In most cities and towns, the high volume of road traffic has become a serious problem.

With the rapid increase of urbanization, the traffic noises have has become a pressing issue (We normally say "pressing issue," but if you want to use the word 'problem', then you can just say "..has become a problem for..") problem which bothers for city dwellers. This essay lists some probable causes and feasible solutions. 

There are two likely obvious factors are responsible for this phenomenon (Remember, you said you would be discussing "probable causes" in your first paragraph. Therefore, your wording in this sentence should allow room for some doubt and/or argument since it's all speculation.). The root cause is (most likely a) lack of prevention (I think 'preventive' sounds better than 'prevention' in this sentence, but it still works the way you've written it.) measures. Highways, besides some border trees, are generally expose to the residences along the road (Because your essay is about traffic/road conditions causing problems for city dwellers, shouldn't your sentence be flipped? You should say something like: "Aside from some minor protection from bordering trees, residences along roads are generally exposed to (noisy) highways."). Another trigger ('Trigger' seems like an odd word choice to me, but you can keep it. It's partly style.) is the emergence emerging of a greater number of cars. To be precise, under the pressure of high rent in the city centre, individuals now are preferring to live in the suburbs. It is more convenient to own a private car (Saying "private car" is unnecessary here, just "car" will do.), which leads to a growth number of transportation (I don't understand what you're trying to say here. It leads to a growing number of vehicles on the streets?). 

Thus, various approaches could be considered in order to solve are considerable in solving the problem. Setting up acoustic barriers, manifestly, is the most plain way to deal with it. With these protection of barriers, 60% of traffic volume can be turned down. Moreover, the authorities should improve the public transportation system. The development of public transportation will lead to a reduction in (the number of) the reducing of plenty of running vehicles. 

According to the this viewpoint, the discomfort (I don't think 'discomfort' is the best word choice here. Perhaps 'inconveniences' would be better.) of high volume of road traffic can be avoided by several (relavant [correct spelling is 'relevant]) methods. We are looking forward to seeing the a (more) tranquil future.