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Date: Thu, 28 Dec 2017 22:28:45 +0000

Where I live, five major roads on the east side of town all converge on a single roundabout (traffic circle), which obviously gets congested especially in rush hours. To help the flow there's a flyover (overpass) linking two of the roads directly; this is a rather spindly structure suitable for cars and small vans only, and it's only one lane wide, so the direction of traffic is switched according to demand -- usually into town in the morning and out of town in the afternoon -- from a control room with
CCTV monitoring of the surrounding roads. The are mechanically-operated signs at each end, showing either a 'no entry' symbol (if closed), or '30'
(speed limit) and car and van symbols (if open) as appropriate.

Of course from time to time drivers miss the signs and go the wrong way resulting in a near miss or head-on collision, usually without major casualties luckily as speeds are low, though recovering wrecked vehicles 20 feet (6m) in the air can be a challenge. This has been happening for decades, however in early 2017 the local newspaper reported an increase in incidents in recent years, suggesting that satellite navigation systems could be to blame, with a quick check on several models showing that some tell drivers to use the flyover without checking that it's actually open in their direction first. A representative from one of the makers was quoted as saying that switched-direction roads are used in several parts of the world and navigation systems can handle these, but only if they operate to a regular schedule, which this one doesn't.

As I see it, there are two issues here: (1) is it possible/feasible for satellite navigation systems to handle changing road conditions, both for fixed locations like this and/or wider-ranging difficulties like wildfires?
And (2) how much detail should navigation systems actually provide for drivers? Telling them to stop at red lights, give way to other vehicles
(having a crash is rarely a good idea), avoid hitting pedestrians, etc. seems a little unnecessary.

[There's a vaguely similar item in RISKS-30.52: Navigation Apps Are Turning
Quiet Neighborhoods Into Traffic Nightmares (Lisa Foderaro)]

In the UK there are occasional proposals for road pricing with the aim of reducing traffic congestion while raising valuable funds for road improvements -- the per-mile rate would vary with higher charges for busier roads at busier times. Somebody pointed out that if this made major highways quieter because heavy traffic used country lanes in the middle of the night, would it count as success or failure..? (Presumably smartphone apps or whatever would be developed to calculate lowest-cost routes and times for specific journeys.)

Similar approach in London, UK: http://www.telegraph.co.uk/news/2017/12/31/block-streets-stop-smart-apps-turning-sleepy-roads-polluted/
Block off streets to stop smart apps turning sleepy roads into
polluted rat runs, say campaigners

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