The Billings herald. [volume] (Billings, Mont.) 1882-1885, 1882-06-22
MULLAN TUNNEL.
The Most Difficult Piece Of Engineering on
the Northern Pacific.
The Approaches-The Length-Its Altitude
and Other Interesting Facts.
Work Begun at Both Ends and in the Cen
ter-Penetrating the Granite.
.Muir's Contract.

Mullan tunnel now penetrates the main
range for a distance Of about 700 feet.
Blasting takes place on an average once
every thirty hours, One hundred and fifty
pounds Of giant powder three cases. is used
for every charge, and the tunnel is dcepened
about six feet at each blast.
The mouth of the tunnel is about 100
feet up the mountain; quarter of mile
below, the railroad grade on the mountain
side is at least 300 feet higher than the bot
tom of the canyon.
It is estimated that the debris which will
come out at the east end of the tunnel will
be sufficient for constructing the road-bcd
along the steep mountain side for 600 OF
800 feet from the mouth of the tunnel. The
fill already constructed in this way is pro-
badly 200 feet in length.
There is now a large force of men
at work on the tunnel approach on the
west, but the work is very difficult and ne
ccssarily slow 1t is said to be the most
difficult piece of work of the kind ever at.
tempted on the Pacific slope. The diff.
Guilty lies in the fact that the earth at that
particular place is full of springs. This
condition of the soil extends from the point
at which the tunnel will enter the mount
ain, to several hundred feet below. AS the
cut has to be some thirty or forty feet deep,
it is like attacking huge quagmire and at.
tempting to dig it out by the roots. Super
intendent Andrew Muir estimates that il
will require five months to complete this
particular work.
The shaft, which is being sunk SO that
the tunnel work may be attacked from a
central point, will be down the required
the drilling and hoisting at this point has
been done by hand. Part Of the machinery
for the hosting works and air COMPRISING
apparatus-for they intend using the Bur
and has not arrived yet. 1t is expected.
however, that the machinery, etc, will all
be in position within week or two.
With regard to storing giant powder, the
company has profited by experience and
now keeps it where it will do no damage in
case of all explosion. Two powder houses
have ;been built on top Of the main range,
over the tunnel. These contain at present
24,O0O pounds of the explosive-enougl, at
a rough estimate, to do the blasting for
about 100 feet of tunnel work
The electric light, now in use in the tun-
nel docs not seem to work very satisfac-
torily.
1t is estimated by those who ought TO
know that the tssnsel will be co:.9i i,icse,i
within a ycar.-LHelena Independent.
The following additional fac,s relative 70
the tunnel were obtained from Gen. Ander-
son, Chief Engineer of the Northern Pacific
Railroad Company, during his stay III Bill
lings this week:
The eastern end of the Mullan tunnel
commences at distance of fifteen miles
from Helena, in northwesterly direction,
and is to extend $500 feet.
The contract, which calls for the compile
ton of the work by the first day of June,
1883, was let in December of last year.
But one face is exposed just at present, but
in a few months three others will be opened
so that drilling and blasting can be carried
on from the center toward both ends, and
from each end toward the center.
The tunnel proceeds at the rate Of five
feet day, through the solid wall of granite
of which the mountain is composed.-ED