1) Mumbai is already suffering from massive space constraints and traffic issues. A trip in a car is usually slower than walking that distance (assuming the infrastructure exists and you can walk without falling into an open pothole).
Mumbai desperately needs more public transport, and needs to add safe biking, also because of #2
2) Mumbai has very few roads per person, and further, it doesn’t have space to build anymore. Besides the fact that this means cars are not sustainable at all in the city, it also means there’s not too much quiet asphalt that would be needed to replace the existing road material.
3) Mumbai already has an excellent public transport infrastructure, especially with buses. That system is currently unworkable because of all the cars clogging the road. If you were to have dedicated bus lanes, and increase service drastically, it would solve most of Mumbai’s transit issues.
4) Cars in Mumbai rarely travel over 30km/h anyways. Just moving usa. Welcome miracle for the most part.
1) Thanks to the north-south alignment of the city (further aggravated by the commercial-residential area distribution along the north-south direction) there is just an extremely high population load involved in mass movement twice a day (of course, in the usual circumstances). Better infrastructure wouldn't help so much as more structural changes like redistribution of these areas or enforcing staggered working hours.
2) I feel this is more of an administrative problem - the current model of tenders does not work very well and there seems to be little or no incentive (or deterrents) for contractors to keep roads in good shape. The current road infrastructure is dismal and would require a major system overhaul to facilitate finances and will required for replacing the existing material with quiet asphalt. But yes, this probably seems more doable.
3) The municipal corp did consider having a BRTS system (a la the Bogota model) but their surveys led to the conclusion that improving the existing suburban rail system with more frequent services was more impactful. In terms of point-to-point connectivity, Mumbai certainly has very good infrastructure (especially compared to Bengaluru and Pune).
4) Don't forget about the honking! There's little or no honking in Delft.
Naturally, Delft cannot be compared to Mumbai (whose population is more than the entire population of the Netherlands), but having had first-hand experience of spending a considerable amount of time in both places, I simply cannot overstate the peace of mind felt with extremely low noise levels. As far as a good solution to noise levels in cities like Mumbai goes, there's a whole lot to be done - and a Delftian approach certainly wouldn't work.