i am just guessing here, but i always thought is was about life on the road with a band, too much drugs and cheap sex. i think it is about doing groupies that you know you shouldn't while you got a wife/girlfriend back home, but you do it anyway because of impaired judgement and feelings of invincibility brought on by the coke. before you deadheads splutter your organic coffee all over the computer screen, think about it. train has been used as a metaphor for, um, a man's junk, for ages.
so look at it from that perspective, ageing rock star thinking i am getting too old for this s##t! here i am again, couldn't say no to the lady in red.
this 'old' engine, makes it on time? (i know jerry was young then compared to most of you readers, but life on the road does leave you feeling ancient even in your mid twenties!) quarter to ten it's rolling again? (with the coke yer engine will just not stay down!) watch your speed (jackrabbit coke fuelled sex)trouble ahead, lady in red? (the groupie) trouble behind (the wife/gf). notion just crossed my mind (sudden realisation while in the act, oh no, i f**ked up again!) trouble with you is the trouble with me (commiserating with bandmates, why can't i stop when i know i should) and finally, come round the bend, you know it's the end, fireman screams and the 'engine' just gleams???? c'mon people, if this ain't a metaphor for climaxing i don't know what is!!!
ok, so maybe i have a twisted mind, but it makes me chuckle to think of it this way. it suits my experiences and resonates with me so even if that was not the original intent i always think of it this way. and here's the thing, now that you have read this you will not be able to listen to the song again without seeing the image of jerry flailing away with some groupie thinking 'damn, i am too old for this....hmmmm, good idea for a song!'
peace and love and a bit of laughter i hope. no offence intended!