Dehradun Shatabdi once was one of the most successful shatabdi of IR ! too many halts , unnecessary loco reversal at SRE and low average speed has ruined it... ideally DDN-DEL distance should be covered in 3-4 hours. but it takes 6 hours. Railways are now constructing a new expressway to Dehradun , the car and bus travel time may further reduce to 3 hours in the coming years... UK government has proposed railway to construct new rail line between SRE and DDN , running along expressway.. but railways has not commented it on yet !