The double diamond traffic interchange is more efficient for road traffic

Impetus

France invented the double diamond interchange (DDI) in the 1970s, and it has been copied in the US and other countries subsequently, with success.

It costs half the price of a typical conflict interchange (either roundabout or traffic light controlled ‘cross road’). It only requires two phases – (Ireland’s cities are choking with the number of phases in traffic signal systems) – eg no pedestrians crossing while ‘one fumes’ at a red light or three cars get through on a green light and it turns to red. Designed by deadwood, who receive their salaries and later their pensions without risk, irrespective of their performance.

Ideally, the two phase traffic lights on a DDI interchange, which should be controlled by video cameras and AI (artificial intelligence), rather than using the 40 year old design of the SCOOT* and SCATS** systems used in Irish towns and cities (Cork*, Dublin**, Limerick* and Waterford**). To put it in perspective, who uses Windows 3 today? Many people probably never heard of it. Why are the traffic signal control systems in Ireland so dated? The cost of this ‘datedness’ runs to hundreds of millions of EUR in time wasted, needless pollution, etc. Time for software/systems updating (and more emphasis on public transport use – together with more capacity please…)

Google satellite image of a DDI interchange n France. Obviously one needs to reverse the arrows, signage and island shapes to accommodate driving on the wrong side of the road:

https://tinyurl.com/y65lhmmk

ancapailldorcha

Mod: Moved to infrastructure.

L1011

Your comparison of a software family to a software version is fallacious. Windows is from 1985 and must be seen as 34 years old when you use your family logic. Both SCOOT and SCATS are updated/upgraded and are not the product released on day 1 anymore

The main line of business system my employer uses was released in its original form in 1978 but I suspect you'd have severe trouble taking a 1978 user and parking them in front of the multiscreen GUI it has become.

Any new system is likely to run on a UNIX-like platform - those are from the 1960s by your first logic!

vrusinov

Unclear whether double diamond has any advantages over dumbbell which is very common here.

If you are comparing against regular diamond - then maybe? double one requires wider bridge and it seems like it's less compact. There is some criticism here: https://www.citylab.com/design/2011/11/diverging-diamond-interchange-abomination/453/ although it is not clear whether it's design problem or just a crappy implementation.

HonalD

Impetus wrote: »

France invented the double diamond interchange (DDI) in the 1970s, and it has been copied in the US and other countries subsequently, with success.

It costs half the price of a typical conflict interchange (either roundabout or traffic light controlled ‘cross road’). It only requires two phases – (Ireland’s cities are choking with the number of phases in traffic signal systems) – eg no pedestrians crossing while ‘one fumes’ at a red light or three cars get through on a green light and it turns to red. Designed by deadwood, who receive their salaries and later their pensions without risk, irrespective of their performance.

Ideally, the two phase traffic lights on a DDI interchange, which should be controlled by video cameras and AI (artificial intelligence), rather than using the 40 year old design of the SCOOT* and SCATS** systems used in Irish towns and cities (Cork*, Dublin**, Limerick* and Waterford**). To put it in perspective, who uses Windows 3 today? Many people probably never heard of it. Why are the traffic signal control systems in Ireland so dated? The cost of this ‘datedness’ runs to hundreds of millions of EUR in time wasted, needless pollution, etc. Time for software/systems updating (and more emphasis on public transport use – together with more capacity please…)

Not sure how extensive your knowledge of traffic signalling systems are but I look forward to the "Grade Separated Interchanges are more efficient for road traffic" thread...

CelticRambler

Impetus wrote: »

France invented the double diamond interchange (DDI) in the 1970s, and it has been copied in the US and other countries subsequently, with success.

It costs half the price of a typical conflict interchange (either roundabout or traffic light controlled ‘cross road’).

Hmmm. If DDI is so much better than a roundabout, why have so many French cities, towns and villages built so many roundabouts in the last decade? On some of the long-distance routes I've travelled regularly in that time, there would be around 100-150 new roundabouts (usually clusters of 5-10 on a ringroad/by-pass)

I don't think I've ever driven on a DDI* ... but I frequently sit for ages at a red light (in France) while the lights cycle through their sequence for the non-existent traffic on the other roads. :rolleyes:

Edit: I've driven under the bridge in your example a few times.