There are many buses leaving regularly for the Terracotta Warrior museum in front of the Xi'an bus station (east to the train station, outside (in the north) the city walls).
Bus 306 (Chinese bus green 5) leaves from the lot in front of the train station and will take you to a parking lot right in front of the museum site in about an hour (it can take up to 90 minutes in case of traffic jams). A one-way ticket costs ¥7 (pay on the bus). It also stops at several other tourist attractions along the way, e.g. the hot springs. Make sure you don't make the mistake of going to the bus station on the inside of the wall near the train station. That's were there are touts with signs saying bus 5 and bus 306, trying to hustle you onto their private bus. Although they do take you to the destinations, you are forced to go to visit attractions you might not want to go to.
Small buses which are used by the locals (e.g. number 914). These buses will also take you to the Museum however they go through local small roads (no highway express like bus 306) therefore it will take longer to arrive. Not a bad trip if you want to see the local bumpy rural roads.
Most hostels and hotels run tours to the warriors with an English speaking guide. These aren't necessarily better, be prepared to spend a good portion of the day (as with any Chinese tour) visiting "terracotta factories," "museums", "Chinese medicine shops", and other tourist traps. But, you will get to your destination without dealing with the bus (the warriors are quite far outside of town) and not all of the public buses that go there are legitimate.
Like everywhere else, taxi-drivers in China are both lovable and detestable. In Kunming, we saw a convoy of `loving heart’ taxis ferrying passengers supposedly on welfare for an outing. Such a sight gives us a good impression of the taxi-drivers who are doing a charitable act for society. But elsewhere in Xian, we met a taxi-driver who was out to squeeze money from an ignorant tourist. He was supposed to turn on the meter when we got up his taxi intending to go to the Airport. `It’s a long way,” we don’t go by the meter. “RMB 120” which we bargained to RMB 100. “Okay,” he said, “Believe me, I’ll not accept anymore than that” But on the way, he mentioned that I had to pay for the road toll to the Airport – RMB10, which we agreed and RMB10 for `waiting’, which we rejected. The Airport, however, wasn’t that far away. The road toll was in fact RMB 5 for entering the road leading to the airport, but the driver quickly explained that another RMB 5 was for leaving the road from the airport. Metered taxis are, at their worst are better than pirate cars posing as taxis although they could be cheaper. I was told that they are not insured and tend to take you places, which you have not asked for. At the time of our visit, March/April 2005, the turn-on charges for the taxis at various cities are:
Suzhou –RMB5 (Avoid taking private cars or taxis or accepting offers from `brokers’ waiting outside the train station. Walk further out to a queue where `regulated’ taxis are picking up passengers from.)
Shanghai –RMB10/18 (Airport mini-bus taxis are available for tourists with large number of luggage. The turn-on charge is RMB18. I believe the choice is ours to take the normal taxis)
it's convenience to take around in Xian by taxi. It could be take you about $1US or so. Taking the bus of coure is vey cheap but sometimes crouded. If you are not in hurry and want to have speicial and easy feeling, try the pedicab.