Definition

The crossroad is a 4-way intersection. Cross traffic system was named after its cross shape when the intersection is viewed from the top. It had 3 generations.

The 1st generation used reflections. The signals for turning left and right were completely dependent to each other. When the vehicles on 1 side will turn left, the vehicles on its adjacent side will turn right. The signals for pedestrians and straight-going vehicles were the same because pedestrians cross beside the straight-going vehicles. This idea of using 1 signal for 2 functions limited the number of signals to 24, which saves some energy for the traffic lights. The 3 basic signals were stop, caution, and go.
Reference video: http://www.youtube.com/watch?v=FYXrvhha5Ng

The 2nd generation resembles the shape of a Christian cross. Another feature was the use of diagonal turning arrows in order to avoid confusion with the stop signal. This feature was based from the idea of drawing a line passing through the center of the road on a path parallel to the movements. Blinking signals were also used to indicate legality for that specific function when there is no conflict with other movements. However, the system became confusing because drivers misunderstood the signals.

The traffic lights only used Philippine flag colors: yellow, blue, white, and red. 

Each of the 6 road signals indicated a traffic signal:

- no entry (horizontal line) = stop (red)

- warning sign = caution (yellow)

- diagonal left arrow = turn left (blue)

- straight arrow (vertical line) = go straight (blue)

- diagonal right arrow = turn right (blue)

- distance indicator = countdown timer (white)

This idea of using 'animated' road signs prevented Filipino drivers from violating traffic rules by using road signs as traffic signals.

Reference video: http://www.youtube.com/watch?v=x9VH2EQkXI8

The 3rd generation combines the ideas from the 1st and 2nd generations. Coincidentally, 3 is the sum of 1 and 2. Both mathematical symbols are significant because they were formed by intersecting the straight lines to form an addition sign and the diagonal lines to form a multiplication sign. Respectively, the addition and multiplication signs are used for straight and turning movements. 1 traffic signal is equivalent to 3 'circles'. There are 18 circles in all. So, there are 6 signals. This idea of using mathematical signs further reduced the number of traffic signals from 24 to 6. The efficiency is increased by 300% or simply quadrupled.

HIStory

The original traffic system had only 2 cycles. They were only intended for straight movements.

However, the number of cycles became 4 due to the 2 cycles for turning movements.

Even if there are other cycles where straight and turning movements happen at the same time, the STOP time is still thrice the GO time.

The following suggested systems change the stop-go time ratio from 75:25 to 50:50. In other words, the STOP and GO time would be equal again! Each type of intersection has an appropriate traffic system:
- Continuously Flowing Intersection for wide intersections without infrastructures:
http://continuouslyflowingintersections.blogspot.com/
- Diverging Diamond Interchange for wide intersections with existing infrastructures:
http://divergingdiamondinterchanges.blogspot.com/
- Cloverleaf Interchange for narrow intersections in village roads:
http://cloverleafinterchanges.blogspot.com/
* The infrastructures refer to underpasses or overpasses, such as flyovers and tunnels.