There’s a concept in road design that says the engineer must first determine the design speed, which is basically how fast they want traffic to be able to flow. This part of the process is generally not part of any public hearing or put to a vote by public officials - it is just decided on and then they move on to the next step.

There’s also a prevailing concept in road design that seems to indicate that high traffic speeds are a design issue, but low speeds are an enforcement issue. The road is designed to accommodate the highest amount of traffic anticipated in the future without really thinking about if that’s even a good fit for the area.

Once the road has been built to exacting standards (which means it is far too wide and flat,) the city steps in and slaps a speed limit on it, often at odds with the design speed.

When residents get worried about all the speeding cars, they petition the city for a traffic study to see if anything can be done. The engineers conducting the traffic study determine that the road is capable of handling higher speeds than the current limit, and so to cut down on speeding the recommendation is to increase the posted limit.

It’s amazing to me how much influence the engineering team has on the design with basically no accountability. You can try to reduce speeding by putting up speed traps and police patrols, but at the end of the day people will drive as fast as they are comfortable with and that is often a result of the design of the road they are driving on.