Climbing lane

A climbing lane, crawler lane (UK^[1]), or truck lane, is an additional roadway lane that allows heavy or underpowered vehicles to ascend a steep grade without slowing other traffic. They are typically used by large trucks or semi-trailer trucks, which go uphill more slowly than they travel on level ground. They are often used on major routes such as motorways and interstate highways.

A more modern variation^{[citation needed]} is to keep an existing lane for slow traffic and make the additional lane a passing lane. This keeps slow traffic in the slowest lane even if drivers neglect to change lanes, while allowing drivers who wish to pass the choice of changing lanes to do so.