No Right Turn On Red signs can sometimes produce unintended results.
After our marriage, me and the missus rented our first house in St Paul on a fairly busy main road. After about 6 months, we noticed that all of a sudden, we had cars zipping down our alley. (All blocks have old fashioned alleys between the streets where the garages were located.) Couldn't figure it out for a week or so. Then, we noticed that they'd put up a NRTOR sign at the intersestion down the street from us. I grabbed a chair and a beer one day, and watched the street. Whenever the light turned red, some drivers would hang a quick right, then go running down our alley and make their right at the next street, thus avoiding the NRTOR sign. This became a huge safety issue, as there were many small children on this block. (Including, eventually, our own.) We campaigned to get that sign taken down, but the city wouldn't budge, citing a couple of serious accidents at that intersection. I invited a city policeman who happened to be parked out front doing paperwork one day to watch. After noticing a couple of cars do it, he went back to his car for his radar gun. He timed one young gal in a Jeep CJ5 at 33 mph. You should have seen the look on her face when she spotted him. She actually locked the brakes up slowing down. She got a nice hefty speeding ticket for her trouble. The cop said he'd try and do something about it, but nothing ever happened. We eventually bought our first house in another neighborhood, and forgot about it. One day, I stopped by to visit an old neighbor, and learned that a young boy had indeed been hit by a car short-cutting down the alley. Luckily, he recovered. The family didn't just sue the driver, they sued the city, citing this as a long term problem. The ex-neighbor said that after the suit was filed, the sign came down.
A couple of years later, I read in the paper that the city had gotten into the habit of putting them up whenever neighbors near the intersection asked, and were soon all over the place. They actually took about 90% of them back down. After that, it got a lot tougher to have one put up. This was back in the mid to late eighties.
I don't know if it's true elsewhere, but in Minnesota, if you're at an intersection of two one-way streets, you can turn left on red as well if the directions permit.