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Straight down
the line
The New Measurement Train inspects tracks at speeds of up to 125mph and can
cover the main intercity network in just two weeks. Katie Silvester reports
No stone left unturned
Network Rail’s High Output Ballast
Cleaner (HOBC) allows ballast to
be cleaned and replenished without
disturbing the tracks.
The 800-metre, 3,200-tonne train can
work through around 550 metres of track
in a typical midweek eight-hour night
shift and up to 1,280 metres in 16 hours at
weekends, moving at around a quarter of
a mile an hour.
The HOBC excavates ballast –
made from crushed natural rock – from
beneath the track, while holding the
track in position. Excavated material
passes through large vibrating sieves,
which remove the smallest pieces.
Ideally, pieces of ballast should be
between 28mm and 50mm in diameter,
but ‘fines’, or fine pieces of ballast, are
created over time and, when mixed with
rainwater, can become stuck together to
create solid lumps, reducing the ballast’s
drainage properties and decreasing
cushioning for passing rolling stock.
After sieving, the larger pieces of
ballast, mixed with new ballast, are
returned to the track.
Nick-named the Flying
Banana, Network Rail’s
New Measurement Train
(NMT) is a familiar sight on
Britain’s railway network.
The train, which was the
first of its kind in Europe, measures track
alignment and monitors the condition of
overhead wires. Created from a converted
Monitoring equipment
onboard the NMT
Inset: The ‘Flying Banana’
from the outside
HST, it can reach speeds of 125mph, which
enables it to slot easily in between services
without affecting the timetable.
The NMT only inspects the main
intercity routes – East Coast, West Coast,
Midland and Great Western Main Lines.
The monitoring process is continuous, so
every section of track along these routes is
inspected once every two weeks.
The High Output
Ballast Cleaner
PAGE 28 AUGUST 2010