That measurement for a Thomas would be about 1 and 2/10ths inches or 3 cm.
Tops of the funnel and dome are slightly higher than the cab.
However the images on this page show a comparison between a Thomas and a a plain grey Rex, Mike, or Bert engine, and it appears they will quite a bit smaller than normal Capsule Plarail (though presumably still fitting the same track):
http://www.otakuboshi.com/product/3226
Tops of the funnel and dome are slightly higher than the cab.
However the images on this page show a comparison between a Thomas and a a plain grey Rex, Mike, or Bert engine, and it appears they will quite a bit smaller than normal Capsule Plarail (though presumably still fitting the same track):
http://www.otakuboshi.com/product/3226