A bus or van, for example:HOV
[DOC] [TLE] HOV (Carpool) Lanes | FAQ - Metro [PAR] HOV lanes enable those who carpool or ride the bus to bypass traffic in the .... 
function (for example, roadside assistance and emergency service vehicles, and
... [DOC] [TLE] Potential Impact of Exempt Vehicles on HOV Lanes: Chapter 2 [PAR] Aug 2, 2013 ... Table 1.