Any urban change takes decades, especially if you have to build things. For example it takes years from proposal to completion of a single bike lane. Digging subway tunnels is much slower. Here in Berlin we're still debating plans that were originally drafted in the seventies.

I think the most effective tool cities have is zoning regulations. Getting them right enables the city to harvest organic change as opposed to having to plan every single project. Reducing free parking and allowing mixed commercial and residential use seems to me like the easiest way towards a public transit centric city. In Tokyo for example there is basically no curbside parking and shops are always within walking distance.