How to calculate distance from point A to point B taking into account the availability of roads and public transport?

Question

Imagine I have a PostGIS database with following pieces of information

1. OSM (OpenStreetMap) of a city,
2. the roads/streets inside the city and
3. the routes of public transport in that city.

I want

1. to calculate distance from building A to building B in that city via streets/roads (for people with cars) and
2. to estimate the amount of time it takes to get from building A to building B using available public transport (for people without a car).

Is there any ready-made (open source or commercial) software for performing such calculations in PostGIS?

Answer 1

For public transport planning you should check OpenTripPlanner, too. After the link, you will see various examples, not all works, but Athens does.

Answer 2

It seems that PgRouting does exactly that. Here's an intro.