What concepts and business models can enhance the utility of mass transportation systems in urban areas and lead to much higher utilization?

Mass transportation is an effective avenue to make transportation more sustainable. At the same time, a good percentage of urban population worldwide does not use the system for a variety of reasons – lack of convenience and comfort being the main two. What are the avenues, processes and solutions through which we can make a much larger percentage of people use mass transport, especially for urban transport?