There's a version in the Max Hunter Folk Song Collection,

http://maxhunter.missouristate.edu/

with links to audio files and a transcription:-

The Longest Train

The Longest Train I Ever Saw
Cat. #1122 (MFH #780) - As sung by Ollie Gilbert, Mountain View, Arkansas on April 9, 1970

VERSE 1
The longest train I ever saw
Run by Joe Brown's coal mine
The headlight passed at six o'clock
The cab came by at nine

VERSE 2
The prettiest girl I ever saw
Is on that train an' gone
Her eyes were blue, her cheeks was brown
An' her hair is hung way down

VERSE 3
Th train it wrecked at four miles
It killed my Evalane
Her head was found in th driver's seat
Her poor body hain't been found

VERSE 4
Th longest way, th longest day
The longest night
Was th day Evalane died

VERSE 5
I walked th track
Whole day alone
I bowed my head an' cried

VERSE 6
Th long steel rail, the short cross ties
They carried away
The arms that brought me safely here
But I'll make it home, someday

I find it sings better if you join up verses 4 & 5 above. I think I've also interpolated bits from somewhere else (not sure where?) to get what I sing (below).

The Longest Train I Ever Saw

The longest train I ever saw
Run by Joe Brown's coal mine;
The headlight passed about six o'clock,
The caboose came by about nine.

The prettiest girl I ever saw
Is on that train and gone;
Her eyes were blue, her cheeks were brown,
An' her hair hung down so long.

The train it wrecked about four miles out,
It killed my Evalane;
Her head was found in the driver's seat,
Her poor body ain't never been found.

The longest day, and the longest night
Was the day my Evalane died;
I walked the track the whole day alone,
An I bowed my head an' cried.

Those long steel rails, and those short cross ties
Have carried away
The arms that brought me safely here,
But I'll make it home someday.

The longest train I ever saw
Run by Joe Brown's coal mine;
The engine passed about six o'clock,
The caboose came by about nine.


In The Pines (also in the Max Hunter Collection) has a verse beginning "The longest train", but mentions the "Mason line" as the location.

Ross