I understood from Guida dell'Africa Orientale Italiana that the Dorfu Valley was the valley on the other side of Devil's Doors.

James L. Woodward provided me with a Soviet Topographic Map.  It does not show any of these names.  None of the other maps I have seen have sufficient detail to give the valley names.  The cyrillic name for the valley through Devil's Doors comes close to Dorfur.  This is the form used on two pictures in le Ferrovie Coloniali Italiane. One of those with the 'Dorfur' caption is obviously Tunnel 28.  It is shown on the page devoted to the west side of the valley.

GRAF©1975
"Un treno misto con doppia trazion, esce fumando da una galleria nei pressi di Dorfur." is the caption given in le Ferrovie.  In English, this is approximately, "A mixed train with double traction, enticing smoke from a tunnel in the neighboorhood of Dorfur."  The bridge has at least two arches. Such a combination is not shown on Jim Woodward's map of the Devil's Doors area.  If one believes the operating directive, the tunnel is on the downhill side of the bridge. The directive says that the locomotives will always be pointed up hill.  This was not followed strictly in 1961 as seen in my pictures on chasing trains.  There, it clearly shows the locomotive pointed dwon hill.

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