The first numeric speed limit for automobiles was the 10 mph (16 km/h) limit introduced in the United Kingdom in 1861.

The present highest posted speed limit in the world, 160 km/h (99 mph), applied on two motorways in the UAE.
1) Abu Dhabi – Al Ain Rd
2) Sh. Khalifa Highway

In general, most countries follow speed limits less than 130 kph.

Map of highest-posted speed limits around the world. Note: UK and US use mph (“SPEED LIMIT xx”); elsewhere km/h (in circle).

The largest highway network on the planet

The US interstate is the largest main highway network totaling 76,640 km (47,622 mi). It is equal to roughly 2 laps around the equator.

The total length of all roads in the US is 6.58 Million km (4 Million mi). It is equal to roughly 8.5 times the return trips to the moon.

1. RED light is scattered the least by air molecules
2. RED has the highest wave length and can travel longest distance through fog, smoke, etc.
3. RED is associated with “danger” as it is color of blood

It is originated in UK from semaphores used at rail roads.

How pedestrian WALK and DON’T WALK signals evolved?

1. Separate Pedestrian Phase: In 1930, all 4 approaches of the intersection had a separate phase so pedestrians can walk in all directions including diagonally

2. RED-YELLOW-GREEN-WHITE: 4th signal indication of white with black background for pedestrians to cross the intersection

3. WALK and WAIT: MUTCD (USA) was first to implement WALK and WAIT signals at the intersection corners

4. WALK and DON’T WALK: In 1961, MUTCD removed WAIT as it easily be mistaken as it resembles WALK letters and followed DON’T WALK