Highways Agency Annual Report and Accounts 2011-2012

Summary of our Performance: SECTION 2
Case Study:
Electricity used to
strengthen A21 road
embankments
The technique, known as electroosmosis,
delivers significant
environmental advantages and
avoids the need for restrictions
on the road while work is
being carried out. Traditionally,
embankment strengthening
involves clearing the slope
of vegetation, and requires
lanes to be closed on adjacent
carriageways. Electro-osmosis
avoids both of these, and uses an
electric current to strengthen the
soil in the slopes. With the new
technique, a small crawling rig
installs anodes and cathodes into
the ground around the existing
trees on the failed embankment
and an electric current is applied
over a period of weeks. This
removes moisture from the soil,
hardening and strengthening it
around the electrodes which are
then grouted to form conventional
soil nails.
Wiring the anode
The new technique did not
involve any excavation or lane
closures and most of the existing
vegetation was kept. This meant
Cables in place between the trees
the carbon footprint was lower
and we caused less disruption to
road users.
Electro-osmosis: a small crawling rig installs anodes and cathodes into the ground
at sub-tier level providing cost,
quality and consistency benefits.
Internally the Agency is reviewing
its procurement processes with
the aim of reducing time, resource
and supplier costs during the
tendering process.
Continued use of
managed motorways
Managed motorway schemes
are designed to deliver additional
capacity and reduce congestion
without the need for road
widening. The hard shoulder is
opened to traffic at peak times
Managed motorways help ease congestion
to ease congestion and speed
limits are varied according to the
volumes of traffic. Drivers are
kept informed through overhead
signals and gantry mounted signs.
Managed motorway technology is
currently operating successfully on
the following sections of motorway:
• M42 between junctions 3a and 7
• M6 between junctions 4 and 5
• M6 between junctions 8 and 10a
We are changing the framework
for how future managed motorway
schemes will operate. We have
produced a design where the hard
shoulder is converted to a running
lane for traffic on a permanent
basis. This new design is quicker
and cheaper to build and operate.
Highways Agency Annual Report and Accounts 2011-12