 25 years ago. It's been modifed since. There used to be 2 tubes active and now, I believe, one is inactive. The tunnel, in spite of it's last modifications, is still too small for the latest train cars. The result is Detroit's lost traffic to the new Port Huron Tunnel. I had friends who worked for the railroads and we'd go 'high railing'. They had pick ups with train wheels which you'd lower to meet the tracks. Once you got clearance from a 'tower', you'd take off on the tracks. We went in the tunnel on many occasions but never came out 'fully' on the Windsor side because we never had an okay from Customs/Immigration. I have photos, not very clear or descriptive, of the tunnel. I'll post one if I can find it. We'd meet up at one of the railroaders hang outs, like Mike's Famous Ham Place on Michigan Avenue near West Grand Boulevard, early in the AM, eat breakfast, load up on coffee and head out to ride rails, mostly on weekends. It was lot's of fun. We rode most of the major tracks around downriver, the west side and up to Hamtown.