Can I write
Our journey starts on the railway platform?
Or does it start at the platform?
Can I write
Our journey starts on the railway platform?
Or does it start at the platform?
You can say either.
You stand on the platform and you wait on the platform (though you could also say you wait at the platform). The train arrives at the platform. (In the UK, the announcements refer to "the train now standing at platform 7".)
So your journey starts on the platform but it also starts at the platform. I suppose really your journey doesn't start until you're on the train (because if you're going to count it as starting when you reach the platform, why not when you reach the station, or when you leave home?) - in which case "at" is better, because when you first get on the train, the train is still at the platform (but not on it).
The main confusion here comes with the three prepositions: "IN", "AT", and "ON".
IN - If you are referring to a Proper Noun - which is a location.
I am in England.
I will be Brazil tomorrow evening
AT - If you are referring to a place like a park, railway station, bookshop.
Our journey starts at the Railway Station.
I am at the supermarket.
ON - If you are actually on top of something. Or a specific day, date.
I am on the bed.
I am standing on top of the mountain
The Answer to your question is:
Our journey starts at the railway platform