Re: Traffic lights
They have all this technology and IMHO it's not implemented correctly
That's your opinion. The junction designers will, obviously, disgree.
you will notice a vehicle at the lights say 200 yards ahead and the lights go on green but by the time you get there it's back to red, no vehicle has come onto or through from the junction from either side
This is frequently the case if you are trying to drive between lights above the speed limit[1]. It is deliberate.
can't we have a system that sees say ten cars on the main road and two on the minor road and adjust the lights accordingly?
Yes, you can. And, moreover, you've got it. Junctions have counted cars and measured approach speeds for *decades*. The behaviour you are seeing is almost certainly the behaviour the designer wanted. There might well be a good reason for him wanting something different to what you want.
This road is a particular pain in the bum as the speed limit on parts of it have been reduced to 40 MPH because of a few pedestrian accidents and at least one bicycle death.
If you've got pedestrians and bicycles on the road, that really doesn't sound unreasonable to me. Have a go at walking/cycling along a road with traffic coming past you at 60mph - it's really not pleasant, especially when certain drivers can't estimate the width of their vehicles as well as they think they can[2].
It's a three lane road in some places FFS the same as most motorways
It's very different from a motorway. A motorway is entirely populated with performance motor vehicles driven by trained and qualified drivers.
If traffic lights were clever and detect that one side of the junction was far busier than the others it could instead of just being on a timer and adjust accordingly, maybe this already exist to a degree but I've never seen it in action
It is probable that every major junction you've seen in the last 40 years or so has done exactly that - you will usually see at least two sets of tar-filled trace cuts in the road (diamond or rhomboid depending on manufacturer) and often IR and doppler sensors on the signal head. That this system gives different control signals to the ones you want might give you pause for thought.
Disclosure: yes, I've worked in this industry.
Vic.
[1] I've seen - and made - many claims that the target speed is actually less than the speed limit. I cannot confirm that it is so - but that might be appropriate at highly-congested times, when a small reduction in speed leads to a large increase in throughput.
[2] I was walking along the road in Lymington a couple of weeks ago, and actually had to jump into the hedge twice to avoid being hit by vans. It is time for motorists (including me) to be held accountable for their actions...