Geosynthetics June/July 2021 - 13

Case Study
NPA geocell for a
railway line repair in
a permafrost region
By Sanat Pokharel and Marc Breault
C
hurchill is a port city located on Hudson Bay in northern Manitoba,
Canada. The nearest roadhead village of Gillam is 156 miles (252 km)
south. Hudson Bay Railway (HBR), the only mode of land transport to
Churchill, was completed in 1929. This single-line railway track has served the
northern port of Manitoba uninterrupted; however, due to the lack of timely
maintenance and upgrades, it gets damaged, causing service interruptions and
ultimately leading to an extra burden on the maintenance budget. The railway
was built on extremely soft ground that crosses many stretches of permafrost.
In recent years, permafrost degradation caused by rising temperatures and
other forms of human intervention have impeded the smoothness of the rail
ride and reliability. The flood in spring 2017 severely damaged the rail line at
all stream crossings. This rendered the only mode of land transport to the town
unusable, and all basic supplies were airlifted, causing further hardships where
the daily temperature remains subzero for more than eight months a year.
In May 2016, the authors visited the site to assess the condition of the
railway track and recommended high-strength geocell reinforcement to
control the lateral spreading of ballast/subballast material and protect the
frozen subgrade. However, after the 2017 flood, the intent was a quick-andaffordable
solution to repair the damage caused by recent track washouts
and reestablish access to the town at the earliest possible time. An innovative
design was required to complete the job in five weeks at a total cost in the
range of 20%-25% of the more than $100 million initially anticipated for the
rehabilitation work.
For the railway embankment structure, a robust structure to withstand
the railway traffic while optimizing the construction costs and using the
available resources in that area was proposed. Considering the general rule
recommended by Pokharel et al. (2017) for other pavement structures, the
railway track was designed with high-strength novel-polymeric alloy (NPA)
geocell reinforcement.
PROJECT HIGHLIGHTS
NPA GEOCELLS AND
GEOTEXTILES FOR RAILWAY
OWNER
Arctic Gateway Group LP
LOCATION
Manitoba, Canada
CONTRACTOR
Paradox Access Solutions Inc.
DESIGN ENGINEER
Sanat Pokharel, Stratum
Logics Inc.
GEOSYNTHETICS PRODUCTS
NPA geocells, woven and
nonwoven geotextiles
GEOSYNTHETICS MANUFACTURER
PRS Geo Technologies (NPA
geocells), Paradox Access
Solutions Inc. (geotextiles)
Sanat Pokharel, Ph.D., P.Eng., is a principal
engineer at Stratum Logics in Acheson,
Alb., Canada.
Marc Breault is president of Paradox Access
Solutions in Acheson, Alb., Canada.
All figures courtesy of the authors.
www.GeosyntheticsMagazine.com
13

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Geosynthetics June/July 2021

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