I've used and been witness to using power hammers to do spike driving and they do have their benefits and drawbacks.
One big drawback (and you can see it in the picture provided) is that you need a pilot hole for every spike or you need them the be pre-set in the tie by somebody with a maul. You can't start them with the power hammer.
You wouldn't want to start a spike with a power hammer. Either drill a starter hole or hand-set with a hammer.
Another drawback is that you're more prone to bending spikes beyond recovery. Hand hammering is just as likely to bend the spike, but you can stop and bend it back out mid drive. With the power hammer you're liable to not notice it until it's too late. The possibility of bent spikes goes up if you're using smaller spikes than you see on 3' and standard gauge lines.
You would want to have more experienced people run and manage the power hammers. You don't want to go willy-nilly thinking you're superman just because you have a power hammer.
With the pine ties it seems easy enough to drive spikes that I bet the gangs will have no major problems putting down 300-500 feet a day. That's 150-250 ties and 600-1000 spikes. 800 ties and 3200 spikes in a weekend is a big order, but doable based on what has been done in the past. I believe the record years they were doing it with oak ties and no pilot holes, which from my experience in Portland I can tell you is no fun.
Thus the point of a power hammer. Work smarter, not harder.
Let's model with two hammers using your numbers of spikes. (70/day * 2 hammer *3 days = $420) with a gang of 4-6 to run the power hammers
3200 spikes = 1600 spikes per power hammer, 13 cents per spike driven
Assume with 24 hours of work over 4 work days and you get and average of 50 spikes per hammer-hour (25% inefficiency over an 8 hour day)
1000 spikes = 500 spikes per power hammer, 42 cents per spike driven
Assume with 24 hours of work over 4 work days and you get and average of 16 spikes per hammer-hour (25% inefficiency over an 8 hour day)
It's linear, but let's run the number with 4 power hammers (70/day * 4 hammer *3 days = $840) with a gang of 8-10 to run the power hammers
3200 spikes = 800 spikes per power hammer, 26 cent per spike driven
Assume with 24 hours of work over 4 work days and you get and average of 25 spikes per hammer-hour (25% inefficiency over an 8 hour day)
1000 spikes = 500 spikes per power hammer, 84 cents per spike driven
Assume with 24 hours of work over 4 work days and you get and average of 8 spikes per hammer-hour (25% inefficiency over an 8 hour day)
Turnout is never predictable but with how much it's been known that "new iron" is going down my understanding is that turnout is up, especially with the younger demographic. I believe Joe's spring tie replacement group had at least 8 guys under the age of 25. That's not the 100+ that have mobbed the fall work weekends in the past, but 75 or so replacements plus the wholesale track section replacement in 4 days is testament that even a small crew can get a lot done with the current materials.
You are assuming that the availability of "under 25 years olds" is perfectly elastic, I'm betting that it is inelastic and Joe's pool of potential support is nearly tapped out.
The museum is already seeing a Year-over-year reduction in labor. There is a reason why the temporary bridge is designed for a second life in MOW service for laying rail.
Nothing prevents a section being hand-layed. The spikes can be hand-started if people want to do that. I'm just saying that the prior model of hand laying track is unsustainable.
My understanding is that we only want a maximum of 1600 feet this year anyways because the contractors are going to be accessing the roadbed from right next to where that 1600 feet stops. Equipment and additional materials and whatnot are going to come in through there instead of going over the bridge to reach the areas between the future EOT and the bridge site.
I believe Mike has said that location 10 and 11 might get completed prior to FWW since the contractor wants to complete most activities on the south side this year. It is all going to hinge on the completion of the pinch point so Contractor Jeff can get to the rest of the south side with his equipment to place the bridge.
Contractor Jeff wants to haul the material in from the access road, versus across the bridge next year. So this moves up our culvert installation to this year.. Contractor Jeff will help so we can do it quicker.
