Ventilating the
Elkhorn Tunnel, Norfolk & Western Railway
The full description of this
important piece of work has been furnished
by Mr. Charles S. Churchill, engineer, Maintenance of Way. The tunnel
is through the Flat Top Mountain in West Virginia, which forms the
divide between the waters flowing into the New River, on the east, and
those flowing into the Ohio, by way of Elkhorn Creek and Big Sandy, on
the West. There is an up-grade through the tunnel going east of 1.4 per
cent. The tunnel is lined throughout with brick, and has a single track
through it, though the Norfolk and Western is a double-track road. The
method employed in the Pracchia tunnel in Italy having been explained
by the engineering journals, formed the basis of the method adopted at
the Elkhorn tunnel.
Notes taken prior to ventilation showed that in Summer 17 to 55 minutes
was required to give the air in the tunnel time to clear. The shortest
time noted was 20 minutes, in the Winter. The method consists in
flaring out the portal at the west end and running two walls parallel
to the track, about where the original line of the tunnel stood. This
made an enclosed triangular area on each side, and into this box air
was forced from two fans. At the narrow end of the triangle an opening
was left which formed a kind of nozzle. The machinery consisted of two
fans, 14 feet in diameter, each operated by an engine of 75 horse-power
; the number of revolutions per minute which delivers air at one ounce
pressure at the outlet of the fan being 118, and the rated delivery at
this speed being 168,558 cubic feet per minute per fan. Details of a
number of most satisfactory tests which were made are given by the
author. The idea was to blow the smoke of east-bound engines ahead of
them, and the west hound, being on a descending grade, would
practically give no trouble from smoke.
A three-engine east-bound train passed through the tunnel in six
minutes while the fans were running at 142 revolutions per minute. An
observer on the tender of the first engine, cab windows being open,
reported the tunnel entirely clear two thirds of the way through, and
no objectionable smoke anywhere. Another observer rode on the second
engine, with windows open ; he could see the smoke of his engine seven
cars ahead of his engine, with no smoke behind. Another, on the rear
engine, in the cab with windows open, found tunnel practically clear,
and no smoke behind. An observer at the east portal reported that smoke
came out two minutes ahead of the first engine.
(from a 1901 magazine, in the
public domain)