There is something beautifully, almost poetically, simple about Edinburgh's road network. If only more big cities could be this straightforward. There are roads going in and out, you see, and a big tangle of streets in the middle. And to avoid it all, if you want nothing to do with Edinburgh itself, is a fast dual carriageway along the urban fringe called the A720 Edinburgh City Bypass. Simplicity itself.
Of course, life is seldom quite so free of complications, at least where the UK's road system is concerned. The A720 was built relatively quickly in a series of stages in the 1980s, and the fact that it was planned and designed more or less as a single entity ought to mean that it works well.
Sadly, that's not the case. There are actually quite a few little puzzles on the A720, like why there are two west-facing junctions serving Gilmerton and Bonnyrigg, but no east-facing equivalents at all, or why you can get to Wester Hailes from the east very easily but not from the west. Or indeed the biggest conundrum, which is why a road clearly designed to link all of Edinburgh's radial routes, from the A1 in the east to the M8 and A8 in the west, stops at that point and doesn't continue the relatively short distance to the A90.
There is also the headache that is Sheriffhall Roundabout. The A720 should, in theory, be free-flowing from end to end, but it's not, because where it crosses the A7 a flat roundabout (now festooned with traffic lights) was installed and remains there to this day, causing an unwanted break in the journey when traffic is light and lengthy hold-ups when it's not. (Sheriffhall is explored in considerable detail in Bad Junctions.)
Despite all of that, we should be counting our blessings, because at least it exists and at least it mostly does its job, and it's still far better than the ring roads and bypasses provided for many other cities of Edinburgh's size. Though if you're sitting in a mile-long traffic jam at Sheriffhall, it might not always seem that way.