Kits are available for this project from Talking Electronics for $20.00 for the parts and PCB plus $5.00 for each overhead light (4 needed) plus $6.50 postage.
The project is also available fully assembled and tested for $25.00 plus postage.

This project adds realism to your layout with functioning traffic lights at an intersection.
You can use column signals or overhead signals.
The PC board shows the condition of the lights and you only need to extend leads from the board to the signals, to complete the project.
The supply MUST be 12v as the voltage of the LEDs adds up to about 10v and any voltage below 12v will not allow some of the LEDS to illuminate AT ALL - and you will think the project is faulty!
The module comes with 2 extension leads and on the end of each lead is 8 machine pin sockets.
The traffic lights supplied with this module have 4 very fine wires:
black - red - yellow - green
The black wire is the common wire to the 3 LEDs.
It goes down the hole shown in the third photo. The other colours are “R” (red) “O” (orange) “G” (green)
The extension leads are marked with either a red lead or white dot on the side of the socket.
Connect an extension lead to the 4 screw terminals and push a fine wire from the traffic light into the machine pin and then push a short length of 0.25mm tinned copper wire into the hole to keep the lead in place.
If you have a soldering iron, solder a short length of 0.5mm tinned copper wire to each of the fine leads and then push them into the machine pins.
This module is quite complex. It is fully guaranteed and if you have any problems, you can contact Colin Mitchell: colin@elechelp.com

This wiring diagram shows how the LEDs are connected in the over-head light. All the anodes are connected to the black wire and the cathodes emerge as Green, Orange and Red. The 4-screw terminal block is looking at the where the wires enter the terminals and this is clearly shown in the photograph above.