Flying into Paris mid morning, wanting to go to Colmar same day. Reluctant to book train travel in case plane is delayed (Coming from Australia) Any suggestions
I understand why you are wary of booking your train in advance though I think the chances of any inbound delay being very long (i.e. more than an hour or so) are fairly small.
Don't use Raileurope for train info...it's just a ticketing agency which does not list all train departures (and charges admin fees). Use the official French railway website in English:
Your options are:
1. Book a ticket for a train leaving no earlier than 2 hours after touchdown and keep your fingers crossed that you have no inbound delays. It is possible to get exchanges or refunds on a few types of ticket but those tickets are more expensive, changing them involves a visit to the station ticket office and usually costs money and refunds are never given in full.
2. Book a ticket for much later on your day of arrival e.g. 4+ hours after touchdown and be prepared to hang around the airport for ages if you land on time. Perhaps that's an opportunity to get a proper meal and have a rest?
3. Don't buy a ticket until you actually arrive at Charles de Gaulle Airport railway station (Gare SNCF).
You will always have to change trains at least once during the journey. There are plenty of trains from CDG to Colmar every day, usually connecting at Strasbourg. I think the chances of them all being entirely full on the day you arrive are miniscule to nil.
4. Stay overnight in Paris and make the journey to Colmar the next day.
If possible I'd choose option 4, simply because it will give you time to rest & get yourselves together before making another long journey onwards.
Hope that helps a bit. :-)
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