WORKING TOGETHER ON RAILWAY NATURAL HAZARDS
Sesto Vespa
Transportation Development Centre, Transport Canada
Ian Naish
Rail Investigations, Transportation Safety Board of Canada
Abstract
Canada’s rail system covers thousands of miles and some of the most challenging terrain in the
world. Over the past few years, there have been a number of accidents and incidents involving
landslides and washouts including some loss of life and serious injury. A number of these events
have been investigated by Canada’s Transportation Safety Board, resulting in recommendations to
Canada’s Department of Transport and the Canadian rail industry. By 1998, the Department of
Transport had started to develop a multi-facetted effort to address such risks more systematically.
This approach included not only the industry and the regulator, but also non-railway experts in
academia. The most recent result of this approach was a symposium on landslide and washout risk
mitigation, aimed at developing concrete actions in the short and medium-term. This paper and
presentation will describe the status of these efforts, and the results of this Symposium.
Introduction.
The purpose of this paper is two-fold: first, to describe the results of the Canadian Transportation
Safety Board’s (TSB) investigations into a number of accidents involving landslides and washouts
on railway right-of-way. The second is to describe how the results of the Board’s investigations
and other information from Transport Canada (the safety regulator), industry, outside experts and
academia were used to develop a strategic and cooperative approach to reducing risks of future
incidents and accidents.
The TSB has conducted several investigations over the last ten years where there were issues
relating to earth embankments, drainage and track structure stability. In some cases, embankment
failures resulted in derailments. All of the incidents resulted in disruption to train operations and
some involved loss of life, typically that of the train crew. In other cases there were narrow
escapes.
As a bit of background, Canada’s geography is varied, with vast areas of mountain as well as of
prairie. Glacial and colluvial silts and sandy-silt materials cover much of the southern part of the
country, from east to west. Most railway grade construction in these areas occurred during the late
19th and early 20th century, with the limited construction capabilities of the day and little
understanding of soil mechanics. Early railway engineers simply cut and filled many sections of
Canadian railways using in situ materials with little or no compaction or regard for the suitability
of the material for railway embankments. These materials are inherently unstable when saturated
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with moisture, and can fail if adequate drainage is not available either naturally or provided by
design.
Examples of TSB Investigations in the Area of Track Structure Stability.
The following are some examples of investigations undertaken by the TSB, with summaries of the
issues identified in the investigations, as well as, in two cases, the resulting Board
recommendations:
Nakina, Ontario - On 19 July 1992, a westward CN freight train encountered a slumped
embankment, derailing four locomotives and eight freight cars. The locomotives fell into a lake.
Two of the three crew members were fatally injured and the survivor was seriously injured.
The derailment was caused by a breach in a nearby beaver dam, following heavy rainfall. The
failure of the dam resulted in a rapid lowering of water in the lake, which destabilized the track
subgrade and led to its collapse. The approximately 7 metre high embankment subgrade, was
composed of sand, gravel and silt, and was located at the end of the lake, with its toe of slope in the
lake.
The resulting TSB recommendations were, that Transport Canada, in collaboration with industry,
identify other locations where main track had been laid over weak sediments or where waters
adjacent to main track might be subject to rapid draw-down. Additional recommendations related,
inter alia, to the identification and implementation of corrective measures to stabilize subgrades
at vulnerable locations and a review of the adequacy of roadbed design criteria.
Conrad, British Columbia - On 26 March 1997, an eastward CN freight train encountered a large
roadbed depression and derailed. Two locomotives and fourteen railcars were destroyed. Both
crew members were fatally injured.
In the area of the derailment, the single main track and siding (west of the main track) run between
the Trans-Canada Highway, approximately 60 m (197 feet) to the east and 34 m (112 feet) above,
and the Fraser River, approximately 150 m (492 feet) to the west, and 50 m (164 feet) below. The
terrain is mountainous and heavily forested.
The subgrade collapse and subsequent derailment was attributable to water saturation and build-up
of pore pressure in loose, moisture-sensitive fills as a result of record-high precipitation, a lengthy
period of steadily increasing seasonal run-off from melting of an unusually heavy snow pack and
water-drainage failings. The railway subgrade could not sustain the resultant high pore pressure
and collapsed. An extraordinary volume of surface water runoff from melting heavy snow cover
and high seasonal precipitation was not carried away as intended by the drainage system above the
adjacent Trans-Canada Highway. The water soaked into the ground, migrated through the
highway fill, and infiltrated and destabilized the railway subgrade. The subgrade could not sustain
the resultant high pore pressure and collapsed. Contributing factors included the presence of
moisture-sensitive alluvial deposits in the bottom of the railway subgrade and the overlapping
nature of the highway fills which created a contiguous groundwater flow path into the railway fill.
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The resulting TSB recommendations to Transport Canada were, firstly, in collaboration with
industry, to identify locations where railway or adjacent highway roadbeds were laid on fills of silt
or similar material; to assess the adequacy of existing drainage for spring run-off, and to implement
monitoring programs to detect roadbed subgrade instability in the case of water saturation.
Secondly, they were to evaluate the effectiveness of track continuity warning systems as they
related to roadbed failures; to evaluate methods for confirming roadbed integrity during high risk
periods; and to sponsor research to develop more reliable technologies for roadbed and track
integrity monitoring.
Pointe au Baril, Ontario - On 7 April 1997, a northward CP freight train encountered a roadbed
slump, derailing 14 cars and the locomotive consist. 45 000 litres of diesel fuel leaked from the
locomotive fuel tanks and ignited. All three crew members were injured, one seriously.
The embankment, consisting of fine and uniformly graded loose sand with traces of some silt and
gravel, possibly with cobbles and boulders at the bottom, was built on a saturated peat layer (with
sand and silt underlying this layer) between two rock slopes. The embankment collapse was
attributable to a build-up of pore pressure in loose sand fill caused by the head of water created by
a beaver pond along the west slope of the embankment. There is significant beaver activity in this
part of Ontario and track crews continually monitor that activity, ranking the dams and ponds
according to the risk they pose to railway operations. Contributing to the head of water was the
rapid melting of snow during the two weeks preceding the derailment.
Creston, British Columbia - on 31 May 1998, a westward CP freight train encountered a roadbed
depression and derailed three locomotives and eight gondola cars. Ninety cubic metres of zinc
concentrate were spilled. The train crew suffered no injuries.
The railway track in the derailment area was built in 1895 on a bench formed by an alternating
sidehill cut and fill, 25 m above the flood plain of the Goat River, along the toe of a mountain
slope. The site is located downslope of an alluvial cone situated between two rock outcrops in the
mountain side. The mountain slopes are covered by a mature coniferous forest with some patches
of deciduous vegetation. The lower part of the alluvial cone is a discharge area for water infiltration
occurring on the upper part of the cone. The track embankment failed due to saturation and failure
of the subgrade fill. Contributing factors were the record rainfall, the performance of the drainage
system, the steep sidehill slope and the high susceptibility of the subgrade fill material to water
level changes.
Common Factors
Many miles of Canadian railway subgrade are susceptible to failure. The presence of
moisture-sensitive alluvial deposits in the heart of railway subgrades is the consequence of both the
limitations of construction capabilities and little understanding of soil mechanics at the time of
their initial construction (circa 1900). The ability to compact the subgrade and the importance of
such activity suffered from similar shortcomings. Many sections of Canadian railways were built
on fills in locations that can be exposed to unusual water events, whether high levels of
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precipitation, rapid melt of heavy snow pack, natural drain water collection or drainage disruption.
Associated build-ups of water, such as from beaver dams or blocked culverts, put subgrades at risk
of slumping when water-saturated.
Given the vulnerability of uncompacted, moisture sensitive alluvial deposits in railway subgrades,
proper drainage is critical. Ditches and culverts are an integral part of drainage systems but their
role is often underestimated and overlooked. They are usually given cursory inspection, if at all,
and drainage works commonly not visible from the track are assumed to be working as designed.
Action to identify and correct problem areas was usually taken only after an incident and rarely
sustained.
Subgrade slump events may leave wayside signal and communication systems intact, allowing a
permissive indication that is interpreted by most crews to convey the message that the track is safe.
Neither the train crew nor supervising rail traffic controllers receive any advance indication of
such subgrade failures.
Transport Canada’s Actions on Landslides and Washouts
Over the last decade, the Board has investigated a number of serious accidents, which resulted in
the recommendations cited earlier. Transport Canada responded to the first set of
recommendations from the Nakina accident by working with the rail industry to ensure more
focussed programs were established by the companies to deal with the identified risks. Much of
the emphasis at the time was to address concerns about high water levels, and railway companies
instituted a number of activities to better identify and respond to such incidents. Transport Canada
maintained a regulatory overview of these measures, including periodic monitoring. While these
measures were undoubtedly positive, a number of other issues such as identification of vulnerable
areas were pursued more sporadically.
However, the accident at Conrad, British Columbia in 1997 demonstrated that more action was
required to address the continuing risks of landslides and washouts. And the Interim
Recommendations of the Board on that accident were instrumental in developing more effective
and concerted safety actions. Transport Canada developed a multi-stakeholder group to deal
specifically with risks in the Fraser Canyon area of British Columbia. The department also hired
additional staff with direct expertise in roadbed and slope stability. In addition, the department
established, in partnership with industry, experts and academia, a number of research and
demonstration activities aimed at developing a better understanding of the risks and possible safety
countermeasures (technological and otherwise).
One research project undertaken involved the development of a new tool to help authorities
predict, manage and potentially prevent landslides that could damage rail or highway routes. The
three-year project was undertaken in cooperation examined the site of the 1965 slide at Hope,
British Columbia, and approximately 100 other sites in the Fraser Canyon, Thompson Subdivision
and Nelson areas of British Columbia. Among other factors, researchers studied climatic records
to correlate weather conditions with landslide potential. A new rockfall hazard rating system based
on geological and geotechnical factors was developed and tested. The analytical tool will be used
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to evaluate the risk of large-scale slope failure along the transportation corridors of southwest
British Columbia. The data can be used to establish maintenance priorities, or even to design
methods of mitigating or preventing rockfall damage.
Another research project involved the development of an electromagnetic field disturbance
rockfall detection system, which senses very small changes in the electromagnetic field set up by
the system using an active cable pair that is mounted between the rails. Rockfalls, landslides, and
washouts cause small changes in the electromagnetic field and is the basis for detection.
From several consultations with other federal departments, research institutes, and industry, it also
became apparent that various and disparate activities were on-going to identify, detect, and better
manage risks from natural hazards on Canadian railways. In an effort to better coordinate and
focus these activities, provide a critical mass for more elaborate undertakings, and to secure
additional funds through pooling of resources from partnerships, Transport Canada invited
meetings and discussions to explore opportunities for moving forward together.
The Contribution of the Railway Research Advisory Board
One of the most important contributors to this cooperative effort was the Railway Research
Advisory Board (RRAB). The RRAB was established many years ago to bring together officials
of Transport Canada, the railway industry, its suppliers, academia, and experts to discuss priorities
for railway research - safety being a key element. Over the years, this mechanism has been helpful
in facilitating sharing of knowledge and resources on numerous railway safety matters, including
locomotive axle failures, rail flaw detection technologies, use of Intelligent Transportation System
technologies for protection of rail crossings, wheel failure mechanisms, and numerous others. The
RRAB secretariat costs are paid by Transport Canada, but it has no other budget unless members
provide funds for specific activities.
One of the main items discussed at each RRAB session is safety research recommendations
resulting from Transportation Safety Board recommendations. The Interim Recommendations
from the 1997 accident at Conrad were no exception. For a while after the Recommendations were
issued, the RRAB kept abreast of the resulting research activities being undertaken by the industry,
Transport Canada, and others - several of which were joint initiatives. However, there was also a
growing recognition that there could be even more gained by developing a longer-term set of
priorities and associated action plans. As a result, the RRAB approved seed funding for a
symposium dedicated to slides and washouts.
The Symposium
In May of 2002, the RRAB hosted a symposium entitled “Slide and Washout Hazards: Managing
Natural Risks on Railways”. This three-day symposium began with an optional one-day study tour
of selected sites along the railway right-of-way through the mountains of western Alberta and
eastern British Columbia. Participants from Transport Canada, the Transportation Safety Board,
the National Research Council of Canada, railway companies, provincial governments (including
those associated with highways), the Geological Survey of Canada, researchers, suppliers,
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emergency preparedness experts, and officials of the United States government joined in both the
tour and the Symposium itself.
The specific purposes of the Symposium were as follows:


Crystallize a vision of what could be done to improve the management of natural risks from
slide and washout hazards on railways. This was to be done with sufficient clarity,
relevance and value to form the basis of new developmental programs
Stimulate the investment of resources to carry the programs out
The Symposium organizers further suggested some measures of success for this session. In
essence, they believed that evidence of new programs within one or two years addressed at
priorities of the Symposium would be critical. But in addition, they suggested that any measures
introduced should be capable of demonstrating significant improvements in risk reduction within
five years. Finally, there were expectations that a successful Symposium would be instrumental in
creating new synergies and capabilities.
The Symposium included opening remarks and suggested directions from an
internationally-recognized expert in risk reduction, railway company perspectives, the nature of
the hazards, existing risk-mitigation practices in both large and small railway companies, and
potential applications of other technologies to risk identification to name a few. This was followed
by a number of cross-functional workshops to discuss: hazard characterization; establishing a
context for future research, given the nature of the risks; hazard monitoring and detection
technologies; research needs and priorities; and, thoughts on the way ahead.
By the end of the symposium, consensus had been reached on the importance of developing and
implementing specific plans, based on the results of the workshops. It was agreed that an Expert
Panel be established to review a suggested program, which would then be provided to all
participants for consideration and comment. The intention remains, as from the beginning, to
finalize a specific set of research activities, identify resource needs, seek out partners, and ensure
that an appropriate structure is put in place to manage the implementation, monitor and evaluate
results. This effort is presently underway.
The Ground Hazard Research Program
The preliminary research program currently being considered by the Expert Panel is specifically
designed to appeal to collaborative arrangements. Its overall aim is to provide risk management
solutions for the railway industry to increase safety and reduce loss from ground hazard incidents.
The solutions will include the application of new methodologies for assessing hazards, monitoring
and detection technologies, and improvements to existing systems.
The research will cover ground hazard risk assessment and risk control elements as follows, among
others:
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Risk assessment
 Hazards classification system
 Database of incidents and case histories
 GIS based modeling tools for predicting events
 Critical weather thresholds that trigger events
 Field test methodologies for the Fraser Canyon and Thunder Bay rail corridors
Risk control
 Decision support tools for mitigating risk
 New technologies for monitoring and detection of events
The program is expected to extend over five years. Program development will be the primary focus
during the first year, with periodic adjustments to be made in response to research findings,
evolving priorities, and available funds. Several high priority projects fundamental to the program
would also be initiated during the first year, to ensure completion within the program’s life.
Conclusions
Since the unfortunate accident at Nakina, Ontario a decade ago, there have been some signs of
positive change in landslide and washout risks. Some of these have been mentioned earlier. In
addition, a quick review of accident frequencies is useful. In the period 1992 to 1997, there were
an average of 5 accidents per year because of subgrade failure, along with a total of 4 fatal injuries
and 5 serious injuries. Since that time, according to TSB statistics, there have been an average of
three derailments reported which were attributable to subgrade failure. There were no injuries to
the crew members reported in any of these cases. While these figures may appear promising, this
positive trend will likely only continue if past lessons learned are reinforced, and additional
measures are adopted when new information becomes available.
The premise of safety regulation in Canada continues to be that railway companies have the
primary responsibility for operating in a safe manner. This has recently been reinforced with the
introduction of a regulatory requirement that each company have in place a formal safety
management system (effective March 31, 2001). The role of government is to protect the public
interest, both through regulatory activities and independent investigations of accidents and
incidents.
The lessons learned over the past decade are that all of these roles need to be exercised properly if
safety performance is to advance. However, it has also been clear that cooperation, and where
appropriate, partnerships can play a significant role. As always, the challenge is to ensure that
efforts to work together towards a common goal are not seen to dilute the separate responsibilities
and accountabilities of all parties - whether it is the independent role of the accident investigator,
the need for regulatory action, industry’s need to manage their operations, or the independence of
researchers.
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The efforts to manage risks of landslide and washouts over the last decade, including the recent
multi-party symposium in this regard, provides a useful model of how such a cooperative and
balanced approach may reap significant benefits.
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