We have made methodological changes over previous versions of SNAMUTS and are gradually updating the cities based on these. We’ve started with the Australasian cities. A check on the pdf file name will confirm if there has been an update – it will be signified with the word ‘modified’ in the file name.
The changes are as follows:
A better estimate of actual journey times. Preferred journey paths, influencing the outcomes of the Betweenness and Resilience indexes, are now calculated with location-specific rather than network-wide average transfer time estimates, and also now contain a measure of average waiting time at first boarding. This procedure tends to better prioritise higher-frequency services over lower-frequency ones when determining the flow of travel opportunities across the network.
Betweenness measures are now capped at the capacity of a service. Travel opportunities that are unlikely to fit on a service offered anywhere along its path due to practical capacity limits are no longer counted in the betweenness index. This procedure aims to arrive at a more accurate proxy representation of actual travel flows along the network.
A new calculation applies to the global betweenness index, to better neutralise this measure for the size of the metropolitan area and thus make the results more comparable between metropolitan areas of different sizes.
A new scale applies to the resilience index. To reduce ‘statistical noise’ in the comparison of nodal and network resilience values over a timeline or between scenarios, resilience values now follow a scale from a positive 12 to negative infinite (previously 30 to negative infinite), effectively dividing the previous values by 2.5. The colour coding of resilience categories remains the same as in previous SNAMUTS versions.
The nodal connectivity measure is now based on internal calculations for average occupancy per mode. SNAMUTS now determines this measure from network-wide modal resilience figures rather than relying on the inconsistent and patchy external figures from transport operators in each case study city. This reform also establishes a more consistent standard for future scenarios and neutralises the effect of factors outside the land use-transport context on patronage, such as the collapse of public transport ridership in many jurisdictions during the COVID-19 pandemic.
A new scale applies to the nodal connectivity index. To reduce ‘statistical noise’ in the comparison of nodal connectivity values over a timeline or between scenarios, the previous scale has been divided by 5 in the modified tables and diagrams, while the colour categories remain unchanged. Hence, the threshold for a ‘red dot’ is now a nodal connectivity value of 20 (previously 100).
These modifications also affect the SNAMUTS composite index. While the composite index is primarily designed as a visual rather than numeric representation of accessibility quality, note that average composite figures should not be directly compared between the modified and the previous standard, and that distortions may occur when comparing colour categories on the maps between the two standards.
The changes are as follows:
A better estimate of actual journey times. Preferred journey paths, influencing the outcomes of the Betweenness and Resilience indexes, are now calculated with location-specific rather than network-wide average transfer time estimates, and also now contain a measure of average waiting time at first boarding. This procedure tends to better prioritise higher-frequency services over lower-frequency ones when determining the flow of travel opportunities across the network.
Betweenness measures are now capped at the capacity of a service. Travel opportunities that are unlikely to fit on a service offered anywhere along its path due to practical capacity limits are no longer counted in the betweenness index. This procedure aims to arrive at a more accurate proxy representation of actual travel flows along the network.
A new calculation applies to the global betweenness index, to better neutralise this measure for the size of the metropolitan area and thus make the results more comparable between metropolitan areas of different sizes.
A new scale applies to the resilience index. To reduce ‘statistical noise’ in the comparison of nodal and network resilience values over a timeline or between scenarios, resilience values now follow a scale from a positive 12 to negative infinite (previously 30 to negative infinite), effectively dividing the previous values by 2.5. The colour coding of resilience categories remains the same as in previous SNAMUTS versions.
The nodal connectivity measure is now based on internal calculations for average occupancy per mode. SNAMUTS now determines this measure from network-wide modal resilience figures rather than relying on the inconsistent and patchy external figures from transport operators in each case study city. This reform also establishes a more consistent standard for future scenarios and neutralises the effect of factors outside the land use-transport context on patronage, such as the collapse of public transport ridership in many jurisdictions during the COVID-19 pandemic.
A new scale applies to the nodal connectivity index. To reduce ‘statistical noise’ in the comparison of nodal connectivity values over a timeline or between scenarios, the previous scale has been divided by 5 in the modified tables and diagrams, while the colour categories remain unchanged. Hence, the threshold for a ‘red dot’ is now a nodal connectivity value of 20 (previously 100).
These modifications also affect the SNAMUTS composite index. While the composite index is primarily designed as a visual rather than numeric representation of accessibility quality, note that average composite figures should not be directly compared between the modified and the previous standard, and that distortions may occur when comparing colour categories on the maps between the two standards.
