Answer by Balaji Viswanathan:
Modi is from Gujarat and thus it might be legitimately argued that he put his weight on the project [in a democracy, leaders listen to their voters – accept that]. However,project has been in works for a long time from the times of Lalu Prasad & Manmohan Singh – neither of whom are from Gujarat. In various feasibility studies done by the previous government, this route came at the top.
Other corridors considered by the previous government:
(i) Delhi-Chandigarh-Amritsar (450 km approx.)
(ii) Pune-Mumbai-Ahmedabad (650 km approx.)
(iii) Hyderabad-Dornakal-Vijaywada-Chennai (664 km approx.)
(iv) Chennai-Bangalore-Coimbatore-Ernakulam (649 km approx.)
(v) Howrah-Haldia (135 km approx.)
(vi) Delhi -Agra-Lucknow -Varanasi – Patna (991 km approx. )
- Traffic: Mumbai-Ahmedabad is among the busiest lines in the country  and is also a part of the broader Mumbai-Delhi route over which the line might be extended in the future. Any investor would look for routes with the maximum travelers possible.
- Rich travelers: Mumbai-Ahmedabad route involves a number of business executives and entrepreneurs who might not hestitate to pay the heavy ticket price if the trip could be made in 2 hours. Only a couple of other routes [involving Mumbai, Bangalore, Hyderabad and Chennai] have this advantage.
- Flat terrain: The route is flat as a dosa and almost right at the sea level. The train moves completely in the yellow region on the left. This makes the track investment less risky and less expensive [one reason why Pune was left out]. Mumbai-BLR on the other hand involves some elevation climb through the Western ghats [dark green zone].
- Land acquisition: It is possible that part of the line will be new – instead of just over the existing routes. Gujarat has been traditionally successful in land acquisition process and Modi can be sure that he can get anyone on the route cleared. In most other routes, the state governments are too weak to clear out the impediments. Investors don't like too many delays from the NIMBY folks.
In theory, whom you vote for should not determine in what services you get. But, in practice it always does. This is why siding with the right leader at the right time is a prudent move.