We are planning to travel to Herculaneum from Naples by train. Rick Steves' book notes that there are trains every 20 minutes from Naples. When I go to the EAV website, I see the Campania express trains stopping in Ercolano about 4x/day and the Circumvesiuvian only 4 x/day more. However, I have seen a different train that travels from Naples to Poggiomarino that does seem to be every 20 minutes. Are these the Circumvesuvian trains or something different?
The Circumvesuviana line that runs from Naples to Sorrento (there are other lines) runs on about 20-30 minute headways, with no reservations and no seat assignments. You're lucky if you get a seat and if the train is on time! This is a hot, gritty, commuter train, but it's very cheap, and does the job well enough.
Note that it's a 12-15 minute downhill walk to Ercolano Scavi, the ancient city excavation. Unlike Pompeii, there is no food inside Herculaneum, and you cannot exit and re-enter. There's also the issue of "slow food."
https://www.visitpompeiivesuvius.com/en/naples-to-sorrento-train-schedule
Circumvesuviana schedule
It appears that not all trains stop at Ercolano
https://www.positano.com/en/naples-to-sorrento-train-schedule?timetable_route=sorrento_napoli
As far as I know that is the only train along that route
Trenitalia trains go from Napoli Centrale to Portici-Ercolano. You can walk from there to Herculaneum. This train line runs more frequently than the Circumvesuviana. It is about a 1 mile walk from Portici-Ercolano to the Archaeological Park.
Thanks for the responses!