Much information about his work for the Atlantic and Great Western RR (the AGW) is available at http://www.railfan.net/news/c0000024.htm and at related pages on this site. The site also contains photographs, maps and other information about the AGW, which was later merged into the Erie RR. Some of his structures are still standing, south of Buffalo, New York, USA.
A book was published in 2002 entitled EUROPEAN CAPITAL, BRITISH IRON, AND AN AMERICAN DREAM, edited by Gifford and Ilisevich. This book describes the AGW RR in detail as well as TWK's part in the design and construction. However the book was written by a person who fought with TWK on many issues so it is not very complementary.