Nowadays people write business letters in a more jounalistic style than a formal one. That is, they are concerned with an important "lead" that will get the attention of the reader. Placing the strongest argument in the first paragraph is essential. Having facts and figures, such as those that demonstrate the economic and physical advantages of having an additional bus stop will be convincing. For example, you could include as an attachment a graph that displays the statistics which you have gleaned. And, do not forget to express your appreciation for his attention to the matter.
Essentially, your letter is a concise persuasive argument with concrete support attached. If you know the traffic controller's name, it is proper to address him as Dear Mr. ___: in your salutation. It is acceptable, also, nowadays in the U.S. to use Sincerely yours, rather than Yours truly which has hitherto been deemed de rigeur.
See the site below on how to write a persuasive argument
In order for you to write a good letter, what you need to do is to figure out what your best arguments are for setting up this bus stop. To do that, you need to think about what the benefits of having a bus stop are -- both to people in your neighborhood and to the city as a whole.
In terms of benefits to your neighborhood, I would talk about the number of people who would use the bus and where they are likely to go. If the bus route would head to the downtown area of your city, I would talk about people being able to take it to go to work or to go out for entertainment (like to movies and such).
In terms of the city, I would emphasize the reduction of traffic that could go along with this new bus stop. I would talk about how many car trips could be prevented by having better access to public transit. This would be especially important to a traffic controller.
Your letter should be typed on a computer and printed on A4 Bond Paper. Observe all the rules of an official letter.
You should begin by giving your name and address on the top left hand corner. On the right extreme corner you must mention the date on which you are writing your letter. The date should be written in the following format: day month, year.
Next, comes the salutation. You should begin with 'Sir'
Next, leave five spaces and type Sub: request for bus stop at ..... name of your locality.
Next comes the body of your letter. Start typing flush from the left margin. Clearly state the reasons why you want a bus stop in your locality - number of people to benefit, school and college going children, office goers.
Conclude with 'Yours Truly' typed flush at the left margin.