Question of the day: You can get around the city pretty fast these days from the north side, so how about a turnpike on the south side?
How about: Because it's not needed.
Take a good look at the major thoroughfares around the Oklahoma City metro and you'll see, Mike, that the needs are pretty well handled.
Interstates 35, 44, 40, 235 and 240, as well as the Kilpatrick Turnpike on the north and west carry heavy loads of traffic each day.
In addition, you have some state highways, such as 3, 37 and 9 that offer alternative routes.
Sure, there are construction or repair/rehabilitation projects here and there on these roads, but those are necessary. Again: heavy loads of traffic each day.
The major road on the south edge of the city is I-40, running east and west through the metro and beyond. A little farther south is I-240, carrying traffic that can exit onto I-44 on the west and I-35 on the east.
You have I-44 on the northern edge, giving motorists a connection with I-35 on the east and I-40 on the west. I-44 becomes the Turner Turnpike on up the road. I-44 also makes that connection on the west with I-40.