An advisory shoulder, also known as a 2-1 (‘two minus one’) lane layout is a single with shoulders on either side for cyclists and e-scooter riders in urban areas, and also pedestrians and equestrians in rural areas. When two vehicles meet, both drivers must pull into the shoulder to pass after giving way to any user of the shoulder. During such an encounter, a driver must possibly slow down to cycling speed if the cycle lane is already in use. Such concepts are common in some countries and used in both urban and rural contexts. A collection of North American case studies can be found in Advisory Bike Lanes in North America(external link).
In urban contexts, advisory shoulders are generally used with a 30 km/h speed limit. In rural areas, speed limits of up to 60 km/h are used. In both environments, this layout only works with a low rate of encounters by drivers.
The use of broken yellow lines may be necessary in an urban setting to prevent parking in the shoulder.
Note that, while the initial advisory shoulder trial in New Zealand was controversial, the researchers recommended that the layout may be suitable in other locations. Road authorities wishing to implement this treatment would have to apply to the Waka Kotahi NZ Transport Agency to conduct another trial.
