Congestion Report 2020Citywide congestion index results
| City | Excess Time Index | Excess Uncertainty Index | |||
|---|---|---|---|---|---|
| 2019 | 2020 | 2019 | 2020 | ||
| Sydney | 1.000 | 0.973 | 1.000 | 0.895 | |
| Melbourne | 1.000 | 0.932 | 1.000 | 0.694 | |
| Brisbane | 1.000 | 0.978 | 1.000 | 1.061 | |
| Adelaide | 1.000 | 1.006 | 1.000 | 1.093 | |
| Perth | 1.000 | 0.986 | 1.000 | 0.069 |
Four of the five cities experienced reductions in the city-wide mean excess time index due to reductions in commuter traffic during COVID (Figure 1). In particular, the reduction or elimination of morning and, to a lesser extent, afternoon peaks during initial lockdowns between March and June 2020 accounted for most of the reduction. Perth, Brisbane and Sydney saw falls of between 1 and 3 per cent and Melbourne, which experienced its second lockdown through the winter of 2020, had a larger reduction of 7 per cent. However, most routes that experienced pronounced reductions in April 2020, when lockdowns were first introduced, had returned to comparable levels of congestion by September 2020.
Adelaide experienced a slight increase in freight vehicle congestion, as measured by the mean excess time index. COVID-related lockdowns likely did not produce a significant reduction in METR for Adelaide because the routes chosen, only one of which is a motorway, did not exhibit the same pronounced morning and afternoon peaks as in the other cities in 2020. This means that the absence of commuter traffic could not have the same effect.
The mean excess uncertainty index also declined between 2019 and 2020 in Sydney, Melbourne and Perth, with the most significant declines in Sydney and Melbourne (see Figure 2). Adelaide experienced an increase in the mean excess uncertainty, which is consistent with the direction of change in the mean excess time index in Adelaide. Finally, the mean excess uncertainty index increased in Brisbane between 2019 and 2020, whereas the mean excess time decreased over the same period, which implies that averaged across all Brisbane routes, mean travel time decreased, but travel time uncertainty increased between 2019 and 2020.
Across routes within individual cities, the changes in mean excess time and uncertainty varied and even changed between directions.
It should be noted the city-wide METR and MEUR indexes, and the METR and MEUR for individual routes, weight all hours in the day equally. This means that were the industry and its clients to shift journeys into more congested parts of the day the measures would not be significantly affected even as congestion experienced by freight vehicle increases. This is to try and limit the measure to factors largely outside the control of participants in the industry – most urban traffic congestion is due to passenger vehicle traffic, freight vehicles comprise a small minority of total urban traffic volumes. However, since most congestion occurs in daylight hours, which is also when the majority of urban freight vehicle operations occur, the magnitude of the measures and the magnitude of increases and decreases year to year would be larger if METR and MEUR were weighted by freight vehicle traffic volumes.