(John Kemp is a Reuters market analyst. The views expressed are
By John Kemp
LONDON, July 10 Notwithstanding the appalling
train disaster in Quebec this month, U.S. government accident
data show both railroads and pipelines are relatively safe ways
to move crude oil and other hazardous liquids over long
The Canadian derailment and subsequent explosion, which
killed at least 15 people and left dozens more unaccounted for,
has sparked a renewed debate about whether it is safer to move
crude and other hazardous liquids by tank car or pipeline.
Back in May, Canada's Prime Minister Stephen Harper warned
that rejection of the proposed Keystone XL Pipeline would lead
to an increase in oil shipments by rail, which he called "more
environmentally challenging" than pipelines.
Keystone supporters are poised to cite the derailment as
evidence that pipelines are safer. But the rail industry has
already begun to push back. "Rail has fewer spills that release
less crude oil than other transportation modes," according to
the Association of American Railroads (AAR).
The association has published a battery of statistics to
show pipelines have more and bigger spills than rail operators.
It estimates railroads spill just 0.38 gallons for every million
barrel-miles of crude moved, compared with an estimated spill
rate of 0.88 gallons on the pipeline network.
A barrel-mile is measure of through-put that signifies one
barrel moved one mile.
So who is right? Is it safer to ship crude by pipeline
rather than tank car? The answer: it depends.
Table 1: link.reuters.com/gum59t
Table 2: link.reuters.com/jum59t
AMOUNT SPILLED IS SMALL
The first and most important point is that the amount of
crude and other dangerous liquids spilled on both the railroads
and the pipeline network is small when compared with the
enormous volume of crude and other flammable, explosive and
toxic liquids they carry every year.
In the United States, there are over 182,000 miles of
pipelines carrying hazardous liquids, according to the Pipeline
and Hazardous Materials Safety Administration (PHMSA), which
regulates both the pipelines and dangerous materials carried on
any other mode of transport such road, rail, air and sea.
In 2011, the total volume of hazardous liquids transported
on the pipeline network hit a record 5,888 billion barrel miles.
Crude accounted for accounted for around 30 percent of the
volume transported (1,813 billion barrel-miles).
But hazardous pipelines also carried refined products (1,602
billion barrel-miles), highly volatile liquids like propane (539
billion barrel-miles), and carbon dioxide (1,932 billion
barrel-miles) which is toxic in high concentrations.
Over the last decade, U.S. hazardous liquid pipelines have
spilled fewer than 30 barrels of crude and other hazardous
liquids for every billion barrel-miles transported.
The number of fatalities as a result of serious and
significant incidents has averaged fewer than two a year (with
five more injuries). Damage to property has averaged $218
million (Table 1).
The government does not publish directly comparable
statistics on the volume of crude and other hazardous liquids
carried on U.S. freight trains, so it is difficult to provide
precise comparisons for the railways. Most estimates are based
on a confidential sample of waybills (transit records) obtained
from the Surface Transportation Board, which regulates freight
rates in the rail industry.
Historically, the volume of hazardous liquids moved by train
has been 1-2 orders of magnitude smaller than by pipeline. But
the AAR statistics, which are based on its own proprietary data
and waybill-derived volume estimates, suggest the spill rate is
very similar to the pipelines, and the industry operates very
safely in general.
PIPELINES MUST SHUT PROMPTLY
Which method of transport is "safer" depends on whether the
object is to minimise the number of spills (in which case
pipelines have the advantage) or their size when they do occur
(in which case rail freight is better).
Pipelines are very safe but they move enormous volumes of
crude oil and other liquids under considerable pressure, so if
there is a serious rupture the potential volume of liquid
released is much higher.
Beginning in 1971, the U.S. National Transportation Safety
Board (NTSB) has published a series of reports which emphasise
that if pipelines are to operate safely, they must shut down
quickly following any incident to minimise the amount of liquid
released into the environment.
All pipelines therefore contain a series of manually
operated or automated valves along their length so affected
sections can be isolated quickly.
They are equipped with monitoring equipment and alarms to
check pressure remains constant and that the volume of material
entering each segment matches the volume of liquid coming out,
to confirm the line is not leaking.
Once the alarms go off, control room staff are under orders
to shut down the line quickly, generally within 10 minutes,
unless they can resolve the problem and confirm the line is
operating safely. If enough alarms sound or a major one is
triggered, the line must be shut immediately until a visual
inspection confirms that it is safe to resume operations.
Pipeline operators are required to identify line sections
that pass through high consequence areas (HCAs), those with
substantial populations or environmentally sensitive habitats
and watercourses, and take special measures to reinforce them
and monitor for potential integrity problems.
Provided the 10-minute rule is adhered to and the line is
shut promptly, spillages should be kept to no more than a few
hundred or thousand barrels at most. Larger spillages have
normally occurred when control room staff have ignored alarms,
valves have not closed and pumping has not ceased immediately.
By contrast, the amount of crude and other hazardous liquids
that can be spilled from a freight train is much smaller because
the maximum volume that can be carried in a single tank car and
on the train as a whole is much smaller.
COMPARISON OF ACCIDENT STATISTICS
Between 2002 and 2009, there were just over 3,000 instances
in which hazardous liquids were spilled from pipelines, compared
with almost 5,000 escapes from rail tank cars, according to the
PHMSA's incident recording database.
These numbers include all hazardous liquids, not just crude
oil and refined products. But since any escape is a potential
threat to human health and the environment it is reasonable to
look at the totals rather than just crude oil, and it is more
meaningful because until very recently the railroads carried so
The average escape from a pipeline was 260 barrels, compared
with just 17 barrels from a container on the rail system.
The pipeline average is biased upwards by a small number of
very large spills. Two-thirds of pipeline spills released less
than 10 barrels. But more than 30 percent of all the liquid
spilled was released in just 10 large incidents where over
10,000 barrels were spilled each time.
In the worst case, 49,000 barrels of crude oil were spilled
from an above-ground storage tank which had corroded at Cushing
in Oklahoma in 2006, though almost all of it was subsequently
But the typical pipeline spill is very small. The median
amount of hazardous liquid spilled from a line is just 3
barrels, which is not much different from the median 1 barrel
spilled on the railroads (Table 2).
On balance, both pipelines and trains have a good safety
record transporting crude and other hazardous liquids in North
Adjusted for the much larger amount of hazardous liquids
that they carry, pipelines spill less, though the difference is
not huge. But crucially, pipelines must shut very promptly in
the event of an accident to avoid a catastrophic release of
Safety culture is critical. Following a series of large
pipeline spills in the last four decades, and repeated pressure
from the NTSB and now the PHMSA, most pipeline operators seem to
have improved their safety culture. Control rooms are instructed
to shut down first and ask questions later if there is hint of
even a small leak.
But as events in Quebec have shown, every spill has the
potential to inflict catastrophic harm, so maintaining a strong
safety culture that puts safety ahead of all other
considerations is essential.
(Editing by Pravin Char)