Flow was recently responsible for developing a Speed Management Plan for Auckland Transport, in 2023. We undertook considerable research on the effects of lower speed limits, looking at international examples of changing limits from 50 to 30 km/h (or from 30 to 20 mph).  Primarily this focused on reductions in road crash casualties, but also considered the expected co-benefits of reduced noise and reduced CO2 emissions, and the potential increase in walking and cycling related to a lower speed traffic environment.  Our work on this project informed policy decisions regarding the adoption of lower speed limits across Auckland.  Using knowledge gained from our research, we completed economic evaluation of four options which involved different spatial coverage of lower speed limits, which included quantifying benefits from reduced crashes, reduced vehicle operating costs and reduced CO2 emissions. In addition, we created clear and concise messaging to assist in the public and stakeholder consultation and we also developed and evaluated a toolkit of engineering interventions for reducing speeds.

Further details, including our report on the economic effects of the project, can be found here