30 miles per hour is the speed of the train.

Logic: use below line as clue

each boy managed to escape the train at the exact instant in which the train would have hit and killed him

let A is running toward the train and B is moving in opposite direction.

So the distance which A has to cover=1-2/3=1/3

the distance which B has to cover=2/3

and speed of A and B is same hence A and B will cover the same distance 1/3,

A just escaped when train is at the entrance of the tunnel hence remaining distance for B is 2/3-1/3=1/3

Now B will cover 1/3 and train will cover 2/3 for the clue line to be true

hence train will run 3 times faster then B