Climate Change, Landslides and Infrastructure Context[1] Times - - PowerPoint PPT Presentation

Safe roads, Reliable journeys, Informed travellers

Climate Change, Landslides and Infrastructure

Context[1]

• Times 13 October 2005 –

Roads and a stretch of the West Coast Main Line closed after heavy downpours – landslides blocked roads in Dumfries and Galloway.

Context[2]

• HA – 6000km of earthworks in England.
• NR – 10000km of earthworks in England, Scotland

and Wales.

• BW – 3000km of assets in England, Scotland and

Wales

• LA’s - ??
• Need to emphasise that new works are a very small

percentage of the asset < 0.5% per annum and age and condition of the assets varies considerably often related to construction methods used.

Context[3]

HA – currently 40 – 50 failures per annum with annual maintenance spend in region of £12-15 million. NR – approximately 400 incidents per annum with annual spend on remedial works of £100 million. BW – still undertaking inspections of 2400 assets but spend since 1998 of the order of £36million. LA’s – no data.. The majority of current slope failures are associated with overconsolidated clays.

Context [4]

• Climate Change and the Highways Agency TRL 2001
• The Changing Climate:Impact on the Department of

Transport 2003?

• The Department asked HA to review DMRB to carry
• ut assessment of standards to identify revisions

required in light of UKCIP’s scenarios.

• Key impact is deterioration of highway infrastructure.
• Embankments are at risk of both subsidence and

heave.

• Problems on rail network are expected to increase.

Ais Gill landslide (31/1/95) – Ultimate Limit state failure

31/1/95 Fatal Accident near Ais Gill (16.26 2H88 Carlisle to Leeds and 17.45 2H92 Carlisle to Leeds)

.

Flint Hall Farm

A34 Tothill

A10 Milton

Recent Experience

• Scottish Road Network Climate Change Study
• Scottish Road Network Landslide Study
• Both documents published in June 2005 and

available on website.

• Best current practice documents but are they

applicable elsewhere in UK?

Conclusions

• Rainfall is most important parameter linked to future

instability.

• Annual rainfall in Scotland and elsewhere? is

expected to show little change until 2020’s.

• Rain has potential to cause significant landslide

events and changes in groundwater levels reducing stability of cuttings.

• More concern related to surface-water drainage,

culvert design, flooding and increased run-off.

Recommendations

• It is possible that in winter conditions groundwater

levels may be higher than allowed for in the design of cuttings- no formal recommendations can be made without an appropriate climate change model being developed for this issue.

• It is not possible with the information presently

available to provide qualitative guidance on either groundwater levels or changes to rates of recharge to the groundwater body.

Precedent

• In 2001 significant winter rainfall events lead to a

considerable increase in the number of slope failures

• n the highway network in the South of England with

more than 60 separate incidents on HA roads and many more on other roads.

• Climate change or natural variation?

Summing Up [1]

• Little or no current action to address issue of climate

change related to slope stability?

• No need to consider changes until at least 2020?
• Relatively straightforward to design new earthworks

but what assumptions do we make and how do we justify cost?

• Major issue for all infrastructure owners relates to

existing assets with at least 20000km in UK – what do we need to do to protect assets?

Summing Up [2]

• Given that increased rainfall is main source of future

instability have we sufficient confidence in current models if indeed they exist?

• What type of increased rainfall has most impact i.e.

short duration storms or general seasonal increase?

• Storms are not new so what is going to change and is

it significant?

• What can we learn from other areas of the world

where such storms are common?

• Is better drainage the best and indeed the only

solution?

Thank you