I have no insight into what assignments these units will receive on BNSF. However, as I indicated in my 1-27 posting, a design concept behind these units is that a four-motor AC-traction unit can be a viable alternative to a six-motor DC-traction unit.
My frame of reference for locomotive-testing scenarios is the program that GE and CSXT conducted in an effort to maximize the tractive effort of six-motor 4400-hp AC-traction units; and I believe that the aspect of that program that's most relevant to the current GE and BNSF program is its duration. The time period between GE's construction of the first prototype test unit and CSXT's decision to increase the tonnage ratings of the production units was five years and nine months. And an additional two years elaped between then and when the modifications were applied to preexisting standard units. During this time, unit performance in a variety of operating environments was monitored, units were modified, additional monitoring was done, and so forth.
My point is that I don't believe that anyone will know exactly how the BNSF units will perform until they are placed in service. I'm sure that GE has performance expectations based on certain weight distributions and speeds. However based on the prior CSXT testing program, it would greatly surprise me if the BNSF units were placed into service and shortly thereafter the two-unpowered-axles concept was declared either a success or a failure. My expectation is that there will be a lengthy period of time during which the units are modified in a variety of ways and that these modifications will result in significant performance changes.
My frame of reference for locomotive-testing scenarios is the program that GE and CSXT conducted in an effort to maximize the tractive effort of six-motor 4400-hp AC-traction units; and I believe that the aspect of that program that's most relevant to the current GE and BNSF program is its duration. The time period between GE's construction of the first prototype test unit and CSXT's decision to increase the tonnage ratings of the production units was five years and nine months. And an additional two years elaped between then and when the modifications were applied to preexisting standard units. During this time, unit performance in a variety of operating environments was monitored, units were modified, additional monitoring was done, and so forth.
My point is that I don't believe that anyone will know exactly how the BNSF units will perform until they are placed in service. I'm sure that GE has performance expectations based on certain weight distributions and speeds. However based on the prior CSXT testing program, it would greatly surprise me if the BNSF units were placed into service and shortly thereafter the two-unpowered-axles concept was declared either a success or a failure. My expectation is that there will be a lengthy period of time during which the units are modified in a variety of ways and that these modifications will result in significant performance changes.