From LAX Airport to Amtrak Union Station
All Amtrak trains serving Los Angeles depart from Union Station. The best way to travel between the airport and the Amtrak station is by the FlyAway express bus. Express buses are fast and run rather frequently, and the entire journey (including all walking) takes approximately an hour. Beware that private shuttles run less frequently than the FlyAway buses do, and so you are not going to save any time by taking a shuttle despite paying at least 3 times as much as the cost of a FlyAway ride. Moreover, FlyAway buses run at all times, and they use separate "high-occupancy vehicles" lanes on freeways.
FlyAway buses stop at all LAX terminals. To get to a FlyAway stop, exit from any terminal on the "Arrival" (lower) level and locate a green sign "FlyAway, Buses, and Long-Distance Vans" above the island curb. The walk from any gate to the stop takes about 10 minutes.
FlyAway buses are large blue coaches properly marked as "FlyAway". Beware that there are several FlyAway routes serving the airport, and you need only the one that goes to Union Station (check the destination signs on the arriving bus to make sure you are taking a correct one). Buses on the Union Station route depart every 30 minutes on the hour and half hour from 05:00 to 01:00 and every hour on the hour from 01:00 to 05:00. The departure times are shown for Terminal 1; all other terminals are served in numerical order after Terminal 1, so that buses stop at Terminal 8 about 15 minutes after the scheduled time.
The fare is $7. You will need to pay it upon exiting the bus, not upon boarding it. Travel time from LAX to Union Station is about 45 minutes, but it may take up to an hour during rush hours on weekdays.
Once you arrive at Union Station, first pay your fare at the kiosk next to the bus stop (cash only). Then follow the descending path in the middle of the bus island. This path leads to a wide pedestrian tunnel, which provides access to the train platforms and the station building. The entire walk takes 2 or 3 minutes.
The total travel time from LAX to Union Station should be about an hour including all walking and riding the bus (about 1 hour 15 minutes if you are traveling during rush hours on weekdays). Do not forget to factor in the wait time, which is less than 30 minutes during most of the day. Typically, it is safe to have 1 hour 30 minutes to make this connection between the airport and the Amtrak station; however, you may want to allow 1 hour 45 minutes during rush hours or other busy periods.
The FlyAway service operates at all times, and so there is no last bus to miss.
If you still have any questions, feel free to email me (no phone calls please).