342 - Before 1999, 342 used to be lines 33B and 33C. Since then. service used to be every 30 minutes with service in two directions. Later cuts reduced service to one direction every hour. Ridership was never high and SamTrans wasn't able to boost ridership significantly after the opening of the BART station in Millbrae.
DX - Used to be 1F before 1999. It brought commuters from Pacifica to San Francisco. Bus riders in the area prefer a one-seat ride rather than a slower and more expensive transfer to BART. Express bus from Pacifica to Colma will still be available as line 118 (formerly CX). If you refuse to ride BART because of financial or other reasons, it is possible to ride 118 to Colma and transfer to line 391 to San Francisco. The fares will be lower but the ride will take longer.
FX - Used to be 47F, 48F, and 49F, which have different alignments in Foster City before 1999. It brought commuters from Foster City to San Francisco, which unlike other routes, actually stops north of Market Street. SamTrans decided to cut the route anyway despite the fact that it is the most productive among the express bus routes and that Foster City is not served by BART or Caltrain. In an attempt to reduce the impact, SamTrans instead will institute line 359, which follows the same alignment in Foster City but will go to Millbrae station. Passengers from there on will have to transfer to either BART or Caltrain.
SamTrans thinks it will save the agency money, but riders that switch from FX to 359 probably will contribute almost no revenue to SamTrans. Currently, FX riders pay $144 for a monthly pass. If they switch to BART, they can ride SamTrans free with BART Plus tickets ($21-23 more per half month). If they switch to Caltrain, they can ride SamTrans free with Caltrain monthly pass two zones or more ($112.75).
MX - Used to be 19F. SamTrans consultants recommended to cut the route 10 years ago citing competition with Caltrain and now BART.
NX - Used to be 41F. SamTrans consultants recommended to cut the route 10 years ago. Redwood Shore, like Foster City, is not served by either BART or Caltrain. If SamTrans had the planning foresight, it could've provided reverse commute service (similar to what Bauers is doing now in other areas) for San Francisco employees who work at Oracle and other Redwood Shores businesses.
PX - Used to be 18F. SamTrans consultants recommended to cut the route 10 years ago citing Caltrain competition. Caltrain does provide faster and cheaper service... except that you have to pay more to transfer to Muni to get to downtown. Direct bus service will still be available on the KX, but the bus has to loop by SFO terminals and will run hourly on December 20.
RX - Used to be 17F. SamTrans consultants recommended to cut the route 10 years ago. The bus had three round trips in 1999. Now it only has one round trip. Direct bus service will still be available on the KX, but will be slower and less frequent.
The express buses were essential at a time when BART was terminating in Daly City and Caltrain (which at the time was funded by the state) was providing less frequent service. Express service begin to decline in the 90s after SamTrans committed to extend BART to SFO and to financially support Caltrain. Despite the completion of BART to SFO, SamTrans maintained express bus service over the years because of advocacy from long time bus riders, which contrary to popular beliefs, know that rail is not necessarily superior.
Unfortunately, unlike VTA, SamTrans does not have full information about its productivity and ridership on its buses. Financial pressures at SamTrans and Caltrain, as well as political pressures from folks at the pro-rail MTC, forced SamTrans to make mostly a political decision to give up the commuter market. While service could be restored on other routes currently slated for service reduction once economic condition improves, it is really the end of the line for these express bus routes. Why would SamTrans restore commuter buses again after it had kicked all of its remaining bus riders onto slower buses, BART, Caltrain, and even their cars? MTC would see this as taking riders and revenue away from BART and Caltrain, which is a political no-no.
FYI: VTA lately is allowing commercial ads on its light rail exterior.