There is an intersection on my way to work where a street with a 35-MPH limit turns onto a street with a limit of 30 and to make it “easier” for people to negotiate them they have rounded them off more. I can now take these turns and not have to slow down. This is OK in a Miata, but when bigger cars do it they still can’t keep it on the road. They either cut more off the turn and run over the persons lawn or they get their left side tires off the left side of the road. Traffic engineers will analyze this intersection and probably round the turn off more. This will encourage more speed and the cycle will repeat. What they need to do is sharpen up the radius and either put a curb on both sides of the road or better yet, a ditch.
They also need to narrow some of these streets down. The bigger road encourages bigger speeds. There is a section of road that I sometimes travel that goes from 2 lanes to four and the speed limit stays the same 35-MPH. Yet as soon as traffic hits the four lanes the speeds jump about 10 MPH over the 40–45 they were already traveling.
Wider lanes also mean less attention needs to be paid attention to lane discipline. Another bit of road I frequently travel passes through the horse/historical district of town and because of that it still has the same narrow lane width it had in the 40’s. When driving on this stretch people travel slower than they do when the road widens because they have to pay attention to whether they are on their side of the white line.
Then again if I had my way, they would only allow Miatas on the roads and all the lanes would be narrow and windy.