Geotechnical News • March 2017
47
COMMEMORATIVE EDITION
son Road (1868-1870) to connect
the missing links of the water route
from Fort William to Red River. The
former, built by the Royal Engineers,
ranks with the greatest engineering
achievements of the 19th century.
As the villages and towns grew into
cities, dams and water supply res-
ervoirs were required for domestic
consumption, water power, and indus-
try. Commensurate with the status of
the new Canadian Confederation of
1867, at the end of the 19th — early
20t th centuries, monumental public
buildings made their appearance,
sometimes with attendant settlement
problems — the Empress Hotel,
Victoria, and the Victoria Memo-
rial Museum, Ottawa being prime
examples.
The science of soil mechanics and
the formal practice of geotechnique
were to be events of the 20th century.
Nevertheless, before the analytical
tools invented by Karl Terzaghi, were
available, good civil engineers, by
empirical methods, were able to devise
solutions that were precursors of mod-
ern geotechnical engineering practice.
Sir Sandford Fleming (1827-1915)
was Canada’s preeminent railway
engineer of the 19th century. Born in
Scotland, where he studied survey-
ing and engineering, Fleming came to
Canada in 1845 at the age of eighteen
and entered the service of the Northern
(Ontario, Simcoe and Huron) Rail-
way. His first great “empire-building”
achievement came as chief engineer
(1868-1875) of the Intercolonial Rail-
way, which came about as a condition
of bringing the Maritime Provinces
into the Canadian Confederation.
The most noteworthy engineering
work on the line was the construc-
tion of two 1,200-foot-long truss-
span bridges over branches of the
Miramichi River near Newcastle,
New Brunswick. Initial test bor-
ings arranged by Fleming at the two
river crossings, and surface outcrop-
ping inferred a sandstone bedrock.
However during construction, when
settlement of the northwest bridge
piers was observed, Fleming stopped
construction and ordered a second set
of borings. At the southwest bridge,
a dense gravel and sand stratum under-
lain by sandy-silty glacial till, allowed
safe construction of the bridge piers to
the original design.
However, at the northwest bridge, the
bearing stratum was underlain by a
thick deposit of clay-silt — the cause
of the settlement. Fleming devised the
first recorded static penetration tests,
using cased iron rods within the bore
holes to eliminate friction, in order to
determine the loads which the dif-
ferent strata in the riverbed would
support.
As a result of the tests, Fleming
needed to enlarge the pier bases in
order to spread the load, and he pre-
loaded each pier until the settlement
stopped.
In 1871 Sandford Fleming was
appointed engineer-in-chief to super-
intend the surveys for the Canadian
Pacific Railway through the Rocky
and Selkirk Mountains. He surveyed
the route through the Yellowhead Pass,
which is now followed by the Cana-
dian National Railways, and he was
the first to demonstrate the practicabil-
ity of the CPR route through the Kick-
ing Horse, Rogers, and Eagle passes.
After 1880 Sandford Fleming devoted
himself to scientific and literary work.
Among his many other achievements,
he was the pioneer of the 24-hour sys-
tem of time reckoning and of standard
time, necessary for the scheduling of
transcontinental train service. Flem-
ing also designed the first Canadian
postage stamp, the three-penny issue
of 1851. It depicts the beaver, that
ubiquitous resourceful civil engineer
of the Canadian wilderness, building
his dam.
Now operated by CN Rail, the Grand
Trunk Railway initiated the St. Clair
Tunnel, built between Sarnia, Ontario
and Port Huron, Michigan from
1889- 1891. The tunnel replaced a
slow ferry service in providing a
primary Canadian link to Chicago,
centre of the North American railway
universe. After two previous attempts
had failed, the Grand Trunk chose the
experienced civil engineer
Joseph
Hobson,
born in 1834 at Guelph,
Ontario, as chief engineer of the
tunnel company. Hobson’s “combina-
tion of daring, tenacity, and engineer
ing knowledge” proved to be just the
right combination to ensure success of
the venture. In investigating the site,
Hobson made detailed borings in line
with the proposed route, taking 110
soil samples. These revealed that the
riverbed consisted of a thin layer of
“treacherous blue clay” above a shale
bedrock. To execute the large bore
tunnel, two huge cylindrical shields
with knifelike leading edges were
driven from each end by hydraulic
rams through the “slippery” clay “like
a giant cookie cutter.” The clay layer
above the crown was so thin — only
10 to 12 feet — that the workers
claimed that they could hear the bands
playing aboard steamers passing over-
head. This first international tunnel in
North America, driven subaqueously
through such perilous clay, was widely
reported in trade journals throughout
the world and considered an engineer-
ing marvel of the day. Many of the
precedent-setting techniques employed
in the project have been adopted in
modern tunnel engineering practice.
Hobson’s tunnel survived a century
of active service but has recently
been replaced, not because of any
failure in its engineering, but because
its dimensions were made obsolete
by inter-modal rail systems such as
double-stack container cars and tri-
level auto cars.
