*See John Sweetser's note in the comment section below.

Southern Pacific cab-forward locomotive No. 4202 steams through Soledad Canyon near Ravenna (between Lang and Acton) in this undated 1940s or 1950s photograph by Herb Cearley of Long Beach. Color transparency distributed by Blackhawk Films.

Engine No. 4202 (same locomotive) at Watsonville, June 1955. Click to enlarge.

Or rather, the train has come to a stop near Ravenna; a number of people are standing around it for an unknown reason.

As the name implies, a "cab forward" put the driver's compartment at the front of the locomotive, in front of the boiler — opposite from "normal." Click here for a driver's eye view from inside a cab forward as it pulls into the Saugus depot in the 1940s.

Like many (but not all) SP cab forwards, Engine No. 4202 had a 4-8-8-2 wheel configuration — four leading wheels followed by two sets of eight driving wheels and a two-wheel trailing truck.

Southern Pacific was the only line to order cab forwards, 256 in total. It preferred them for the treacherous tunnels and curves along its course through and over the Sierra Nevadas. They were great for visibility; the driver wasn't blinded by smoke from the boiler when it went through a tunnel or snow shed. But it was lousy for the driver in a collision, for obvious reasons.

Engine No. 4202 was built by Baldwin Locomotive Works in 1939. It was a Class AC-8, the fifth of the 4-8-8-2 classes, which came with bigger windows than its predecessors as a standard feature. All AC-8 cab forwards — Nos. 4177-4204 — were built between August 18 and November 26, 1939. All of them were scrapped between November 26, 1954, and April 24, 1959 (not in numerical order).

Today just one cab forward exists, SP No. 4294, built in 1944. It was the last cab forward built — and the last new steam locomotive of any type ordered by the Southern Pacific. It is in the California State Railroad Museum in Sacramento.

Further reading: ClassicStreamliners.com.