Your welcome...
Here is a little video of it 
Why does it go back to Yellow after Red?
Shouldn't it be Green, Yellow, Red, Green,...
Is the Pedestrian signal for the cross street?
Here, the Pedestrian signal goes Walk, flashing DontWalk, DontWalk.
The author of the book "Begining Arduino" by Micheal McRoberts is from the UK. Their traffic light system is different than Noth American system. ( Assuming the traffic light system in New-York City is the same in Toronto )
How is one to "interpret" the G-Y-R-Y-G...?
The Yellow after Red == "get ready to go, but, beware ?
Apparently the plan is to make mandatory this flashing-yellow arrow arrangement for left turns - in a four-section signal there'll be two yellow arrow indications, one will flash and the other won't.
Red-Green Arrow, flashing yellow arrow (== Green through), solid yellow arrow, Red.
? ? ? ?
I know it look comfusing... :~ I do drive for a living...
The Yellow after Red == "get ready to go, but, beware ?
Must be it... 
In Toronto is : G - Y - R - G - Y - R ------- standard traffic light. Simple
Apparently the plan is to make mandatory this flashing-yellow arrow arrangement for left turns - in a four-section signal there'll be two yellow arrow indications, one will flash and the other won't.
You may be right. The traffic light is a UK system.
Techone:
Well, can you show us : Schematic, circuit setup and code.My test code is simple. It is just a Blink, but using multiple leds. 150 ohms is a bit high. Use 330 ohms or 470 ohms. Check the led polarity : cathode and anode. Check where the ground wire is, and the digital output pins are wired. My code is design to check the leds and connections... Checking the hardware basicaly.
Is 150 ohms to low?
I calculated it with the formula: (Vsupply-Vled) / Iled, so (5v-2v) / 0.020A = 3v / 0.020A = 150ohms.
btw: How can I type an indice, for exemple if I want to type R2, and make the 2 go right under the R. Like in this picture:
[quotebtw: How can I type an indice,][/quote]
That, I don't know... :~
Is 150 ohms to low?
I calculated it with the formula: (Vsupply-Vled) / Iled, so (5v-2v) / 0.020A = 3v / 0.020A = 150ohms.
It is not 150 ohms is too low, it the 20 mA is the problem. It is 50 % lower than the max rated of the Arduino chip 40 mA. I am not confortable with it... I always use 470 ohms.
5 - 2 / 470 = 6.383 mA is much safer than 20 mA..... in my opinion. That current value, I am comfortable with it.
Ok no problem 
I'm trying to calculate the resistor for my bright leds, but I don't know the max current and voltage of it.
Do you know what the max current and voltage is for a normal bright led?
It depend. Check the datasheet of the led. Some type are 10 mA, 20 mA, 2 Vled, 3 Vled, 1.8 Vled....If you REALLY want to go for MAX value of an led, pass 20 mA, well use a transistor to control the led. With a base resistor of 1 K to 4.7 K, that will be safer for the Arduino digital pin and the transistor will switch the led with at higher current. If something goes wrong, the transistor will be "bye--bye" not your Arduino.
Here a picture.
Thank you for the tip!
Hello All
There is an error webpage for this book at...
Look under the "ERRATA" Tab
You can also download the source code
at the same place, its a zip file.
For this project, the error sheet says.....
On page 41:
add
near the end of project_4
following this line:
digitalWrite(carYellow, LOW); //yellow off
.
.
add this missing line:
digitalWrite(pedRed, HIGH); //ped red on 9
It seems to me that anyone can post a correction...
At this point, I'm working on project 6, Interactive LED Chase Effect.
I'm very new to Ardunio. I do like this book very much.
Thanks,
Allen Sklar
Tempe Arizona, USA