How many traffic lights are there?
How many traffic lights are there?
about 300,000 signalised intersections in the United States
Retiming existing signals typically cuts delay by 10 to 20% at a cost of a few thousand dollars per intersection, which makes it one of the cheapest transport interventions there is.
The United States has roughly 300,000 signalised intersections — the figure transportation engineers use, and it counts intersections rather than individual signal heads, of which there are several million. No comparable global count exists. What is measured instead is how badly they are run: the national traffic signal report card has repeatedly graded US signal timing at a D, largely because most agencies retime signals only every five to ten years while traffic patterns change continuously.
How the figure is arrived at
Surveys of state and local transportation agencies, who own the signals and hold asset inventories for maintenance purposes. There is no central register, so the national figure is a scaled-up survey response rather than a count, and estimates range from 280,000 to 330,000.
How confident it is
- Low estimate
- 280,000
- High estimate
- 330,000
- Spread
- 1.2× between the bounds
Other things people built counts
- How many countries are there in the world? 195 — or 193, or 206, or 249, depending on who is counting
- How many cars are there in the world? about 1.5 billion motor vehicles
- How many planes are in the air right now? roughly 10,000 to 20,000 at any moment
- How many languages are there in the world? about 7,150 living languages
- How many McDonald's are there? about 43,000 in over 100 countries
- How many phones are there in the world? about 8.9 billion mobile connections — more than there are people
- How many nuclear weapons are there? about 12,200 warheads
- How many websites are there? about 1.1 billion hostnames — but only around 200 million active
- How many books have ever been published? about 130 million as of 2010 — probably over 200 million now
- How many airports are there in the world? about 45,000 with runways — but only around 4,000 with scheduled airline service
- How many ATMs are there in the world? about 3 million
- How many cities are there in the world? about 10,000 with over 50,000 people; 33 megacities over 10 million
- How many buildings are there in the world? somewhere between 1.5 and 4 billion
- How many computers are there in the world? roughly 2 billion personal computers in use
Common questions
- How many traffic lights are there?
- about 300,000 signalised intersections in the United States
- How is that estimated?
- Surveys of state and local transportation agencies, who own the signals and hold asset inventories for maintenance purposes. There is no central register, so the national figure is a scaled-up survey response rather than a count, and estimates range from 280,000 to 330,000.
Related pages
- How many countries are there in the world? 195 — or 193, or 206, or 249, depending on who is counting
- How many cars are there in the world? about 1.5 billion motor vehicles
- How many planes are in the air right now? roughly 10,000 to 20,000 at any moment
- How many languages are there in the world? about 7,150 living languages
- How many McDonald's are there? about 43,000 in over 100 countries
- How many phones are there in the world? about 8.9 billion mobile connections — more than there are people
- How many nuclear weapons are there? about 12,200 warheads
- How many websites are there? about 1.1 billion hostnames — but only around 200 million active
- How many people are there in the world? Living things and the natural world
- How many stars are there in the universe? Space and the universe
- How many bones are in the human body? The human body
- How many grains of sand are there on Earth? Living things and the natural world
- How many ants are there in the world? Living things and the natural world
- How many trees are there in the world? Living things and the natural world
Sources
- Typical range compiled from manufacturer specifications — At One Place