I think the front around the cab would be a better place to add metal. Construction companies sometimes use large 1" or so thick steel plates to cover holes in streets when they are working on utilities. One of them that is 8’x10’ weighs several tons.
Or simply build the frame from thicker steel to keep the weight better balanced…
So the SD70AH’s are DC powered?
AC.
what does the AH represent in SD70AH ?
A/C traction and heavy frame. If you like letters, it probably should be SD70ACeH
thank you 
When CSX used Dash-8’s as their standard coal power, the normal size train was 90 cars.
When the AC’s became the standard coal power, the normal train sized increased to 100 cars.
With the Heavy AC’s being the standard coal power, the normal train size has become 110 cars.
Each increase in train size has permitted 1000 net tons of additional freight to be moved per train. The revenues from additional tonnage per train mount up.
Appreciated your cla
The heavier weight provides maximum speed on the maximum grade with maximum tonnage. Its purpose is to speed up heavy trains on slow heavy gradient territories.
the real question is what is the point in building any SD70? These are pathetic slippery, painfully noisy droning engines with a solid cab and bouncy make you vomit engines with the isolated cab. Adhesion is a joke, verifiable only in perfect lab conditions. The reality is that they slip and spin and lose speed and stall because the computer won’t let a whiskered hogger apply sand at the right time. Then there’s the obnoxious loud bell warning that the lights will turn off soon followed by the stupid bell ringing warning that the lights actually will turn off now just to make sure you don’t get that desperate safety nap.
Would NS ever dare
They and the SD90MACs will be rebuilt to SD70ACe specifications (whatever that means, there are variations among the units) so there is a possibility. We’ll see what NS ballasts them to.
What is meant by ‘ACe specs’ is that NS will gut the SD90s and rebuild them with ACe internals. The SD80s will get the same treatment (tho they will keep the 20-710) and both will receive new cabs.
Yes. I can’t imagine that the SD90MACs would be ballasted much higher than they are now, considering the fun UP has had with frame cracks.
Surely the ‘refit’ procedure that fixed the frame cracks has enough strength to prevent a reoccurrence!
I’d also suspect that any added ballast would be in the area over or adjacent to the trucks, not in the center or the fuel tank area where it would contribute to frame bending stress. Even slabs applied to the running-board area on both sides should do the trick fairly easily for the amount of ‘weight gain’ involved…
The frame cracks were caused by the weight of the fully loaded fuel tank, which is larger and heavier on the SD90MAC than the SD70MAC, and just four attachment points. If the SD90MACs are ballasted the weight would be spread out over most of the frame.
The Phase 2s have extra bracing bars and plates welded in , no more cracking issues .
I should add that the Phase 2s I know of have the tank continuously seam welded to the frame , not bolted on .
The railroads are using tried and true locomotives. Most of these are rebuilt SD90MACS just upgraded. UP, CP Rail, CN, NS, Rio Tinto, BNSF, and most of the heavy railroads are buying them because they are hauling heady freight over steep passes or heavy coal and ore trains. The SD90MAC and the SD70AH are the same locomotive having one of these up front adds more horsepower with two engines instead of three and burns less fuel this is why they were the first to be upgraded and this is why everyone is buying them.
Perhaps I understand your post completely wrong, but…
To call a SD70ACe a rebuilt SD90MAC seems a wide fetch to me. Different horsepower, different length, different traction motors, different engines (SD70: 2-stroke 710 with 4300 hp up to tier 3, SD90MAC: 4-stroke 256H with 6000 hp), a presumably different construction as crashworthiness requirements were tightened in the meantime.
It was the GE ES44C4 that introduced an AC-locomotive with 4 AC traction motors and an A1A-A1A wheel arrengement to replace ES44DC locomotives in (intermodal) traffic were speed is more essential than traction effort at very low speed.
All these locomotives have just one diesel prime mover.
Currently the only roadswitchers offered by EMD and GE have 4300 hp and 4400 hp respectivly. And from 2015 on they to be certified according to EPA Tier 4. So there is not much choice. Knoxville locomotive Works offers a Tier 4 3200 hp locomotive.
The SD70AH is a SD70ACe ballasted to the allowed axle load for better tractive effort.
There are a number of Tier 4 switchers certified.
If I got something wrong, correct me please.
Regards, Volker