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Table 1 Performance metrics and recorded effects

From: Introducing system interdependency into infrastructure appraisal: from projects to portfolios to pathways

Metric Description [assets included]
Environment Air quality NOx and PM10 emissions generated or negated by individual development or required supporting infrastructure [airport landing and take-off; additional electricity required/negated; road demand from airport].
Quantified according to infrastructure demand/operation levels and predicted emissions (Highways Agency (2007) and European Parliament (2007) for buses and cars, Department for Transport (2011b) for electricity, (AMEC 2014a) airports). Valued based on marginal abatement cost avoidance approach (Interdepartmental Group on Costs and Benefits, Air Quality Subject Group 2013).
Carbon dioxide emissions Carbon dioxide emissions generated or negated by individual development or required supporting infrastructure [airport landing and take-off; additional electricity required/negated; road demand from airport].
Quantified according to infrastructure demand/operation levels (Department for Transport 2011b; AMEC 2014b) and valued according to European Trading Scheme projections (Department for Transport 2011b).
Habitat Habitat land lost/gained due to development [all assets].
Quantified according to predicted landtake (Foster+Partners, Halcrow, Volterra 2011a) and land designations (Natural England 2014). Valued according to willingness to pay for conservation (Willis 1989), using UK Water Company multiplication factors.
Landscape and visual amenity Amenity value of land lost/gained due to development [all assets].
Quantified according to predicted landtake (Foster+Partners, Halcrow, Volterra 2011a) and valued according to willingness to pay for preservation (Entec 2004).
Noise Noise impact on local population caused by individual development or required supporting infrastructure [road, rail and airport].
Quantified through comparison with similar infrastructure assets (Department for Food and Rural Affairs 2012; Civil Aviation Authority 2012) and population projections (Hall et al. 2012). Valued according to hedonic pricing for quiet (Department for Transport, 2011b).
Water quality Degradation/improvement of water quality caused by individual development or required supporting infrastructure [barrier].
Quantified accord to conservative estimate of degradation from medium to low quality. Valued according to willingness to pay for water quality improvements (Georgiou et al. 2000).
Service Utilised capacity User value derived through provision of service (assumed to be half of revenue created) [rail, airport and electricity generation].
Quantified according to air passenger demand projections (Department for Transport 2011a) limited by asset design constraints (Foster+Partners, Halcrow, Volterra 2011a) and assessment of modal use of surface transport. Valued through ticket/utility prices for surface access and electricity (Transport for London 2013; Department of Energy and Climate Change 2011) and through predicted landing fees and ‘additional revenue’ for the airport (Foster+Partners, Halcrow, Volterra 2011a).
Congestion or reliability Value of time lost or gained due to capacity constraints of infrastructure provided [road and airport].
Quantified according to predicted congestion for road types used (Department for Transport 2011b) and current delay at Heathrow (Civil Aviation Authority 2013). Valued according to willingness to pay for time savings (Department for Transport 2011b).
Physical protection Asset protection provided by the development under extreme conditions (weather) [barrier].
Valued according to expert estimation as part of the TE2100 project (Environment Agency 2009) for the barrier.
Social Safety Injuries created or avoided through everyday provision of infrastructure service (user and employee accidents) [road and airport].
Quantified through historic accident rates (Department for Transport 2011c; Health and Safety Executive 2012) and valued through willingness to pay to avoid injury (Department for Transport 2011b).
Security Injuries created or avoided through provision of infrastructure under extreme conditions (weather, terrorism) [barrier, airport].
Quantified according to expert estimation as part of the TE2100 project (Environment Agency 2009) and valued through willingness to pay to avoid injury (Department for Transport 2011b). Terrorist threat quantified and valued through comparison with historic events (University of Maryland 2012; Institute for the Analysis of Global Security 2003).
Financial Cost Cost of implementing infrastructure (capital, operational and maintenance costs) by individual development or required supporting infrastructure [all assets].
Quantified according to proposal documentation (Foster+Partners, Halcrow, Volterra 2011a).
Revenue Gain or loss from provision of services (split with capacity effect) [rail, airport and electricity generation].
Quantified according to air passenger demand projections (Department for Transport 2011a) limited by asset design constraints (Foster+Partners, Halcrow, Volterra 2011a) and assessment of modal use of surface transport. Valued through ticket/utility prices for surface access and electricity (Transport for London 2013; Department of Energy and Climate Change 2011) and through predicted landing fees and ‘additional revenue’ for the airport (Foster+Partners et al 2011b). Airport revenues also include sale of redeveloped Heathrow site.
Tax implications Gain or loss to tax from implementation of development [road, rail, airport and electricity generation]. Quantified according to current income tax and national insurance and duty rates for petrol and rail tickets, with demand estimated via to air passenger demand projections (Department for Transport 2011a) and assessment of modal use of surface transport.
Employment Salaries and unemployment benefit generated or negated by development [rail, airport and electricity generation]. Quantified using average salary data (REED 2012) and current unemployment benefit rates.
  1. Further detail on data sources provided within the Additional file 1 .