It is not possible to increase speed without converting these stupid Narrow Gauge tracks to BG. When these people will get a brain. Putting these under some dumb Unesco Heritage is just keeping these places off to better connectivity.
Have some commonsense and convert these tracks to BG or make some alternate tracks to Shimla or Joginder Nagar.
P.S. I do want to see a direct rail connectivity to these places in my lifetime.