That song is known as "Berta" by it's rhythm I'd guess & say it's probably a logging or a hoeing song. The reference to marrying a railroad man is only because that's a better choice than a farming man (as in this song) or a convict man as in other songs. Berta, O Berta, Alberta, 18 Hammers, 44 Hammers, Raise'Em Up Higher, has been collected in widely thoughout the southern prison systems, though this version comes from Mississippi State Prison, Parchman Farm. Here are the words as in the show plus some.

Berta, Berta, Oh Lord Gal
Well now

Go ahead & marry don't ya wait on me
Well now (Grunt or Groan)
Go ahead & marry don't ya wait on me
Oh ha
Might not want ya when I go free
Well now
Might not want ya when I go free
Oh ha

Ch: Well now, oh Alberta, Berta, oh lord gal
Well now
Oh alberta, Berta, oh lord gal
Oh ha

Raise 'em up higher let 'em drop on down
Well now
Raise 'em up higher let 'em drop on down
Oh ha
I'm on ol Parchman, got ya, work on lead
Well now
I'm on ol Parchman got ya work on lead
Oh ha

Ch:

Mattie(or Sally or Mary) when you marry don't ya marry farming man
Well now
Every day a Monday hoe hammer in your hand
Oh ha
Mattie when you marry, marry a railroad man
Well now
Every day a Sunday dollar in your hand
Oh ha

Ch:

(verses not sung in the show)

Sit on the cooler let my feet hang down
All she got on is her morning gown

Ol Dollar Mamie told Ol Dollar Bob
Dress that she wanted cost a dollar a yard

Ain't that Berta coming down that road
Look like Berta but she walk to slow

I've been calling Berta the whole day long
How can she hear me when she ain't at home

There's a close version of this on Lomax's Prison Songs vol. 2. The Nex Tradition [Ken & Ally ut of NYC] may also have this version on tape. Not sure it may have been that I recall singing it with them at a workshop.