Geosynthetics June/July 2021 - 20

NPA geocell for a railway line repair in a permafrost region
reinforcement and controls the loss of ballast
material by lateral spreading.
All possible precautions were made
to cause minimal or no damage to the
unspoiled surrounding ground. Better
preplanning on construction activities
involving all the subcontractors can
improve overall productivity of a project.
At times, the primary contractor
and the client's engineers encountered
misunderstandings due to their different
knowledge of geocell technology.
However, as the work progressed, the
work went smoothly.
The damage to this railway infrastrucFIGURE
9 Completed rail reinstallation near switch at Milepost 414
This project also showed that the
FIGURE 10 First train arrival, Oct. 31, 2018, in
Churchill in almost two years
knowledge and experience of the construction
crew to work in a harsh climate
under difficult limitations play a very
important role. The project was completed
in 33 working days at a cost of
about 20% of what was initially anticipated
for conventional rehabilitation
work. The savings were primarily because
of the reduced construction time, use of
the washout material and working right
on top of the existing subgrade without
removing the degraded subgrade
material. The construction equipment
available was limited, so a coordinated
approach between the geocell installers,
culvert pipe installers and earthwork
crew were of utmost importance to getting
the job done in a timely fashion.
Unless a ballast-tamping method that
does not damage the reinforcing geocell
at the ballast layer is developed, the ballast
layer cannot be reinforced, so the loss of
ballast material by lateral spreading in this
railway line is expected. So, there is a need
to find a different technique in the remote
area to do the tamping that allows ballast
20
Geosynthetics | June July 2021
ture was caused in part by the melting
permafrost, unmanaged cross-drainage
structures and erosion-prone embankment
slopes. The permafrost degradation
along the railway track is evident by
the uneven settlement along the railway
length and subsidence of the existing
culvert pipes. Lateral spreading of ballast
was another problem. The railway line
is in operation, but a 93-mile (150-km)
stretch of the railway line north of Gillam
is still in need of repair. Once those areas
are also repaired, the rail line can be run
at 31 mph (50 kph) as designed. There are
many locations where the ballast and subballast
material is scattered and spreading
laterally. A confinement technique such
as high-strength geocell reinforcement
can control that and reduce the maintenance
costs in the long run.
This rehabilitation work was completed
just when daytime temperatures
started falling to subzero in that region
(Figure 9). Rail access to Churchill was
reestablished on the last day of October
2018 after the track was inspected
and approved for operation by the
Transportation Safety Board of Canada.
The railway has been in operation for
two full seasons after the rehabilitation
without any major concerns. Figure 10
shows the first train arriving in Churchill
after the rehabilitation work.
Geosynthetics June/July 2021

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