Photos

Unlike on the toll-free Californian highways, there are no reserved Carpools lanes on the toll-paid Portuguese highways.
The Portuguese highways have the Via Verde ("green lane"), which are reserved lanes to pay on the toll plazas.
This smart system works with a small transponder* placed on the vehicle (somewhat like the aircrafts IFF*), so that you don't have to stop at the toll booth. As the vehicle approaches, the toll system identifies it by means of the transponder. Then, automatically, the value of the toll is transfered from the vehicle owner bank account to the Via Verde company bank account.
The Via Verde system is also used at parking plots and gas stations.
In this photo you see the toll plaza of 25 April Bridge, in Almada, south of Lisbon. As you see on top of the toll booths, there are 16 lanes; four (the green, also marked on the asphalt) are those reserved for the Via Verde; three (yellow) are for a special discount card; the others are for normal payment (cash or bank debit card).
Don't be misled by the 16 lanes and payment booths; the highway (and the bridge) has only three lanes, each direction. And this is no rush hour at all; this was shot a Saturday at noon. In rush hours of weekdays the traffic simply gets stuck, as thousands of cars converge to the bridge three lanes.
Location in Wikimapia: 38.6759451, -9.1740131.
É pena em Portugal só haver faixas reservadas (Via Verde) para pagar. Na Califórnia as auto-estradas, em portagens, têm faixas reservadas (Carpools) mas é para veículos com mais ocupantes.