Safety and efficiency benefits of implementing zip merge treatments in NSW

Merging has long been considered an issue for many road users. Motorists exercising their right of way and not allowing vehicles to merge across in a traditional ‘give- way’ merge has influenced road authorities to adapt. This has lead to the development of the zip merge system. A zip merge does not contain linemarking to separate vehicles throughout the merge and gives no priority to either vehicle. Instead, a ‘one-for-one’ approach is adopted, where motorist are encouraged to allow one vehicle in the adjacent lane to merge in front of them. In New South Wales, zip merging is allowed at all merge sites up to 80km/h. Currently most states around Australia are experiencing a transition period, which is seeing the phasing out of traditional merges, to be replaced by zip merges. Design standards, including signposting, delineation and merge length available vary throughout Australia and around the world. Throughout this report, various standards are investigated in order to highlight potential safety and efficiency benefits of the zip merge system. Along with design standards, different road rules exist depending on the merge system adopted. Alternating rules on vehicle priority can result in distinct driver behaviour, ultimately impacting on safety and efficiency. Research shows when used correctly, the system provides benefits for both safety and efficiency. Data collection involved investigation into how zip merges are currently performing. This was achieved through analysing video footage recorded at a number of zip merge sites in the Hunter Region of NSW. The observations looked at blinker and brake usage, the point where drivers were merging, along with general driver behaviours and interactions. It was found that blinker and brake usage is generally quite low (20% and 2% respectively). It was also found that drivers are utilising the available merge length (96% merged inside the taper) and displaying good driver behaviour (being courteous to other drivers). Utilising the length of merge available minimises merge angles between adjacent vehicles, which can potentially lower the severity of a crash. Utilising the entire merge also is an important factor, as it provides drivers more time perceive to and react to any situation requiring evasive manoeuvres. Standards Australia currently suggest to use zip merges in speed zones of up to 80km/h. In NSW there has recently been a number of safety barriers installed near on-ramps on freeways, suggesting that give-way merges contain considerable deficiencies even on high speed roads. The benefits of zip merges discussed throughout this report indicate that further investigation into freeway applications should be pursued. With an increasing investment into driver education and awareness programs, along with adopting the zip merging system on all road networks, it is likely that there would be a reduction in merge related crashes.