May 7, 2013
This sign at 13th and Pennsylvania sums it all up. On the top, instructions for bicyclists to obey the traffic light; on the bottom, a sign explicitly banning U-turns.
I ride this stretch nearly every day, and almost always see drivers (especially taxi drivers) making U-turns. I also see bicyclists going through red lights. I've never witnessed enforcement for either violation.
The problem with illegal U-turns is that they're dangerous. Drivers have to cut through two bicycle lanes and find an opening in traffic on the other side. The situation got so dire last year that the mayor announced emergency rulemaking explicitly banning U-turns. But he didn't mandate any enforcement, so U-turns regularly occur to this day.
Red-light running is its own problem. I never do it, but plenty of people do. I understand the argument for allowing Idaho stops, but when the signage explicitly says "obey this signal" it would seem that Idaho stops are not justified. The real problem is that red-light running is fuel for the anti-bike crowd's fire. Like it or not, drivers use it to justify their own law-breaking and you can witness this attitude in any debate where a legitimate complaint is lodged against a dangerous driver.