Table 1.

Description of urban metrics quantifying patterns of population, road network, land cover and geographical characteristics

Theme	Urban characteristic	Urban metrics	Data source	Potential health related benefits	Potential health related concerns
Population	Population density	Population density (pop/km2): total city population over city area in square kilometres	ONS, Census 2001	High population density: • easy to walk/cycle • increase of physical activity [15]	High population density: • spread of infectious diseases • elevated air pollution levels • potential loss of green space • social stress
Road network	Walkability of cities	Minor road density (km/km2): length in kilometres of minor roads and B roads over city area (km2)a	OS, Meridian 2	High minor road density: • easy to walk/cycle • increase of physical activity [15]	High minor road density: • elevated pollution levels • higher road traffic noise levels
	Connectivity of road network	Junction density (N/km2): number of A roads, B roads and minor road junctions over city area (km2)a	OS, Meridian 2	High junction density: • easy to walk/cycle • increase of physical activity [15]	High junction density: • elevated air pollution levels • higher road traffic noise levels • increased number of road traffic accidents related to road junctions
	Urban sprawl	Population within 100 m of major roads (%): proportion of postcode headcount population within 100 m of A roadsa	OS, Meridian 2; ONS, Census 2001		High population density close to major roads: • higher noise and air pollution exposure across city population • less likely to walk/cycle and reduction in physical activity [27] • increased number of road traffic accidents related to higher speed
Land cover	Land cover mix	Shannon’s diversity index (SDI) [31]: $H=-{\displaystyle \sum _{i=1}^s{p}_i\mathit{ln}{p}_i}$ where p i is the proportion of land cover i relative to the total number of land cover classes	CEH, Land Cover Map 2000; EEA, CORINE Land Cover 1990 (vs 12/2000)	High land cover mix: • easy to walk/cycle • increase of physical activity [15] • less car usage • lower air pollution levels	High land cover mix: • residential areas potentially close to polluted areas
Geographical characteristics	Terrain	Altitude range (m)	OS, Land-Form PANORAMA	Hilly terrain: • increase in physical exercise if walking or cycling	Hilly terrain: • Less likely to walk/cycle

^aRoad classification in the UK is classified by the Department of Transport (DfT) as follows: A roads connect areas of regional importance, B roads connect places of local significance and minor roads are roads without classification by the DfT, mostly local roads intended for local traffic [28]