Scottish Road Network Landslides Study - University of Glasgow

RECOMMENDATIONS
Early Opportunities
6
EXECUTIVE OVERVIEW
A number of areas of perceived high hazard were identified at the Project Workshop. The
lengths of the road and the slope lengths they involve are substantial. Accordingly, it is
considered unrealistic to undertake suitably prioritised further evaluations at this stage. The
proposal is for the outputs of the GIS-based assessment to be used to corroborate the
identification of the localities identified at the Project Workshop and, in addition, as a
validation tool for the site specific assessment methodology.
In the meantime it is important that maintenance and construction projects currently in design
take the opportunity to limit any hazards or exposure by incorporating, where suitable,
measures such as higher capacity or better forms of drainage, or debris traps. Peer group
consultation in the form of the involvement of the Overseeing Organisation and its
Independent Geotechnical Checker, the corresponding specialists within the Operating
Companies, design organisations or other appropriate organisations is an essential part of this
process.
In the realm of minimising the potential impacts of debris flows on the network, some
retargeting of maintenance actions could be productive. The checking of gullies, ditches and
catchpits, with a wider view than that of merely keeping the roadway itself clear of water,
could be undertaken as part of regular inspections. Where ineffectiveness of the drainage
system, or underperformance under updated drainage criteria, is suspected, this should be
considered in conjunction with the inspection regime for the roadside side slopes and
remedial action addressed via an appropriate structured asset management plan. Additionally,
critical review of the alignment of culverts and other conduits close to the road ought to be
carried out as part of inspection and reporting procedures.
Certain monitoring measures are already under consideration – for example, the installation
of a rain gauge in the A83 Rest and be Thankful area, where debris flows are generally small
but relatively frequent, potentially yielding more comparable data in a short time frame. The
use of any such data gained, in conjunction with longer-duration data available from the
Meteorological Office, needs to be managed appropriately to serve a worthwhile and
consistent function. At a later stage, informed selection of locations for discrete placement of
additional rain-gauging facilities could be productive, and should be considered in the light of
experience of managing the information from current sources.
An important action which could be introduced on an early basis is bringing NADICS into the
management loop with regard to route advice when weather conditions conspire to create
situations where sections of the network might be considered ‘at-risk’.
Study 1, Part 2
The initial stage of Study 1, Part 2 will be to develop the methodology for the assessment of
hazard and exposure to provide a hazard ranking, together with the selection of an appropriate
management approach. The second stage will be to test the methodology before applying it
more widely to the trunk road network.