Boy, what a can of worms.
But, back in the old days, before there were guaranteed extra boards, the unions regulated the boards. Every week, the carrier supplied the appropriate union officer (usually the local chairman) the mileage figures for the extra boards. All the extra board mileage was totaled, divided by the number of employees on the board and the board was adjusted accordingly. Extra board mileage back then was 3200 to 3800 per month (or 741 to 880 per week). If the average extra board turn worked less than 741 miles per week, they cut the board. Back then, the basic day was 100 miles for everything. Engineers were supposed to turn in "mileage slips" to aid in computing mileage (they'd hold you out if you didn't turn in your mileage slips.). The clerks kept track of trainmen mileage (I think). Everything was figured in; overtime, extra mileage, extra payments. If the average mileage dropped below the minimum, the men demanded the board be cut. Obviously, two issues were at play. One was that it was a cut-throat procedure. The other was that the board was being regulated next week according to what happened the week before.
My carrier (CSX) still keeps track of mileage, both pool and extra board. We still adjust pools according to mileage agreements. The carrier obviously still uses some formula to adjust the number of men on the extra boards, whether its mileage or days or starts.
Just as an added idea or thought: The old UTU Fireman's agreement had a guaranteed extra board that called for 6 starts per week. If you made less than 6 starts, then you were entitled to a minimum days pay at hostler's rate of pay for each day you didn't work up to (i.e. If you only made 4 starts, you were entitled to 2 days pay.). Each trip counted as a basic day, no matter how much you earned on that trip.
The thing about mileage is that some want to work as little as possible, some want to work as much as they can. You can never satisfy both sides.
good luck!
