Baseline Screening

A Baseline Screening Assessment was conducted to identify sections of the TRN with the highest exposure to present day climate hazards. By evaluating both hazard exposure and asset vulnerability, the screening assigned high-level risk scores to areas of the Scottish TRN to inform strategic prioritisation of adaptation measures across the network.

Building on the transport risks identified in the CCRA3, the baseline screening applied Geographical Information Systems (GIS) mapping to overlay climate hazard data with the TRN, enabling a spatial analysis of exposure and vulnerability across the network. Asset age and condition of road structures were also factored into the assessment to understand how structurally sensitive they may be to the impacts of climate change.

The baseline screening of climate risks is used to identify the areas across the network that are most vulnerable to different climate hazards under present day climatic conditions. This assessment facilitated the development of the TRAP through the identification of areas at higher risk due to higher exposure or local asset vulnerability. The results inform which parts of the network require the most attention with regard to minimising future disruption and cost associated with severe weather-related disruptions, and where adaptation actions can be applied at scale at multiple locations. A detailed climate screening report has been developed for internal use.

Validation for the independent baseline screening was supported through internal stakeholder engagement, analysis of our incident database, and a review of previously identified vulnerable structures. Figure 2 shows the outputs of the Baseline Screening for the TRN as a whole. As shown, surface flooding, landslides and river flooding were amongst the highest scoring risks, with assets such as road surface and structures demonstrating high levels of exposure and vulnerability.

Figure 2: Baseline climate risk inputs and result score card

Hazard Exposure

  • Surface Flooding
  • River Flooding
  • Coastal Flooding
  • Landslides
  • HIgh winds
  • Cold Spells
  • River Scour
  • Heatwaves

plus:

Vulnerability

  • Age of road surface
  • Bridge and structures condition 

equals:

Baseline Screening Risk Score

  • Surface Flooding (high)
  • Landslides (high)
  • River Flooding (high)
  • River Scour (medium)
  • Coastal Flooding (medium)
  • Cold Spells (medium)
  • High winds (medium)
  • Heatwaves (low)

From the risk screening outputs at the TRN level as a whole, areas exposed to several climate hazards were assessed to identify specific potential vulnerable locations across the network. Two examples of the risk scores for eight climate hazards, considering hazard, exposure, and asset vulnerability, assessed across 2km side ‘hexes,’ are presented in Figure 3 below.

Assessment Factors:

  • Hazard: The potential occurrence of a natural or human-induced physical event or trend that may cause loss of life, injury, or other health impacts, as well as damage and loss to property, infrastructure, livelihoods, service provision, ecosystems, and environmental resources.
  • Vulnerability: propensity or predisposition to be adversely affected.
  • Exposure: presence of people, livelihoods, species or ecosystems, environmental functions, services and resources, infrastructure, or economic, social, or cultural assets in places and settings that could be affected.

Figure 3: Example of trunk road network baseline climate risk screening multi-hazard score in Skye

Risk and risk score (Cuidrach)

  • Extreme heat (Low)
  • Cold Spells (Very low)
  • River flooding (low)
  • Surface water flooding (low)
  • Coastal flooding (Very low)
  • River scour (Very low)
  • Landslides (Low)
  • High winds (Medium)

Risk and risk score (Toravaig)

  • Extreme heat (Low)
  • Cold Spells (Medium)
  • River flooding (Very low)
  • Surface water flooding (Very low)
  • Coastal flooding (Very low)
  • River scour (Very low)
  • Landslides (Medium)
  • High winds (Very High)