I think this is a great project and will be an important part of presenting the historical significance of the railroad to the visitors. I do not know anything about the project program, but I assume this will provide a place to properly store and display historic artifacts, photos, and documents. It will be a nice addition to the visitor experience. It will be important for this building to be located near the depot and parking lot so that people will walk there as a part of their visit.
However, I have to say that I share CJ's concerns about the form the building has taken. Its size and style might disrupt the historic depot's current role as the visual focal point for visitors to the railroad. The potential insinuation of historic authenticity threatens what is already an extremely authentic landscape. I would not have a problem with the project's size if the building took on an architectural expression that did not compete with the depot, which really should remain the center of attention.
It seems to me that there are several appropriate architectural strategies:
One would be to construct what would externally replicate a building or buildings that are no longer extant, but were present during the railroad's period of historic significance. I am not familiar enough with Chama's history to know if any appropriate structures existed.
Another strategy would be to create something that would be seen as representative of buildings one would either have found along Terrace (commercial storefronts and such), or alongside a rail yard (warehouses, industries, etc.); but at the same time would subtly suggests its true nature as a contemporary facility and not be a replica per-se. This is similar to what has been done, except by choosing to mimic the one building that should be unique, the design does not sufficiently recede into the context of the site. Ideally, the historic references of the building would serve as camouflage.
The final strategy would be to make a building that might gently reference the historic materials and architectural forms of the context, but was an explicitly contemporary intervention. This solution would probably be controversial, but it would be the most honest.
Anyway, I understand the train has probably left the station on this one. Just wanted to share my thoughts on the subject.
Thanks.