Getting from Naples to Venice Sept. 3

some better train options will become available closer to that date?

Nobody knows. Since there are many different railway works this summer, you should wait up to the first week of August.

On the other hand, there is a Ryanair flight that leaves from Naples airport at 8:10 AM

That's what I figured, Marco, but I thought I would ask if anyone had any specific knowledge.

As a last resort, I could fly, but since I already have six (!) internal flights during my 58 days in Europe this summer/fall, I was certainly hoping to avoid another.

get that flight booked!

playing games of guess when the train runs with an internet journey planner always leaves you wondering what the plan in the database actually says. Most train operators now do this because they saw the airlines get away with it - Gen Z doesn't have the skills to read timetables* and smartphones don't have big enough screens to display them anyway. Trenitalia still produce their half-year timetable and skillfully hides it right in the middle of the Italian pages of their website for about 10 of us to download. The current version is 4184 pages, so I'll assume you take my word for this.

Anyway, the season plan for route AV5, the Freccias from the south to the north east, has about 3 or 4 versions of every train each with a variety of dates for when each version will run. And I've sat here, decoded the italian notes and added them up and discovered something relevant. They never had planned to run any of these trains from 29th August to 31st October inclusive. Trains from 1st November to end of the season are there so it's not as though they ran out of time before publishing deadline. Therefore we must assume that for whatever reason, probably a major engineering project, there will be no trains. And I wonder whether they are under any obligations to run replacement buses for trains they never advertised.

• timetable; a table of times, Quadri Orario in italian. The table has locations running along one edge, usually vertical, and the schedule of each train aligned with locations running in columns in time order across the page for the entire dayset.

for those that can't sleep https://www.trenitalia.com/content/dam/trenitalia/allegati/info/orario-digitale/In_Treno_Orario_TuttItalia.pdf

Therefore we must assume that for whatever reason,

We don't need to assume, RFI has published the works calendar per Region. Passengers going from Naples to Venice will be impacted by different works in different months.

And I wonder whether they are under any obligations to run replacement buses for trains they never advertised.

Trenitalia has the obligation to run the trains you can see on their site, many are flagged as "currently not available" if you put September 2 as day of travel. If the works will last less than expected they will add more trains.

Imho Downloading and translating the all "quadro orari" in pdf is a monumental waste of time: first, they drafted it before December 2025. I.e. before "that orange guy" decided he knew geography better than Obama. Second because you can easily see & download on the RFI website only the updated "quadro orari" of the departure station you are interested in.

Thanks to all for the replies. I am making alternate plans. Since my trip is already far too intense with flights, I will make a trek to Florence from 3:31 pm to 10 pm on the 2nd, stay overnight there, and leave at 7:46 the next morning to arrive in Venice at 12:07 pm. Fortunately I've been to Florence before and know a place to stay very near the train station. Considering everything, I prefer this to the flight alternative and the alternative of taking all of a sightseeing day to make this trip. I fizzle out in late afternoon anyway, so this plan disrupts my sightseeing the least.

On September 3rd and 4th a 6 hours closure of the rail lines under the infamous Ponte al Pino in Florence is planned, but details are still to be announced. So maybe there could be space for some long distance trains still to be announced, but do not count on it.