an article from Wikipedia which can be of some help to you
Also, the Duronto trains
were known to be much cheaper than
the Rajdhanis while they run faster and
are more efficient...
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than the Rajdhanis.
They also had AC three tier-Economy
coaches which are Air conditioned
coaches with sleeping berths, now
present only in Garib Rath Trains.
Berths are usually arranged as in 3AC
but with three tiers across the width
and three longways. They were slightly
less well-appointed, usually no reading
lights or curtained off gangways.
Bedding is usually excluded from fare
and was available with a payment of
25 (US$ 0.46) per passenger.
However, these coaches were soon
suspended and the Duronto trains had
no Economy coaches after that. In
March 2011, the cost of travel in the
Duronto Express too went up as Dinesh
Trivedi from the Trinamool Congress
became the first Minister of Railways to
announces a hike in railway fare. The
decision to hike railway fares resulted
in trouble across the Government and
were rolled back, [7] only to be raised
again on April 1. [

1. one mainly because of patronage and status that rajdhanis have
2. Rajdhanis stops at intermediate stations and as a result a part of some seats remain vacant e.g. i traveled 12301 i 1A from DHN and the other person in the coupe was to board from GAYA, now from HWH to DHN , and from HWH to GAYA in H1, G, the seat remained vacant which in turn is a loss, as this is not the case with Duronto (End to End fare)
3. Railways do not employ TTE for the entire...
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journey in Durontos once checked at the originating station the TTE leaves the train at the first Technical stop and the rest security is handled by the GRP and RPF, which is not the case with Raj
4. It has been seen that the food quality is not at par with the quality of food in Raj