This has been an interesting thread to read. Most of the topics that need to be discussed when considering building a new locomotive have been covered. The most important question is why? Why should you spend the time and money to build something that you don’t have when there are so many engines that could be restored?
Here is a philosophical question to consider… Why should an important artifact, such as a surviving 19th century artifact, be operated when a accident could destroy it?
The concept of conservation is in direct conflict to the premis of many operating museums. The work required to restore, and maintain a steam locomotive in operating condition will over time destroy the signifiance of the artifact. Especially when poor records are kept when the work is preformed.
What if one of the park engines in Durango or Alamosa were restored and then involved in a major derailment or boiler failure where the engine was destroyed? Would the restoration be worth it? Would the limited experience of a few be worth the loss of those to follow?
A new steam locomotive would be justifiable at a museum that wanted to operate a train and preserve the locomotives in it’s collection. The advantages of modern construction techniques could be exploited without having to compromise the historical integrity of the piece. It would give people the experience with out the risk to the artifact.
As for the technology, many of the skills and techniques that were used in the original construction of locomotives have been replaced by better, more reliable techniques. The builder would be a fool to build a locomotive intended for operation and not take advantage of the new technology. With proper finishing a weldment would look the same as a casting and last longer under more abuse.
I think that repoductions is the way of the future for smaller engines. I do not think that railroad museums will lead the way. Too many people with too many egos to find that magical concensus. Once the concensus and justification is made the money will not be that big of an issue.
Now the economy...
I will now shut up before I upset too many people.
The Devil’s Advocate