Why roundabouts are cool

[Infinitum80 12]

I know I have said this in another thread but wanted to really "drive" it home

 

 

In a typical road junction managed by traffic lights, the lights come on and off in a timed sequence that is in real life forecast based on traffic patterns but ultimately uses a timer to determine traffic.

 

This means that if Road A has 100 cars queing and Road B has 10 cars queing and the Traffic Light alternates on a 30 second window, and each car takes 2 seconds to pass through the junction, 15 cars can go through the junction at any point.

 

This means that Road A will only allow 15% of its queing cars to evacuate the junction whilst Road B allows the entire queue to leave with 10 seconds left over.

 

In this specific scenario those 10 seconds (approx 16% of the total sequence) is lost.

 

 

 

This is only a specific scenario, real life / sim life may allow for more or less queue, different sequences etc etc but the concept remains the same which is that without some kind of constant calculation of the traffic second to second, time is lost with a typical traffic light system unless all traffic is 100% equal (which usually means 100% gridlock!)

 

 

 

 

A roundabout however DOES utilize constant calculations in real life, with the control being down to the drivers and their eyes/brains and common sense.

 

 

In the above example, roughly and not exactly the waiting time is shared out amongst all parties and whilst the variations do alter based on which direction the traffic wants to go, the confidence of the drivers etc it ultimately means very little if any time is spent waiting at junctions.

 

 

 

Bottom line - bring roundabouts to SC please!

[strokesboy21 11]

being a brit i would love the option of roundabouts being added

[Joe 90 358]

...some kind of constant calculation of the traffic second to second, ...

As a heap of my fellow engineery-types will no doubt point out, in real life this is exactly what happens. Traffic lights are hooked up to sensors and can adjust their phase lengths to account for queued traffic on a red, or a continuous flow on green, both, or neither. When used dynamically, lights are definately more efficient than roundabouts. Roundabouts are useful though as an intermediate step between a priority intersection (low volume) and lights (high volume).

However, from what I've seen in SC to date, roundabouts won't do a thing to those traffic jams.

[servius 11]

Cool text!
txs

[viviancyu 7]

...some kind of constant calculation of the traffic second to second, ...

As a heap of my fellow engineery-types will no doubt point out, in real life this is exactly what happens. Traffic lights are hooked up to sensors and can adjust their phase lengths to account for queued traffic on a red, or a continuous flow on green, both, or neither. When used dynamically, lights are definately more efficient than roundabouts. Roundabouts are useful though as an intermediate step between a priority intersection (low volume) and lights (high volume).

However, from what I've seen in SC to date, roundabouts won't do a thing to those traffic jams.

 

Exactly this. Most traffic lights are hooked up to induction loops or cameras that can monitor for vehicles and queue lengths. It's rare that a busy intersection would have manual timed signals anymore. Roundabouts are certainly preferable to stop-controlled intersections, and they work well in low capacity, but at higher capacity or places where there's a great differential between cross roads traffic, it's better to have lights.

 

I would love to see SC have roundabouts, and I've seen some designs where people just... lay roads down to look like roundabouts, but as far as I can tell there's no "yield" in SC traffic so I'm not sure how real roundabouts could actually be implemented.

[Infinitum80 12]

Really? Well i suppose that works in the US or outside the UK but I am fairly sure that the lights I run into have no consideration of sensors.

Sometimes I have got really bored and counted how long until the lights change - and this doesnt vary

 

I reckon it will change depending on recorded and forecast data (ie different at peak time, different if there is a football game on) but I do not think that in the UK we have a lot of these smart-traffic lights or not at least that I have run into.

 

Either way, a roundabout is the smartest form of traffic control since it allows for the exact traffic scenario to be judged each tiem

 

And becuse of this you would think there are more accidents on roundabouts when in fact they save more lives in their placement than they cause.

 

 

Near our house there is a small T junction where the tail part connects to a supermarket. Getting in and out of this used to be a nightmare because to get out I would head up the tail of the T and turn right to get home but to do that I would need to cross over the traffic which required me to have no traffic coming from the right or left.

 

So in this situation for traffic to flow it has to wait for there to be a natural gap between two independent lanes of traffic going opposite ways where the t-bar of the junction has priority and doesnt suffer this problem.

 

Now we have a roundabout and its seamless and there are no problems or heavy queues.

 

 

 

 

Why dont they just have a soft-key that lets you pain roundabout junctions. I dont know the maths but i reckon if someone compared a typical gridlocked 4-way junction to a roundabout offering the same exits that it would allow traffic to flow smarter than any traffic light would.

 

 

And overpasses... why cant we have these? even if you add terraforming so we can make it go through a tunnel or something.

Why does the busy hectic stupidly busy because pathfinding is broken road have to intersect with my breezy not as busy intersection?

 

 

One thing i realized is... why can't Maxis/EA just come out and say "We have a buggy game, we are sorry however we want to institute some kind of community development and as a result tailor the game to suit what the community want. We are going to have 5 things every month we want to change (either they come up with them, see the interest from the forums or ask directly for feedback) and then you can vote on what you want"

 

That way if the people know that each month something they want will be added (ie roundabouts, overpasses, subways etc) then it will actually be a joint venture rather than EA bleeding us

[Panos 29]

I know there aren't any roundabouts as such atm. But I am experimenting with closed round roads. I found that the traffic splits between the roads evenly because you can go both right & left (since they are roads and not single traffic direction). 

 

Is weird how they move, but it does feel the traffic is moving faster than when I had X or T on those junctions. But because they are roads, they take a lot of space and they are big.

 

 

So yes we need roundabouts and single direction road traffic with the ability to remove stop signs on some roads and give priority to others. 

[JimCityBuilder 14]

I would like to know why there are no motorcycles in the new Sim City ? Many people in the real world commute on motor bikes and traffic filtering would go a long way to reucing traffic grid locks too ... just my opinion !

[MOWS 4 U 169]

I know I have said this in another thread but wanted to really "drive" it home

 

 

In a typical road junction managed by traffic lights, the lights come on and off in a timed sequence that is in real life forecast based on traffic patterns but ultimately uses a timer to determine traffic.

 

This means that if Road A has 100 cars queing and Road B has 10 cars queing and the Traffic Light alternates on a 30 second window, and each car takes 2 seconds to pass through the junction, 15 cars can go through the junction at any point.

 

This means that Road A will only allow 15% of its queing cars to evacuate the junction whilst Road B allows the entire queue to leave with 10 seconds left over.

 

In this specific scenario those 10 seconds (approx 16% of the total sequence) is lost.

 

 

 

This is only a specific scenario, real life / sim life may allow for more or less queue, different sequences etc etc but the concept remains the same which is that without some kind of constant calculation of the traffic second to second, time is lost with a typical traffic light system unless all traffic is 100% equal (which usually means 100% gridlock!)

 

 

 

 

A roundabout however DOES utilize constant calculations in real life, with the control being down to the drivers and their eyes/brains and common sense.

 

 

In the above example, roughly and not exactly the waiting time is shared out amongst all parties and whilst the variations do alter based on which direction the traffic wants to go, the confidence of the drivers etc it ultimately means very little if any time is spent waiting at junctions.

 

 

 

Bottom line - bring roundabouts to SC please!

Let me start by saying that MANY traffic lights do not work on timers alone...  They use a system of pressure pads to determine where and how much traffic there is and adjust light sequences accordingly. 

 

Secondly, although roundabouts are indeed more efficient than traffic lights in some instances in heavily congested areas they are not.  I live in Hilliard, Ohio, where they've recently decided to sprinkle roundabouts around everywhere (BTW in drivers ed there is no mention of roundabouts, leading to much confusion from younger drivers and the elderly) and most of them work perfectly.  However when they removed the two busiest intersections in town and replaced them with roundabouts it did no good.  You can still expect to spend 30-40 minutes in line before reaching the roundabout during rush hour.  The traffic in SimCity will almost certainly face the same difficulties.

 

In short, roundabouts aren't a "magic" solution for traffic congestion (although I do quite like them).

[Joe 90 358]

Really? Well i suppose that works in the US or outside the UK but I am fairly sure that the lights I run into have no consideration of sensors.

Sometimes I have got really bored and counted how long until the lights change - and this doesnt vary

 

I reckon it will change depending on recorded and forecast data (ie different at peak time, different if there is a football game on) but I do not think that in the UK we have a lot of these smart-traffic lights or not at least that I have run into.

 

Either way, a roundabout is the smartest form of traffic control since it allows for the exact traffic scenario to be judged each tiem

 

And becuse of this you would think there are more accidents on roundabouts when in fact they save more lives in their placement than they cause.

 

 

Near our house there is a small T junction where the tail part connects to a supermarket. Getting in and out of this used to be a nightmare because to get out I would head up the tail of the T and turn right to get home but to do that I would need to cross over the traffic which required me to have no traffic coming from the right or left.

 

So in this situation for traffic to flow it has to wait for there to be a natural gap between two independent lanes of traffic going opposite ways where the t-bar of the junction has priority and doesnt suffer this problem.

 

Now we have a roundabout and its seamless and there are no problems or heavy queues.

I'm pretty sure most UK lights are dynamic too - there's no reason not to have them. You can sometimes see the sensors in the road too. Around here we use induction loops and you can often see rectangular marks on the road where the wires have been embedded in the asphalt.

Consider this for your supermarket - you are exiting the supermarket at rush hour, and there is a constant stream of traffic passing through the roundabout which has priority over you. How long do you wait? Forever? That's probably the simplest scenario where RABs completely fall over. Lights will still often take 10-20s to change once they 'notice' you, depending on how much traffic is going through. Most max out at about 90s (which can feel like an eternity but isn't).

[SkywalterDBZ 0]

Also, some lights in the US, even the ones with sensors will sometimes INTENTIONALLY stifle traffic flow with unnecessary red lights. This is usually limited to side streets to act as a psedo stop sign or during late night / early morning hours (12AM-5AM), to prevent people from speeding on long straightaways with a string of green lights. In fact I remember one avenue sized road near where I used to live, where at night every light for the avenue was kept red non-stop (green lights were kept on for empty parking lots of businesses closed for the night) until it detected a car, then in about 5 seconds would turn green and almost immediately turn yellow as you began to accellerate so as to ensure any other late night traffic would stop.

[Zades 7]

I would like to know why there are no motorcycles in the new Sim City ? Many people in the real world commute on motor bikes and traffic filtering would go a long way to reucing traffic grid locks too ... just my opinion !

 

There are?

 

[stringerbell 9]

Also, some lights in the US, even the ones with sensors will sometimes INTENTIONALLY stifle traffic flow with unnecessary red lights. This is usually limited to side streets to act as a psedo stop sign or during late night / early morning hours (12AM-5AM), to prevent people from speeding on long straightaways with a string of green lights. In fact I remember one avenue sized road near where I used to live, where at night every light for the avenue was kept red non-stop (green lights were kept on for empty parking lots of businesses closed for the night) until it detected a car, then in about 5 seconds would turn green and almost immediately turn yellow as you began to accellerate so as to ensure any other late night traffic would stop.

I would hate to live in that town. Few things in life irritate me more than having to sit at a red light when I'm the only damn car on the road in the middle of the night

[JimCityBuilder 14]

I would like to know why there are no motorcycles in the new Sim City ? Many people in the real world commute on motor bikes and traffic filtering would go a long way to reucing traffic grid locks too ... just my opinion !

 

There are?

 

Surely that's just a scooter ... lol. yep I noticed one riding around yesterday