Lord Legion: nah, nothing to do with the roundabouts. Local authorities being the useless, stodgy beaurocracies that satire usually paints them as but you never quite expect them to be, that's the problem. Usually totally unprepared for the annual descent into freezing temperatures, even though we have the resources and the weather reports are generally accurate or slightly pessimistic. All the roads and walkways end up being affected equally. Roundabouts are actually less risky, if properly built (unlike yours, by the sound of it), because all the traffic is at least travelling at about the same speed and in roughly the same directon - there's no serious risk of high speed, side- or head-on collisions like at regular intersections (traffic lights do jack if you're unable to stop in the first place)... just fender benders at relatively low speeds.
The example I gave above myself was a little unfair, as it was a "flurry" (...carrying 2 inches of snow, falling in about an hour) that came out of nowhere and caught EVERYONE on the hop. Our roads are narrow and twisting, snow coverage is generally so patchy and temporary that very few people carry snow chains - and no-one has mud & snow tyres - and very few have sufficient experience or presence of mind to deal with the slippery surfaces... so once it gets deep, packed and smooth enough, or there's a suddent storm like that, everything comes to a crashing halt. Literally. Last time that happened, I'd gone out for a half hour shopping trip, it started snowing soon after I set out ... and I had to abandon my car in the parking lot and take a train/footpath home such was the near-instant snarl up when a busy, 2-lane hillside road became impassable by anything except 4x4s. Which were too wide to work their way through the chaos.
The annoying bit is when you've known it's been coming for at least 24 hours, you go out in the morning... and there's been no ploughing or gritting. That's when it extends from a few half-drunk people slipping over on the sidewalk, to the dark comedy scenes of a couple years ago when double-decker buses were skating merrily sideways across busy crossroads. This actually happened in my city. There's probably archive footage somewhere. The whole thing could have been prevented but for better organisation at the local administration and transport agencies level (who are a hopeless bunch at the best of times, their traffic updates are generally an hour out of date... when a crisis comes down, you may as well say everyone for themselves). Quite a controversy at the time in fact - last year wasn't quite so bad (hence being able to ride my bike for *half* the winter, til salt supplies ran low). Perhaps this year we'll have finally learnt our lesson, unless government cuts mean we get a weather-enforced six week holiday across the new year?