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Comment by mojomark | Hacker News Reader

At 5AM, as I sit waiting for a traffic light on a deserted stretch of road during my morning commute, glaring tempestuously at the nearby redlight camera, I wonder how we've gotten to driverless cars before getting to 'smart' intersection signaling systems that know there is a lone commuter patiently waiting to pass.

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It has to do a lot with reliability and cost. A smart car has a lot of expensive sensors and an expected life of a few years with regular maintenance. There's also a huge market opportunity around smart cars. Those cabinets can last decades, in all conditions, with minimal upkeep. Adding sensors decreases reliability and increases maintenance cost. There isn't usually an appetite to put traffic signal upgrades or extra maintenance headcount in city budgets for non-critical infrastructure upgrades, so the financial incentives to innovate are more limited as well.

Thanks - interesting. I know traffic pattern/flow models and studies can be extremely complex. However, from the perspective of a 'dumb' commuter, it seems like the investment in smarter traffic signals would be offset by global savings from/economic benefits of reduced congestion (e.g. idle bus transit fuel/maintenance savings or generally increased standard of living and economic imprivements due to increased traffic flow).

It is useful to talk about both inefficiency (the thing you point out) and exploitability (the ability for any individual actor to make useful amounts of money out of fixing the inefficiency.)

Unless an area is both inefficient and exploitable, it is plausible that it will go unfixed for a long time.

When you start viewing it in those terms, you find obvious inefficiencies everywhere.

If you were on a motorcycle instead of in your car, you could watch as those "smart" systems go through a few cycles for the vehicles travelling in the other directions without ever once giving you the green light.

Fortunately, the state I live in (Indiana) finally passed a "dead red" law a couple years ago, meaning that I can now disregard that red light and proceed through the intersection anyways (assuming it's all clear and safe to do so).

You also have the option of attaching a magnet to the bottom of your motorcycle sufficiently strong enough to trigger the induction loop.

https://en.wikipedia.org/wiki/Induction_loop#Vehicle_detecti...

Sensors are common, ranging from basic induction loops in the road to microphone arrays that can tell you what type of vehicle is on each page of an intersection from the tire noise.

Sadly there are laws that require each light to be green for a minimum period, so all these really do is keep one phase of lights on longer at rush hour.

I wonder if the transition from human-driven vehicles to self-driving will bring a resurgence of traffic circles in the US as an intersection that can readily support any mixture of self-driven and human-driven.

Traffic circles where I live are a complete boondoggle. They are seen by city planners as a wonderful, progressive, very forward-thinking concept. And I have no problem with them in theory. But when they convert a normal "four-way" intersection to to a traffic circle it always seems to take about a year, is built far larger than necessary, requires annexation of pieces of private property around the perimeter, and features a large center island with trees and ornate landscaping.

I can't see a reason it should take more than a few weeks to round out an intersection and remove the stoplights/stop signs.

There are reasons to make roundabouts with large radii. Ironically, some of them involve traffic-light controlled roundabouts, where traffic queued at a red light queues back around the roundabout. The consideration here is that one makes the circumference of the roundabout greater in order to provide more queueing room before the queue for one junction backs up beyond the preceding one.

The government just upgraded a traffic-light-controlled roundabout where I live, and enlarging the circumference in order to provide more queueing space was one of the considerations mentioned in the public consultation doco.

Also bear in mind how large, possibly articulated, vehicles have to navigate roundabouts versus how they can navigate box junctions, especially since the approaches to roundabouts by design slew approaching traffic to one side. (This is a consideration that for smaller vehicles brought about the idea of the mini-roundabout, and is also behind having overrun areas around reduced central islands.)

It's all a conspiracy to make you not want to drive your own car.

Anecdotally, in my area there are no red light cameras so most people in that situation just stop, look, and go.

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