The Alaska Contractor - Summer 2008

The blasting crew from
Advanced Blasting Services
loads explosives in the rock
above Moody Tunnel during
the demolition in April.
structure, trains will ultimately be able
to haul double stacked loads between
Anchorage and Fairbanks with two 40foot
containers stacked on top of each
other. Higher, wider loads mean more
revenue for the railroad.
Located at Mile 353.6 of the Alaska
Railroad in an area known as Healy Canyon,
which has a long history of landslides,
sinkholes, and tunnel cave-ins, the
tunnel was originally built with drill and
blast methods through schist bedrock. In
the 1940s, the tunnel was lined with 12
inch by 12 inch untreated vertical timbers
as structural members to increase the
tunnel and portal strength and stability
using a standard style of construction.
The north portal area of the Moody
Tunnel collapsed in June 2005 when a
high load on a south bound train with
a piece of equipment onboard struck
some of the supporting timber sets, requiring
the railroad to shut that section
down for three days.
The incident prompted the Moody
Tunnel demolition, which included
mapping the bedrock and conducting
rock-engineering studies to decide how
to stabilize it. The section of track just
north of the tunnel was perched on old
timber cribbing. The decision was made
by the railroad to blast more bedrock
along this section of the canyon wall to
make room for the safety realignment
and move the track off the cribbing.
What the railroad found was that
that as long as it was going to pull the
tunnel offline, it should also take advantage
of the opportunity to realign
the tracks through the curve, which will
be done during the fourth stage.
Operating in Alaska since 2004,
Advanced Blasting Services, one of
AGC’s newest members, has so far
completed blasting projects for about
40 clients, including the Deadhorse
and Barrow airports. The company
has a perfect safety record, Saunders
says, and in addition to explosives
engineering and blasting services,
offers quarry and pit development,
material production, roads, highways
and bridges, harbor and land development,
housing pads and utilitiy
trenches. It also provides assistance
in mine exploration, seismic activities
and vibration monitoring.
The Moody Tunnel demolition,
Saunders says, was particularly interesting
to the company because it included
Demolition charges cut through the wood and steel tunnel lining.
shooting down rock, timber and steel –
materials that all act differently – which
involved carefully planned timing so
that the different materials came down
according to appropriate intervals.
“The project went according to
plan, with no injuries, accidents or
damage, and it was on schedule,”
Saunders said, an incredible accomplishment
considering that the project
was considered to be dangerous.
Heidi Bohi is a freelance writer and
marketing professional who divides her
time between Anchorage and Arizona.