Evidence review of road-space reallocation

Road space reallocation (RSR) involves the permanent reallocation of existing road space from general traffic to active or public transport modes, and can affect traffic, parking, cycle and bus lanes, and footpaths. ViaStrada undertook a review for NZTA of the New Zealand and international literature on RSR examined 30 case studies where the impact of permanent RSR interventions had been measured, in relation to changes in network vehicle-kilometres travelled (VKT). The review aimed to:

• improve knowledge of the impact that RSR has on network VKT
• quantify the overall network effects of RSR
• identify the factors required to successfully use RSR to reduce the VKT within a network. 

The research did not manage to clearly establish the impacts of RSR on network VKT, largely due to the absence of available evidence. The findings are therefore not strong enough to demonstrate the systemic effectiveness of RSR in reducing net VKT. However, the available literature contains some evidence that RSR interventions reduce road congestion overall, and change network-wide congestion. The authors caution that not all the studies providing this evidence were relevant to New Zealand, and more research was required to confirm these trends would also eventuate here. 

The review also found evidence of reductions in motorists’ mean speed, increases in active transport modes on roads where interventions have occurred, and improved road-user safety. When it came to the factors that helped achieve a change in network VKT, projects where multiple streets, or a key strategic link such as a bridge or tunnel, were affected by RSR interventions were found to be most effective. 

Projects that incorporated new walking and cycling facilities, improved pedestrian crossing facilities, and incorporated street landscaping measures or modal filtering elements (physical measures that prevent motor vehicles getting through) were also found to be effective, as were those where a traffic or parking lane was removed to provide more space for other road users. Non-physical factors, such as effective governance, political support and public engagement, also had a part to play, and the authors recommended best-practice measures for future RSR projects to help ensure their success.