As a driver it helps to know in advance where the areas of congestion are, the amount of parking spaces in metropolitan car lots as well as knowing areas where speed limits have been reduced. Traffic optimization is the science, or at least skill, of reducing the time spent at traffic lights.
How cities prioritize funds:
Sometimes cars have to cope with roads which haven’t been repaired for some time and are full of potholes. It is a challenge to cope on these roads at the best of times, hence why road surface is dealt with first before items such as congestion.
If there is too much traffic in one place (not just clogged up vehicles but also too many cars at a certain time of day) will increase exhaust emissions in that area. You can decrease this by having other ways for the public to reach an area, creating different hubs in a town (essentially removing the high street as the go-to zone, which may not be possible either in a huge metropolis) or having rush hours at different times.
The lights need to be synchronised and need to allow for emergency vehicles to pass through easily.
The contrasting term for all this is “traffic calming” which stops speeding and encourages more responsible driving. As well as reducing air pollution and the increased traffic noise is addressed.
Noisy, polluted streets are not the best to live on; according to Donald Appleyard’s Liveable Streets study a resident on a non-polluted, non-noisy street would have three times as many friends/acquaintances on average compared to those who do not. The study compared three streets in San Francisco, each with a different total of cars per day.
Reducing “cognitive load”
Cognitive load is just fancy was to say making driving more difficult – it pushes traffic off crowded direct routes onto otherwise long ways around. Sometimes the goal is to make it easier to avoid a town entirely.
There’re speed bumps, speed tables (basically a longer hump) and speed dip. As with natural dips the sudden drop means traffic slows up as it approaches the obstacle. There’s also chicanes which is a curve in a road.
Other techniques are narrowing roads and removing lanes-”road diets”. Converting one-way streets to two ways requires more careful driving. Unfortunately, this process does produce more accidents in the first couple of weeks or so.
So basically, government prioritizes road maintenance (fixes potholes) so traffic can flow without building up exhaust, then puts speed bumps (reverse potholes) on the roads to encourage alternate routes.
How does changing the operating hours change the traffic?
A study published in March 2020 used a fairly medium-ish city in China (Ningbo) which has a similar grid shape to Manhattan.
The study worked off an extremely urban area of the city with financial buildings and high-class restaurants. Working off mathematical principles each section of business traffic was measured – 40% of it being from retail and shops. In altering the time traffic moved through the city there was a definite reduction of traffic. As it was only published last year there hasn’t been enough time to establish how practical removing the 9 to 5 is. Only that it creates better streets to dwell on, which at least makes it more desirable for locals.