Train strike May 15/16

No, you can't (in a good way) count on the strike happening. A lot of times the industrial
action/strike is cancelled or postponed. It all depends on the negotiations and mood of
the union vs the management/government. Sometimes it gets to the 11th hour and things
get called off.

If it does happen, there is also no guarantee the strike will be nationwide. But I do believe
(and others may know more) that during the window of time you mention, that the strike
action cannot take place and trains will run per the posted schedule. However, if your
itinerary includes a train that departs after the strike interval starts, who knows.

For better or worse, you just need to monitor the situation, and have backup plans up your
sleeve. Not 100% sure about Italy, but usually, your ticket is good for any train that gets you
where you want to go in the event of a strike.

I don't think anyone can 100% if the strikes will happen or not.

The bad news is that small, local rail is most likely to be affected. The guaranteed trains tend to be large trains that run from big city to big city and it is usually 3 in the morning and 3 at night.

As a back up I would look into other forms of transportation.
I believe there is a La Spezia to Lucca bus once or twice a day. I'm sorry I have no idea if the train strike will stall out traffic on the local CT line and prevent you from getting to La Spezia except maybe by ferry.
You also might look at a tour company or dedicated NCC driver to get you from CT to Lucca.
I have used this company: https://en.turislucca.com/ for local guides in Lucca and they also do cruise ship transportation tours. Maybe they will come pick you up in CT and then get you to Lucca along with a tour of some kind.

There are Lucca to Florence buses and then you could take the bus to Siena. As I recall there may be a once a day bus from Lucca to Siena but it was a horrible time like 7:45am. It is the most direct way but your time in Lucca will already be short and then you'll leave super early. But during a strike you may want to trade tourist time for definitely getting there.

Keep in mind that while the strike is on others will be looking to use buses and even when the strike ends and the schedule returns to normal there will be pent up demand - like you - looking to take use it.

Hopefully the train strike will not happen at all, good luck,
=Tod

I found tourist information offices in Italy very helpful when I was trying to figure out and navigate strikes. When you get to Vernazza consult with the TI there for updates and alternatives. Once you are in Lucca, check with TI there.
It looks like most trains from Vernazza to Lucca require two transfers; one in La Spezia and one in Pisa. So, you need to check Liguira trains for the first leg and Tuscany trains for the second leg. However, if a strike has started when you get to Pisa, taking a bus from Pisa to Lucca should be an option unless bus transport is also on strike.
Other options: Consider renting a car for 2 days. Or, consider trying to change your plans so that you travel on the 14th or 17th. I found hotels understanding when contacted in advance to add a night to one and drop a night at another due to anticipated strikes; however I was within the cancellation timeframe.