The sun. [volume] (New York [N.Y.]) 1833-1916, 1890-05-05
WORK ON THE ST. CLAIR TUNNEL,
An Eighty.ton Shield Driven by Hydraulic
Jacks Through the Clay.


OTTAWA, May 4-The construction Of the
great tunnel under the ST. Clair, River. between
Sarnia and Port Huron. is attracting much In
terest among the great trade carriers between
the West and East The completed tunnel will
be over ono mile in length. 2,310 feet being I'M
der the river, 1910 feet under dry ground
on the Michigan side and about 1000
ieet on the Canadian side Fifteen hundred
leet OF the portion under the river will
be almost level. falling eastward slightly to
cause any water that may get into the tunnel
to run to the Canadian side The total length
OF the ascent on the Michigan side will be about
4,SOO feet, and on the Canadian side about the
same. The length of the open cutting at the
Michigan end will be 1880 feet, and at the
Canadian side about 5000 feet. The depth
OF the lowest part OF the tunnel from
the mean level Of the river will be 81
feet, which is much higher than at first antici-
pnted, but the borings showed such good
material that 1t was decided that the tunnel
could be built 30 much higher. The minimum
depth of the top OF the tunnel below the bed Of
the river will be about fifteen feet 1t will have
o clear internal diameter OF twenty feet and will
have single track. 1t was at first proposed to
tMnns pvt
tunnels could be built moro choaply than one
do4ble-track tunnel. If this tunnel Is a success
bnild second one alongside OF 1t. The
Michigan portal OF the tunnel will be about
some change will be necessary in the running
OF the trains. The Canadian portal OF the tam
Sarnia.
The work Is being pushed ahead day and
night under the SUPERVISION OF Thomas Muir
shield is the tunnel digger and weighs about 80
toms toms is driven Ry "a lacks Of 25
rad IN mr. fhn hin1I
is moved ahead by pumping water into tho
Jacks and forging the rams out against the
about eighteen inches, having been obtained,
the Jacks are then sent home the same way.
is then put up the lover hair VIII H T era iIHn
which Is attached to he rear OF the shields and
operated with crank by four or Ave men. A
ring is finished. Preparations are then made
for another advance. In the mean time tho
the shield making room for another aivanco.
as Sds oD is all hbTCSG4 the shsd and
dumped on fiat cars to be ken away.
Tho shield Is about three inches larger than
the vacancy which it leaves between the iron
lining and the surround nG clay is filed with
cement gr9ut, 10 prevent any movement of the
In the tunnel for convenience in hauling mate
rial, Tho whole works are lighted with cleo
The doubt may be expressed nbout the pos
sibity Of making the two shields meet truly in
this point. MIR. HilmRn. the engineer In charge
OF tho construction OF the tunn"l, takes lines
and measurements every day and prepares o
the shields, which is handed TO tho workmen,
and tho shields are shfted according to the
diagram by using Jacks more or less on either
side or at the top or bottom MS may be re-
CURED to keep the true line. When the clay is
very soft 1t is more difficult to keep the shield
In line but 80 far the clay has been fairly good
The material has been little easier to remove
on the Canadian side. which accounts for tho
somewhat better time made lately GU that end.
Over twelve feet of tunnel have been mnde
some days on the Canadian side. on tho Amer
per day.