180 kmph is an operational on a line right, multiple routes are operational above 140? Those above 140 are called semi high speed trains.
And they will be all over India soon before bullet train starts.
Very few lines are certified to run 160 KMPH. Most of the Indian Railways runs at the average speed of 60 Kmph hours. We have some 130 MPS tracks in some sections, but it will take a decade to upgrade entire infra.
Currently from Chennai to New Delhi
1. Rajdhani takes around 28.5 hrs with 77 Kmph as average speed.
2. Tamilnadu SF takes around 33.5 hrs with 67 kmph as average speed.
Increasing speed in India needs to be done in multiple fronts.
1. Removing non-AC rakes completely. We got some glimpse in the form of 3E which will replace all S Class.
2. Modern Signaling systems. Only TCAS in the form of Kavach is coming, hope signaling will start soon.
3. Track infra improvements like continuous welded tracks for high speed, changing alignment of tracks for higher speed. Work is going on, but it takes a decade to finish.
On the other hand both Pakistan and Bangladesh railways are piss poor with nothing to show improvement.
Pakistan railway is basically a dead weight with rampant corruption, no freight operations (moved to road).
Bangladesh relies on India and China for Cheap locomotives and coaches.