I've been thinking about how pretty much no USA infrastructure of today is as reliable as of the last half of the 20th century. Just my imagination, or true? And what does it mean?
Airliners crash far less, road fatalities kept going down till 2010, so taking the broad view of were infrastructure is I’d say at least those got better.
Anecdotally, I remember more electricity interruptions and plumbing issues when I was a kid, but that could be location dependent and I couldn’t quickly find good numbers going back that far.
Edit:
While the phone network didn’t necessarily go down, I frequently got “all circuits busy” when I was a kid. I don’t remember the last time that happened.
I wish we had metrics for utility companies. In my midwestern experience, things have gotten worse. I don’t remember any outages as a kid in the 90s that were over 24 hours aside from the major blackout in the early 2000s. As an adult I’ve experienced several outages greater than 24 hours in both summer and winter months. It’d be nice to be able to measure this.
In USA for example, road design AND vehicle design is directly linked and beholden to NHSTA regulations and policies.
Infrastructure (IE State route roads) are ever trending towards wider lanes and more gentle shoulder. This is precisely due to vehicle industry requirements requiring more vehicle safety features (and thus width and length), height, and shoulder level clearance @ windows.
All these infrastructure and endpoint changes are driven "organically" by the USA trend towards SUVs, but mainly driven by insurance requirements. Insurance and gov't "make out" on safer/roads/vehicles due to (perceivabally) less accidents and road maintenance.
I can't speak to airplanes, but I imagine the fact that far, far, far more people are able to fly today than even 25 years ago should show that the infrastructure has drastically improved.
And tangentially related, it was much easier for anyone to eavesdrop on your conversations.
When it rained, I could pick up my phone and hear conversations from my neighbor on my landline and talk to them without calling.
Not to mention if you were in the same house, you could surreptitiously here conversations by just picking up the phone or getting a device from radio shack that didn’t have a microphone, that you could plug in to another phone outlet.
With analog cellular, you could also buy a receiver from Radio Shack and hack it to pick up the unencrypted signals from cell phones.
Redundancy was needed because individual nodes/machines were more prone to failure. As machines got more and more reliable, having highly redundant infrastructure was seen as an extra cost.
Yes. Electromechanical switching systems were substantially more reliable than their components. How this was done should be understood by anybody designing high-reliability systems today.
"A History of Science and Engineering in the Bell System - Switching Technology 1925-1975" is a readable reference. The Internet Archive has it.[1]
More hardcore: "No. 5 Crossbar"[2]
The Connections Museum in Seattle still has a #5 Crossbar working.[3] Long distance used toll switches, "#4 Crossbar", and there were 202 of them.
#4 and #5 Crossbar machines are collections of stateless microservices, implemented from electromechanical components. The terminology is used in the old books is completely different, but that's what they are. Each service always has at least two servers. The parts that do have state are distributed. The crossbar switches that make actual connections have state, but are dumb - they are told what to do by "markers", which are stateless but can read the state of the crossbars and of other components. Failure of a single crossbar unit can take down less than a hundred lines at most. Other than the crossbars to external lines, everything had alternate routes. Everything has fault detection, with lights and alarm bells.
Error rates were fairly high. In the previous "step by step" system, a good central office misdirected about 1% of calls. With bad maintenance (and those things were high maintenance) that could get much worse. Crossbar was better, maybe 0.1% misdirected calls.
Routing tables in crossbar were mostly static ROMs of one kind or another. Routing consisted of trying a predetermined set of routes, in order. Clunky, but reliable.
Highway construction standards are much higher than they were 30-50 years ago, but it's a mixed bag. Administrative costs are significantly higher. Survey has dramatically improved with GPS. Highway engineering has not improved since about the 90s. Automated machine guidance has significantly improved the potential accuracy of grading operations in th last decade.
It depends on you view this. If you measure by total bit / data / time per customer served divided by the total outage time I would think we are still very reliable in terms of telecoms. It is worth remember we are likely serving 1 to 100 million times of what we did on mobile network 30 years ago.
Just purely in terms of total downtime itself we are less realible. Purely because of the complexity involves.
