By the time I got to Houston segregation was blurred and informal. I was frowned on for watching the MLK day parade in lunch hour which included John Glenn, astronaut near the head of the marching bands. Altogether a much more civilised show than say Notting Hill Carnival. There was the Vietnamese quarter near the Medical Center, and the Brit expats tended to congregate around Kirkby Drive. Mexicans were definitely the third class citizens. Yet one true Texan Christian lady in the office in her embroidered blouses saw it as her duty to foster two dissolute Mexican teens who were constantly getting into trouble: I recall the boy having been picked up in Brownsville having stolen a car in search of drug deals at the border.

But there was no naked animosity, and most people were friendly. I never felt at personal risk, even travelling on the bus as I did occasionally.

Relatives tell me that Chicago is now a dangerous city: no more strolling down the Magnificent Mile admiring the architecture.

Washington DC was a city living apartheid when I was there. Extreme segregation of housing, shopping etc. The race riots of '68 left a deep scar.

It dosen't add up.

My first visit to the USA was to Houston in 1958 when transport was still segregated. What a culture shock that was I have never forgoten it.

When I worked in Houston I had an office on the 34th floor that looked over some key Downtown streets. The area is roughly 10 blocks square, with alternating blocks being one way in opposite directions. Traffic lights had two modes of operation. During rush hour traffic could get through several blocks by rolling at 25mph before being paused to let the traffic at 90 degrees to flow similarly. During the day or after rush hour in the evening the lights were more responsive to traffic flows which could slow your journey if it was in a less popular direction.

WE have always known this but it is good to see it spelled out by a real expert.

https://www.netzerowatch.com/content/uploads/2023/06/Eschenbach-Climate-Models.pdf

Everybody's favourite Scandinavian "climate campaigner" is going a bit Dag Hammarskjold?

Recent EU rules (adopted by the UK govt even though we didn't have to) require new vehicles to know when they are speeding. I'm not sure what they'll do if they detect speeding (send an automated summons? shut the engine down? call the cops? take control & drive you to a police station?). Recent hire cars that I've driven displayed the current speed limit on the satnav screen but were not entirely accurate - most obviously, on the motorway an MG SUV thingy kept insisting it was 60 mph when it was 70, and didn't always respond to changes in variable speed limit, which doesn't inspire confidence that auto-speeding detection will be entirely reliable.

Some of these cars had lane departure warning systems, which seemed easily confused when changing lane or leaving/entering a slip road. Autonomous driving cars seem a long way off.

It doesn't add up... (and tomo of course),

it suggests that autonomous systems are sufficient to produce an emergent result that works

Yep. The Internet was built on that principle, and still largely runs on it. However, the vehicles in today's traffic snarl ups are already autonomous, in that sense. Each driver makes his own decisions trying to get a move on. The benefit of an automated "jam handler" driving mode might be in consistency and enforced patience.

On I-70 in Colorado there was a notorious choke-point between two tunnels. Drivers would resort to "rat-runs" through towns, emerging further up the snarl which, of course, was a large part of the problem. They adopted an interesting remedy: police "pace cars". Two police cars travelling abreast at (typically) 45mph (in a 65 limit). According to my friends there, it was a huge improvement.

Another somewhat interesting idea is how Sydney's traffic lights are run. We've never built a decent expressway system, and roundabouts are problematic, so most critical junctions are handled by traffic lights. On the surface, the lights seem idiot simple; they even stop the main road when there's little, if any, cross-traffic. What they're really doing is *compressing* the traffic into packets. A cycle of the lights lets the stragglers catch up. In a way this turns 100 cars into one rather long car, which is easier to interleave with all the other long cars. This has been in place for over 30 years and is, I'm sure, a modeller's delight.

I don't like the system, and all the stop-start can't be good for the old carbon footprint, but it is interesting to think about. It helps me be a bit philosophical while waiting at another "pointless" red. We have lately been building expressways too — real eastate is still too expensive for roads, but tunnelling has become more affordable.

Was interestest to see what you both said about UK variable speed limits. They really change them and start photo-fining immediately? A bit harsh. We have the opposite problem here, where there is little/no enforcement of the speeds and many people sail on at their accustomed speeds. I have a feeling the traffic managers respond by posting even lower limits which even more people ignore. Except for the odd fastidious one (perhaps down to the last points on his licence) , so you have some doing 120kph and others doing 40. Not ideal.