It goes uninterrupted all round the clock on Carnival days. It is OK on Carnival days and leaves you within 30-40min walking distance. The station where to get off depends whether you want to arrive on the side of the odd- or the even-numbered sectors.
Get off at “Praça Onze” station. Once outside the station, turn twice to your right and then walk straight ahead. For sectors 10 and 12, take Rua Carmo Neto and walk on to Av. Salvador de Sá. You will see the Sambodromo soon.
Get off at “Central” station. Keep walking following the crowd until the Sambodromo, passing the schools’ floats and Samba Land.
Best to hail one on the street as timing the traffic is impossible on Carnival days. Rates are higher than normal and they will let you off within reasonable walking distance from the gates. Tell the driver in advance your sector number and establish the price.
On Parade days, there is an extra charge to leave the Sambodromo, too.