I see this at work quite often. It seems to be a common strategy with most Corvids along the railway. They are looking for "rail kills" which are common, especially on the higher speed routes.
Unfortunatley, they also attract Buzzards and other birds whilst feeding. The Corvids have a knack of getting out of the way at the last minute, and the poor Buzzards tend not to be as aware/agile and end up as Corvid food.
The same behaviour can also be seen out on the country roads.
Woodpigeons must be one of the less intelligent birds. They often roost on the rails, especially in wet weather, and as the train approaches, they just put their head under their wing....................
I was at Prestwich Metrolink Station yesterday (Sat) morning. I saw two jackdaws walking along the tram lines, the actual rails. They walked along the rails for quite a long way, looking down at either side. I imagine this is a regular thing, and that they were looking for food. Anyone else seen this? They were walking in the direction of Manchester, incidentally!