A daytrip to Pompei Scavi from Rome is a popular undertaking for many travellers, who typically choose between taking an organized bus tour or going "on their own".
Many travellers understandably prefer to avoid organized tours, which invariably place significant limits on one's flexibility, as well as actual time at destination. However, some have noted the steep fares of the fast trains between Rome and Naples (currently 88 Euros round-trip in second class on the fastest AV train).
Fortunately, it is possible to do this daytrip by using the trains and spending well under 50 Euros per person: taking the Intercity (IC) train in both directions, rather than the more expensive AV and ES trains.
The difference in fare is very significant: 41 Euros round-trip on the IC versus 88 Euros on the AV or 68 Euros on the ES (all fares are second class). The difference in travel time compared to the ES train is modest: only 18 minutes longer each way on the IC train. The time difference compared to the AV train is more pronounced: 53 minutes longer each way on the IC train (due to the fact that the AV train takes the new high-speed rail line). AV and ES trains go non-stop between Rome and Naples. The IC trains usually make three very short stops en-route (Latina, Formia and Aversa).
Seats on the IC, ES and AV trains are all reserved. Given the frequency of trains on this route, don't be too concerned about advance seat reservations, particularly on the early morning southbound trains. Most times (but not 100% of the time), you'll find seat availability up to the time of departure of the train. But the lines to buy tickets at Roma Termini are long in the early morning, so it's a good idea to buy the ticket the day beforehand.
First class seats are also not necessary on this route. These trains are all non-smoking and have air conditioning (which does not work 100% of the time). Many travellers have noted that the IC trains are not as "nice" as the ES and AV trains, although others have not noted huge differences in quality.
In addition to the Trenitalia fare, travellers must also pay 4.80 Euros round-trip for the 35-minute Circumvesuviana commuter train ride between Napoli Garibaldi (underground to Napoli Centrale) and the Pompei Scavi-Villa dei Misteri station, across the road from the entrance to the archeological site. Seats on the Circumvesuviana all all non-reserved. Allow at least 15-20 minutes to connect between trains (based on actual arrival time at Napoli Centrale). These commuter trains run every half-hour.
There are two IC train departures out of Roma Termini station which are particularly useful, if you don't mind a very early start to the day: at 6:27 a.m. and at 7:27 a.m. Travel time to Napoli Centrale is approximately two hours.
The archeological site opens at 8:30 a.m.
On the return trip, there are IC trains from Napoli Centrale back to Roma Termini at 16:30, 17:30, 18:38, 19:30 and 20:30. On the return, travellers should be aware that some northbound IC trains originating in Sicily or Calabria and passing through Naples may be running late (even very late), compared to their scheduled departure times. The afternoon northbound ES trains might also be delayed, as they originate at Reggio di Calabria. By contrast, all the afternoon northbound AV trains originate in Naples, which means that they are unlikely to be running late.
Is it necessary to book the return train in advance? Once again, doing so significantly limits your flexibility, and there's always the danger of missing the connection to Trenitalia from the Circumvesuviana train. (If this happens, the Trenitalia tariff rules gives passengers who have a "base" fare (regular, non-promotional) ticket the possibility of re-booking, free of charge, to a later-departing train departing within one hour of the train which was missed). However, given the hourly frequency of the late afternoon northbound IC trains (as well as the supplementary ES and AV trains), many travellers choose not to book in advance. If you make this choice, make sure you give yourself enough time when you return to Napoli Centrale from Pompei to buy your return ticket (and expect long lines at the ticket windows and even the self-service electronic ticket machines).
You don't need to pay nearly 100 Euros to see Pompei from Rome: it can cost less than half this amount, as this posting bears out. Of course, the primary "trade-off" in using the IC trains is the longer travel time involved: travellers are saving money by spending more time sitting on a train instead of enjoying Pompei. It comes down to a personal decision. Some travellers will opt for the fastest trains (the AV), even at more than twice the cost of the IC.
Fares and schedules quoted above are believed to be accurate as of the date of posting, but are not guaranteed to be correct, since they are taken from internet sources which are not always current. Travel times are accurate but not guaranteed to be exact, and are always subject to travel conditions, delays and other unforeseen circumstances. The IC train departures noted above are not necessarily daily. The Trenitalia website should be consulted by inserting the actual travel date. It's also a good idea to print out the list of Trenitalia afternoon departures from Naples to Rome. Also, fares and schedules are subject to change and should always be verified prior to start of travel. The foregoing is general information, and should not be relied upon in the absence of individualized travel planning.
www.ferroviedellostato.it (Trenitalia)
www.vesuviana.it (Circumvesuviana)



