For many people, the 101 or 280 commute from the city to the south bay or vice versa becomes hellish, especially complemented with the difficulty of finding parking in the city.
The caltrain is a great alternative if you're simply trying to catch dinner in the city or plan on going out to the clubs or bars. The caltrain is the only mass transit system which allows you to drink aboard. People should beware though that the last caltrain to leave the city is midnight so late-night clubbers will have to either find a place to stay over night or find another alternative to come back home to the south bay. There are also several incentive programs for weekday commuters that Caltrain offers in order to support the state's clean air environmental programs. These usually result in free fare for several days of the month.
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