KR's problems started with the accidents caused due to landslides on the route, most notably that of the Matsyagandha express. Subsequently they faced considerable pressure from the CRS and the Board to curb speeds on the route and improve safety standards.
The builders of KR showed remarkable foresight by planning a high speed route from the outset, using straight alignments and avoiding sharp curves as much as possible. A testament to this fact is that unlike the other high-speed sections of IR where speed trials are done on short sections, the entire section from Madgaon to Roha, a distance of about 440km was tested at high speeds.
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may not be cleared for high speeds by today's standards. But that is a sad reminder of wasted, unappreciated efforts. A route that was once cleared for high speed operations, and was poised to start running services accordingly, remained stagnant after some initial setbacks. That nothing was done in the intervening 15 years to solve the problem, does not help.