Not entirely sure it is a good idea to renationalise the railways, also has he pledged to renationalise the ROSCOs?
Put simply, it would be limiting the investment to the public sector funds, which is never a good thing as when spending is tight the government tends to cheap out on such things at the expense of service and a longer term vision.
Also BR wasn't the passenger friendly organisation people think it was, it seemed to have an attitude that it was providing you with a service and you had to be thankful, which isn't always a bad thing - but certainly isn't always a good thing either.
As a Labour member myself, I have to say I'd rather see more joined up thinking first and better privatisation before I'd rather see renationalisation. I shall be putting Mr. Burnham third preference , ahead of Mr. Corbyn.