Thanks to everyone who has replied so far!

I will look over all sources suggested, and explain further what I mean.

When trying to find an average speed between two stations, I will be incorporating stops. So for example if the train travelled a distance (along the tracks) of 10km, and stopped twice, so that the overall journey including stop times was 10 minutes, I would find the average speed using speed=distance/time from these two figures.

I hadn't thought about trains taking different routes from the same initial point to the same destination, I would probably work out the speed for both journeys and calculate a mean.

Overall, what I was hoping to find was an average speed for all journeys less than five miles along the tracks.

Essentially, I am trying to calculate the carbon emissions of various forms of transport to school. From the department for transports figures I know most children only travel on average 3.2 miles to school, which is why I am only trying to find average speeds for journeys of less than five miles (

https://assets.publishing.service.g...ment_data/file/822089/nts-2018-factsheets.pdf). I have also found the average carbon conversion factor for train journeys in gCO2eq/km (equivalent grams of carbon dioxide emitted per kilometre), from DEFRAS 2019 carbon conversion factor spreadsheet. Since I am finding this value to include in a worksheet for children, I want to make the question as easy as possible for them to answer. So when I am asking them about their journey to school, I am not asking them the distance they travelled, as I feel most children, in particular younger children, will not know. Instead I am going to ask them how long they spent on the train (/bus/car/ walking). Hence the need for calculating an average speed for the trains!

I know the answer will be very approximate, and that it will have substantial uncertainty associated with it. But that isn't too big a problem provided when I write it up as part of my project I discuss this uncertainty

My constraint is currently UK.

I hope this helps, I really appreciate all the help so far!

!!!!