I have no affiliation with this site. I wish there was a similar site for HO scale.
It's exactly what the title says, a searchable data base of locomotives
http://spookshow.net/locos.html
Henry
COB Potomac & Northern
Shenandoah Valley
An HO-scale locomotive database would be exponentially larger than N and a lot more challenging to maintain.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
This has been my go-to for years. Mark does an excellent job of reviewing locomotives. I can only imagine what is roster must be like!
Scott