Under the Whyte notation for the classification of steam locomotives, a 2-8-8-8-8-8-2 has two leading wheels, five sets of eight driving wheels, and two trailing wheels. Because of its length, such a locomotive must be an articulated locomotive. It is not longer than a normal articulated; the fourth and fifth sets of drivers are located under the tender.
Other equivalent classifications are:
UIC classification: 1-D-D-D-D-D-1 (also known as German classification and Italian classification)
AAR classification: 1-D-D-D-D-D-1
French classification: 140+040+040+040+041
Turkish classification: 45+44+44+44+45
Swiss classification: 4/5+4/4+4/4+4/4+4/5
The equivalent UIC classification is to be refined to (1'D)DDD(D1').
The Baldwin Locomotive Works submitted a design for a 2-8-8-8-8-8-2 quintuplex to the Atchison, Topeka, and Santa Fe Railway. The proposed quintuplex was essentially a cross between the cab-forward locomotives for the Southern Pacific and the Triplexes built for the Erie and Virginian, with a cab at the front for the driver and the rear cab for the fireman.
- Solomon, Brian, 2015. The Majesty of Big Steam. Voyageur Press. ISBN 978-0760348925
- Drury, George H. (1993). Guide to North American Steam Locomotives. Waukesha, Wisconsin: Kalmbach Publishing Company.