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Author Topic: Traffic signals: yellow lights  (Read 3863 times)

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Offline Isaac.Eiland-Hall us

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Traffic signals: yellow lights
« on: December 14, 2009, 02:05:38 PM »
Now that we have control over the timing of traffic signals, I know I'll be using them a lot more.

Simplest form of this request: Switch out the green light for a yellow light one second before it turns red. (of course it would be up to graphic designers to paint this; could make the dat line optional - if it exists, switch to yellow one second before red; otherwise, just go to red)

Slightly more complicated: It'd be cool to have control over the length of the yellow, just like the length of the green now in both directions (in the nightlies) - a simple number like those are that means "n seconds of yellow". That way, each individual light could have its own settings (should allow 0 as valid)

I'm planning on posting elsewhere about simulating an international border crossing using traffic lights - in that case, having no yellow is desirable. :)

Offline jonasbb

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Re: Traffic signals: yellow lights
« Reply #1 on: December 14, 2009, 03:15:57 PM »
Interesting idea. Should the yellow have some special function?

Offline Isaac.Eiland-Hall us

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Re: Traffic signals: yellow lights
« Reply #2 on: December 14, 2009, 03:19:26 PM »
The only think I can think of, which would be nice, would be for traffic approaching a yellow to slow to a stop (like trains do for stations)...

Offline prissi

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Re: Traffic signals: yellow lights
« Reply #3 on: December 14, 2009, 08:06:30 PM »
But there are the german and the autrian and thousand different kinds of traffic lights.

German ("Formula 1"):
Red
Red+Yellow
Green
Yellow
Red

Austria and some other countires:
Red
Red+Yellow
Green
Green flashing
Yellow
Red

Japanese:
Red
Green
Yellow
Red

and so on ...

Before I want to open this can of worms, I just though to keep it like now, since yeloow has not advantages I easily see.

Offline rsdworker

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Re: Traffic signals: yellow lights
« Reply #4 on: December 14, 2009, 08:19:11 PM »
in england - its like in japanese but some signals have

red
green
yellow
red

at some crossings - the sequence is different the crossings that user has press the button

red
yellow - flashing
green
yellow
red

the older signals (built before 1999) have

red
red+yellow
green
yellow
red

i can't remember i saw some had like this which skips yellow when changing back to red

red
yellow
green
red

in holland - there amber light flashing at night time
« Last Edit: December 15, 2009, 01:23:21 AM by rsdworker »

Offline IgorEliezer br

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Re: Traffic signals: yellow lights
« Reply #5 on: December 15, 2009, 01:06:10 AM »

Offline rfg123

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Re: Traffic signals: yellow lights
« Reply #6 on: December 15, 2009, 01:28:19 AM »
In most of the US we
in england - its like in japanese but some signals have

red
green
yellow
red

Same for the US, although some cities use flashing green 3 seconds before yellow.

As for finding a purpose for the yellow light.. I would make it the same function as stop, that way vehicles do not venture out in the intersection as waiting vehicles are given the green. Too bad sensor pads cannot be replicated in game, where busy roads will always have the green light over smaller less trafficked roads until a vehicle pulls up to the stop line and triggers the cycle.

Offline skreyola

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Re: Traffic signals: yellow lights
« Reply #7 on: December 15, 2009, 01:48:24 AM »
green. Too bad sensor pads cannot be replicated in game, where busy roads will always have the green light over smaller less trafficked roads until a vehicle pulls up to the stop line and triggers the cycle.
That is the main reason I pretty much never use traffic signals in my games. Timed signals always cause unnecessary delays, in my experience. If we could have on-demand signals, that would be awesome.

Offline Fabio

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Re: Traffic signals: yellow lights
« Reply #8 on: December 15, 2009, 10:51:19 AM »
German nodel is the best for drivers, i can't get why it isn't replicated in other countries as well...

Offline EvanBGood

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Re: Traffic signals: yellow lights
« Reply #9 on: December 15, 2009, 12:11:25 PM »
This may be common in all countries, but US also has blinking yellow and blinking red for off-hours. This may not make sense in Simutrans because there's no actual day/night commute cycle, but it might translate well as a traffic light that only stops traffic if X number of cars are approaching the intersection. That would simulate this "down" times, while avoiding the chance of a single truck waiting at an otherwise empty stoplight... which happens to me almost every day driving to work.

Offline KrazyJay

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Re: Traffic signals: yellow lights
« Reply #10 on: December 15, 2009, 06:16:24 PM »
German nodel is the best for drivers, i can't get why it isn't replicated in other countries as well...

During my study as traffic planner/engineer I asked that question as well. Basically, it's due to a mix of reasons.

1: Laws. It needs some changes in law to allow Red-Yellow.

2: Education: In case a country changes, it requires a change in educational books, trainings, courses, and so on. That's costly.

3: Safety. Every crossing is different. On every crossing it takes different times before a crossing is cleared. That could be the time it takes for a car to cross a traffic light and get beyond the crossing, but also buses and trucks need to be taken into account. A controlled crossing can not let certain traffic flows cross each other. So a traffic light needs to stay Red until another flow has cleared and is stopped by a Red light.

A given is that some drivers will start driving when a light is Red-Yellow, but some will wait. If Red-Yellow appears, the other flows that might obstruct must have been stopped by a Red light and cleared at that time already. When most countries go Red to Green, countries like Germany will go Red-Yellow instead of Green, not instead of keeping Red longer.

Example on a simplified 1 minute cycle:
Germany: Red 25s, Red-Yellow 2s, Green 28, Yellow 5s.
Common: Red 25s, Green 30s, Yellow 5s.

Bonus ;) : Some countries, like Belgium, use a "German" system for public transport, since trams and buses take longer to accelerate. For regular road traffic, they use a "Common" system.

When it comes to efficiency, there is not much difference, more efficiency can be reached by setting the cycles and it's timings well.

edit:

The Dutch Yellow blinking is to warm drivers about an "off-line" controlled crossing. Normal priority rules apply. In other countries it is also used during quieter moments. In Belgium there's even a difference between a Yellow blinking light on the middle (yellow) position and the Yellow blinking on the lower (green) position. In the latter case that light can be green (solid) or yellow (blinking). As some might expect, that's achieved with a yellow filter with a blue and a white light bulb and instead of a green filter with a white bulb. But the functions too far off-topic to explain.
« Last Edit: December 15, 2009, 06:21:31 PM by KrazyJay »

Offline skreyola

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Re: Traffic signals: yellow lights
« Reply #11 on: December 15, 2009, 08:19:11 PM »
In the States, blinking red does mean the traffic light is not acting as a controlled signal, but its meaning is described in the traffic instructions as something like 'to be treated as a stop sign'.
Blinking yellow, in the States, means caution (as someone may be coming off a side street that has a blinking red facing it), but in practice, it means to many drivers 'ignore the signal', that is, drive through without stopping or slowing.