Regarding bus public transportation and dedicated lanes or ramps. To build a bus metro system you need the appropriate space for it. If you integrate it into your existing road network, said network should be able to already cope with the road traffic on its own. This almost never happens (the ironic part is that if it did, you probably wouldn't really need a bus transportation system anyway), meaning that you have to either reduce road traffic so that the dedicated lanes that remove throughput from it can work, or simply decouple the bus system from road traffic - via building elevated ramps, for example, or dedicated lanes with no (easy) access to the road network.
This is a catch 22 for many cities. The best option is to simply bite the bullet and move to a subway train system, using buses for connecting parts of the city to the subway network itself. This is costly though, and very time consuming too.
If you HAVE to do a bus network, elevated ramps or decoupled lanes is the next best thing. It is costly, but pretty much ensures that the network will work with good efficiency/punctuality, and - in the case of elevation - that the existing road network will not be affected majorly. In this case - but by paying more - you can also replace buses with trams, since they are better for the environment and also even more efficient.
Co-hosted bus and traffic lanes is the cheapest solution, but also the most inefficient in throughput. The lanes get hobbled with illegal road traffic, the large buses entering the system make the existing traffic problem worse, the people using the buses cannot really depend on them on getting to their destination punctually, and you need strict law enforcement to even make the thing work. Many cities have to rely in such a system because there is no other choice really. It is not a good choice though.
Lastly, there is really no such thing as "profitable" mass transportation. These systems are a priori designed with other goals in mind (serving the community, boosting property, tourism and business values, reducing pollution and traffic congestion, providing access to transportation for sensitive social groups like the poor or people with disabilities, etc etc). You cannot reliably set a ticket price that would get back your investment promptly, simply because this runs contrary to the MO of the system itself. This is why transportation infrastructure programs like these are often funded or co-funded by governments, with private initiative moving to the contractor side of the equation.