We mostly use bart to travel to city area like San Francisco. This is because it is hard to find parking lot and more expansive to park a car in the city. However, one of the Berkeley students actually told me that you can park your car at the BART station during the weekend. The largest difference between the BART and MRT in Singapore is the frequency. Sometimes we wait for around 15 minutes if we missed the previous train. Besides, it is important to notice the length of the train. If it is a four car train, it will be quite short, and you will not be able to get on the train if you are at the very end of the station platform. Downtown Berkeley station is the nearest bart station from campus. It is a 20 minutes walk away from campus but you can take a bus to the bart station also.
UC Berkeley has a huge campus. You can always walk from one hall to another. However, if you are tired of walking, you can take the bus on campus also. AC Transit is available both on campus and out of campus. For Berkeley students, AC transit is free in Berkeley. However, you will need to pay for it in San Francisco.
Besides AC Transit, bear transit is also free for students on campus. However, since the bus frequency is quite low, most of us still walk around the campus.
You can use clipper card for almost all of the public transportation except the cable car which requires you to pay in cash. You only need to scan your card once when you get on the bus. You can top up your clipper card at the BART station. The clipper card is given to all Berkeley students. Hence, we do not need to purchase it.