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Date 09.10.2015

Wales Route

Management of Railway

Coastal Structures

Kevin Giles, Senior Asset Engineer

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North Wales – Mostyn Sea Wall

CNH3 – Chester and Holyhead Line

4th December 2013

Greater than 1 in 500yr storm event

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Cambrian Railway - Tywyn

DJP – Dovey Jcn to Pwllheli

03rd January 2014

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Cambrian Railways - Llanaber

DJP North of Barmouth

03rd January 2014

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Ferryside – St. Ishmaels Sea Wall

SWM2 – South Wales Main Line

03rd January 2014

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Coastal, Estuarial River Defences (CERDS)

• Coastal Assets covering a length of 34miles across Wales

• Largest number of assets within Network Rail

• Comprising a variety of construction types in various measures of condition including soft structures Holywell embankment, Ferryside sand dunes

• Subject to annual inspection regime

• Planned and reactive works arising from inspection or damage sustained during storm events

Situation on Friday 3rd January 2014

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Met Office - ‘Winds hit 80mph on the Welsh Coast on Friday 3rd Jan reaching storm or even violent storm force at points’

NRW - ‘Highest tides to hit the Welsh coast since 1997’

On Friday 3rd January 2014, the Welsh Coast was hit by a low pressure weather system consisting of high tides, large storm surge and strong Gale force 9 South Westerly winds resulting in extensive storm damage to coastal areas throughout the UK and in particular those coastal towns situated on the West coast of Wales.

Backing-up of river estuaries caused extensive flooding, leading to land saturation, which prevented / delayed normal drainage

Location and Swell Surge Map

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Swell surge: this map shows the

situation on Friday at 3pm where

large waves on a high tide struck

the west coast of the UK.

Contributory Factors to Storm Damage

• Climate Change - Sea Level Rise

• Natural Coastal erosion

- Lack of coastal defences, groynes etc.to protect the railway

• Requirement for a Pro-active Coastal Defence Strategy

- The beach area at Tywyn, Sandilands and Llanaber used to be dredged in the

Spring and Autumn. This was stopped 10 years ago, resulting higher and flatter

beach profiles, contributed to the extent of damage in this storm event.

- Culverts and leading ditches (many on land adjacent to the railway) require

extensive clearance as these are contributory factors to washout

• Prolonged wet weather

- Resulting in the surrounding catchment areas being saturated and unable to

accept further water.

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Main Sites Affected by the 3 January Storms

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Dovey Junction to Pwllhelli • Aberdovey sea defences

• Tywyn sea defences

• Llwyngwrill clay cliff

• Ffriog cliffs and sea defences

• Llanaber sea defences

• Harlech sea wall

• Afon Wen sea defences

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Levels of Service and Intervention Strategy

• Levels of service describe the key outputs Network Rail intends to deliver to its customers. Our levels of service (or asset management objectives) for the CERD assets are capability, safety and availability.

• Current management process provides assurance on condition of CERDs to inform a level of intervention but is it enough to fully achieve all three objectives

• Change of approach

• Coastal Estuarial Asset Management Plan (CEAMP)

• Delivery, JBA Consulting

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CEAMP Methodology

• Identification of the risks to rail assets protected by CERDs. The assessment of the hazards and threats associated with coastal processes, and draws upon the bow-tie approach for assessing risk.

• Analysis of the risks. The quantification of risk as a function of the probability of an event occurring and the resulting consequence.

• Evaluation of the risks. The determination and ranking of risk for each of the CERDs based on their exposure to coastal risks now and in the future including for the effects of Climate change.

• Management of the risks. The development and execution of the CEAMP based on the risk evaluation work.

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CEAMP North Wales

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Risk Identification and analysis

• The risk identification process took account of the hazards and threats due to structures that have been identified under the Business Critical Rules (BCR) programme

• This groups risk under three main hazard headings:

–Failure of the supported track;

–Unsafe environment for people

–Collision with failed infrastructure

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Risk Categories

Wave overtopping

Inundation

Coastal erosion

Assessment of available Risk Information

• Digital Elevation Models/LIDAR data; Used to estimate the elevation of key

structural aspects of CERDs (crest height, berm level etc.) or the elevation of any

railway infrastructure (the line, cess or cuttings etc).

• Flood maps and reports; which can support floodplain delineation and are

available for a range of return periods for defended scenarios, however typically are

only available for the 1 in 200-year return period for undefended scenarios.

• Extreme sea-level information; which are estimates of the level that the sea is

expected to reach during storm events of different return period magnitudes

between 1in 1-year to 1 in 1000-year events, available from a NRW/EA dataset

referred to as the Coastal Flood Boundary Dataset (CFBD)1.

• Extreme wave conditions; which are estimates of extreme offshore wave

conditions, such as wave height, period and direction, expected to reach during

storm events of different return period magnitudes.

• Erosion risk information; which estimates the risk of erosion to the coastline.

These maps are available from the National Coastal Erosion Risk Maps (NCERM)

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Climate Change Projections

• Provides estimates to the change in mean sea-level (and the extreme sea-level estimates provided in the CFBD dataset) based on present day climate conditions.

• Used to evaluate how these still water levels will change as a result of climate change through the lifecycle of a coastal asset.

• From the UK Climate Change Impact Programme as part of a dataset referred to as UKCP09 and contains sea-level rise estimates up to the year 2115 based on a number of carbon emissions scenarios.

• In line with standard practice for flood risk modelling projects, the sea-level rise estimates used in this study were based on a medium emissions scenario 2.

• E.g. While there is some spatial variation along the North Wales coastline in terms of sea-level rise projections, the general increase in sea-level for 2115 is 0.69m at Penmaenmawr:

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Bow Tie Analysis

The risks to the railway (resulting in failure of the

supported track) are dominated by the threats of coastal

erosion, wave overtopping and flooding.

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Coastal Risk Rating

• Our approach therefore was to combine the risks from these threats into an overall risk rating for each asset called the Coastal Risk Rating (CRR).

• A CERD asset management plan will typically deal with a number of individual assets along a frontage or even across a route (rock armour, sea wall, clay bund)

• Breaking down further it would allow comparison of the risks from individual assets within the frontage.

• Provides a holistic approach to asset management particularly in relation to SMP’s, NRW and LA plans and aspirations

• The probability of each threat occurring is a function of the factors given in the following matrices.

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Risk Evaluation and Prioritisation

High

Medium

Low

Interactive CEAMP Matrix

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Intervention

The decision on when to intervene in a particular asset or asset element, and the nature of this intervention, is a function of its:

• CRR

• Rate of deterioration

and

• The level of other qualitative risks such as safety

CERDs with a high CRR rating will therefore have a higher priority for maintenance, renewal intervention or other safety and operational management action than assets with a lower CRR

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Adoption of NRW/EA Condition hierarchy

• Adopted by Network Rail Wales Route for this Project

• A new hierarchy for NR CERD assets has a degree of

compatibility with the NRW/EA’s classification system and

we have adopted descriptions for the major and minor

CERD elements that closely mirror those used by the

NRW/EA

• Opens up the possibility of being able to share data on

condition and performance to the benefit of both parties.

• Makes it possible to adopt the NRW/EA’s 1-5 asset

condition rating system

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Investment Planning

The last stage in the risk management approach

Develop an investment plan that sets out for each defined intervention category the forecast expenditures over the short, medium and long term.

• Short term

Encompasses the detailed planning required to support the available funds for CP5.

• Medium and Long term

While an input to this, the CRR has greater applicability in setting the medium and long term plans which take into account the intervention prioritisation

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Next Steps

• Engage Contractor Input using PPM Principles

• Develop the Programme into 2 Phases

• Phase 1. Protecting todays Railway

Short Term

• Phase 2. Planning for Tomorrows Railway

Medium to Long Term

Protecting Todays Railway

Using the Coastal Risk Rating, Prioritise existing assets based on their condition and operational vulnerability.

5 Stages:-

1.Desk Top Study;- Prioritise sites and worst affected areas at each site, Identify SSSI and other Environmental issues

2.Site Visit:- Joint NR and Contractor to identify appropriate interventions, prioritise defects, use of Standard Detail Drawings, Repair Methodology

3.Detailed Planning, estimating and securing of Consents and Approvals.

4.Delivery and Quality Management

5.Review/Site Handover and Remarking of Asset Condition

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Planning for Tomorrow’s Railway

Using the Event Modelling of the Prioritised sites, consider feasible Interventions/Enhancements to improve Asset Resilience and Durability to Future Weather Events and Sea Level Rise as a result of Climate Change.

1.Identify options to improve or prevent infrastructure failure and provide high level order of magnitude estimates.

2.Undertake investment appraisals and NPV analysis on intervention options on a line of route basis with base case of do-minimum (i.e. prevent erosion failures).

3.Identify short-medium term interventions. Develop those improvement measures that can be funded within existing budget constraints.

4.Provide a strategic plan for the future Asset Management of Railway Infrastructure

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Timescales

Phase 1. Protecting Todays Railway

• Short Term Measures to maintain existing condition of assets and address minor defects that will offer quick gains and mitigate risk to current operational requirements

• Commence Prioritisation of Sites and Interventions, Year 2 CP5

Phase 2. Planning for Tomorrows Railway

• Medium to Longer Term Measures to address major repairs that can be encompassed within current CP5 budget availability and identify Improvements/Enhancements for the longer term Strategic benefit of the Infrastructure

• Commence Development of Strategic Plan, Year 2 CP5 through implementation late CP5, CP6 and beyond

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What level of resilience do we want?

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Cost of recovering Cambrian, North and South Wales Asset failures was £20million

What about improvements? (Long Term Resilience)

What happens if the ‘once in 200 years’ storm comes more often?

How do we balance the responsibilities of Network Rail vs local priorities and funding?

The Cambrian is a loss making line – doesn’t cover operating costs

How much are we willing to pay?

What if the railway protects towns and villages from flooding?

When should we suspend services?

What do travellers and tax payers expect