Why are residential roads higher in the middle than at the curb?

Why are residential roads higher in the middle than at the curb
In at least 250 words, give a full and complete answer to the question. I would like you to find out about the material and describe the answer in your own words. Most of these topics require some research. Don’t forget that you must give attribution to your source. Be sure to cut and paste the URL of the site from which you got the information. Sometimes other students decide that a topic is interesting and would like to learn more about it. Your source will provide them with a good starting point. This initial post is worth 6 points

Why are residential roads higher in the middle than at the curb