The problem you raise seems to be a single problem "solving the traffic jam". However, actually to answer this question requires effort from many sides (because of this, I believe that almost big cities all over the world, especially in developing countries like China, Barzil, Thailan, Vietnam,..., are struggling with this problem). As Muath Najjar mentioned, to solve this issue we need many efforts and multiple disciplines:
(1) Civil engineering/planning to design new roads, increasing supply for "bandwidth" and balance (not reduce) the demand
(2) Information and management systems such as ITS to provide accurate and real-time information about traffic state to commuters to help them decide good routes, avoid adding more load to the heavy road segments
(3) Solid investments and efforts from government to realize the aforementioned investigations
As your question is too broad, I afraid that it is difficult to have a clear answer/solution. You should make a clearer question to raising your concrete research issues/problems. For example, if you are doing road planning then what solutions on your mind and what difficulties your are facing. If you are working in ITS, then what are they (your solutions/ideas, and concrete difficulties). Doing so, I believe that, many experts in the related fields here can provide you their great suggestions.
Bests,