Alternating 3 LED project
This is very simple LED chaser circuit 

Use a 74HC4017 for more drive current.   

What you do is use multiple LEDs for each color.
Only one will be on at any given time.

LED1-4 Red
LED5-6 Yellow
LED7-10 Green  



You could do something more like this: 

Yellow 1  LED 1-2
Yellow 2  LED 3-4
Yellow 3  LED 5-6
Green     LED 7-10  





If you want high driver current add a buffer driver or inverting buffer