Grenoble has four ways of getting around if you don't have a car: taxi; walking; a bicycle; and TAG, the city's public transportation network. TAG is run by a corporation called SEMITAG (Système Mixte de Transports en Commun de l'Agglomeration Grenobloise) and you can visit them at http://www.semitag.com or you can avoid their horrid website and finish reading this dang writeup!
TAG consists mostly of 35 bus lines that wind through the city and the suburbs of Echirolles, Eybens, St. Egrève, Varces, Domène, Claix, Le Pont de Claix, Seyssins, Seyssinet-Pariset, Fontaine, St.-Martin-d'Hères, Gières, La Tronche, Meylan, St.-Martin-le-Vinoux, Corenc, Poisat, Bresson, and Murianette. These busses typically run from approximately 5:00 AM to 9:00 PM, with abbreviated schedules during school vacations, Saturdays, Sundays, and holidays. On Thursday, Friday, and Saturday evenings, there are four altered bus routes that run from 9:00 PM to midnight. This service is called Noctibus, and they have security guards to prevent non-ticketed passengers from boarding the bus.
TAG busses are typically manufactured by Heuliez or Renault and exist in at least four different appearance, seating, and length configurations. Some of them have built-in ramps for accomodating disabled passengers, air conditioning, and enforced pop music.
In addition to the busses, TAG operates two tramway lines. The trams run later than the busses during the week; every night they run until midnight and sometimes after. These streetcars are manufactured by Alsthom Francorail. They exist in two configurations (differentiated mostly by age) and they all have built-in ramps.
To ride a TAG vehicle, you must have a valid ticket. You can buy one from the bus driver with cash or the billetterie at each tram stop with coins or a Carte bleue. A ticket is good for one hour after the first time you validate it. During the day, it is very easy to board a TAG bus or tram without a valid ticket. There are no physical means of preventing from boarding. However, a controle may occur at anytime, and if you are caught without a ticket, you will receive a hefty fine! Linca, who lives in Grenoble, tells me that bus drivers have started checking all passengers for passes before boarding.
The TAG network is augmented by by the VFD autocar service, which is operated by the department of l'Isère. On certain VFD lines, you can use your TAG ticket to get even farther outside the city. You can also use your TAG ticket to take SNCF TER trains among the train stations in Grenoble proper, Saint Egève, and Gières.
All TAG buses run on either biodiesel or propane. The trams are electric. | 
