Road junction

A road junction is where roads meet.

These spots help people go to towns. Sometimes, new towns grow near these spots.

Some roads cross at the same level. Other roads go over or under each other.

This helps many cars move at once.

We use tools to keep people safe. We use lights and stop signs. These help drivers know when to go.

People walking also use these spots. They use paths to cross the street. Some lights even make sounds for them.

Junctions help us travel to new places.

A road junction is a place where two or more roads meet.

In the past, roads linked towns and forts. Sometimes, new towns grew near these meeting spots. Travelers often give junctions names to help find their way.

There are two main types of junctions. At an intersection, roads cross at the same level. At an interchange, roads pass above or below each other. This is called grade separation. Interchanges use slip roads to help cars move.

Some interchanges use traffic lights. Others let cars flow freely without stopping.

Safety is very important at junctions. We use stop signs and traffic lights to manage cars. We also use lane controls to guide drivers. To help people walking, we use crosswalks and walk lights. Some lights make sounds for people who cannot see well. For people on bikes, we can build protected intersections. These use islands to keep riders safe from cars.

A road junction is a place where two or more roads meet.

These meeting spots are very important for travel. In the past, roads linked towns, forts, and river crossings. Sometimes, a new settlement would grow right where roads met. One famous example of this is Scotch Corner. Travelers often give junctions names to help them find their way. They might name a junction after a nearby business or a place of interest.

Managing how traffic moves through these spots is a big job. Engineers use different tools to keep people safe and reduce delays. First, they added traffic control devices like stop signs and lights. Next, they used lane controls to limit what each lane could do. Some turns might be banned to stop cars from crossing oncoming traffic. Today, special designs use math about speed and how many cars use the road.

There are two main ways roads can meet. At an intersection, the roads cross at the same level. These are called at-grade intersections. At an interchange, roads pass above or below each other. This is called grade separation. Interchanges use slip roads to help cars change paths. Some interchanges use traffic lights, like the diamond design. Others allow cars to flow freely, like a cloverleaf or a stack. In Germany, some four-way interchanges are called an Autobahnkreuz.

Safety is a major focus because junctions can be dangerous. In the European Union, junctions caused about 20% of road deaths between 2006 and 2015. Many of these accidents happen because a driver misses an observation. This could be because something is blocking their view. It could also be because of a human mistake, like being distracted. Sometimes a driver might misunderstand what another person is doing.

We also build junctions to help people walking and riding bikes. Pedestrians use crosswalks, walk lights, and even overpasses to stay safe. Some walk lights make sounds for people who cannot see well. For cyclists, engineers use protected intersections to keep them away from cars. These designs often use concrete islands to create a safe space. In the Netherlands, many bike paths are at least 2.5 metres wide. In Manchester, UK, they use a special design called a CYCLOPS junction. This helps cyclists and pedestrians cross the road more easily.

A road junction is a specific type of connection where two or more roads meet. These meeting points are vital for transport networks because they link important locations. Historically, roads connected towns, military forts, and geographic features like river fords. When roads met in areas without existing settlements, these junctions often led to the creation of new towns. Scotch Corner is a notable example of a location that grew from such a meeting point.

As road networks grew more dense, managing traffic flow became a major priority. Engineers work to minimize delays and improve safety for everyone using the road. Early innovations included traffic control devices like stop signs and traffic lights. Later, engineers introduced lane controls to limit what specific lanes could do. For example, some turns across oncoming traffic might be prohibited entirely. Modern junction designs now use complex data regarding traffic volumes and driver intent. This allows for specialized layouts that handle specific patterns of movement.

Junctions are categorized by whether roads cross at the same or different elevations. At-grade intersections occur when roads cross at the same level. Interchanges use grade separation, meaning roads pass above or below one another. These interchanges use slip roads to help vehicles transition between paths. While interchanges are more expensive to build, they offer higher throughput. Single-grade intersections are lower in cost but move fewer vehicles.

Interchanges are subdivided into many specific types based on their design. Signalized interchanges use traffic lights and include diamond designs. These can be regular, diverging, three-level, or tight diamonds. Other types include the single-point urban or the partial cloverleaf. Non-signalized interchanges allow for free-flow movement. Examples include the cloverleaf, the stack, and the windmill. Some non-free-flow designs use roundabouts, such as the dogbone or dumbbell. In Germany, four-way interchanges are called an Autobahnkreuz (AK). Three-way interchanges are known as an Autobahn Dreieck (AD).

Safety is a critical concern because junctions can be high-risk areas. In the European Union, junctions accounted for approximately 20% of road fatalities between 2006 and 2015. In 2015, about 5,000 of the 26,100 car crash fatalities in the EU occurred at junctions. Among these fatalities, 34% were car users and 23% were pedestrians. Motorcyclists made up 21% of these deaths, while cyclists accounted for 12%. Understanding these statistics helps engineers design safer systems for all road users.

Many accidents are caused by a driver missing an observation. This is the largest category of fatal errors. Physical factors, such as a permanent or temporary obstruction to a view, can cause this. Human factors also play a role, including distraction or inattention. A driver might also suffer from a faulty diagnosis. This means they misunderstood the actions of another road user. They might also experience an information failure or a communication failure with others.

Engineers also design junctions specifically for pedestrians and cyclists. Pedestrians use aids like crosswalks, walk lights, and overpasses. Some walk lights include audio signals to assist the visually impaired. For cyclists, protected intersections offer much higher levels of safety. These designs often use a corner refuge island and a setback crossing. In the Netherlands, one-way cycle paths are often at least 2.5 metres wide.

One advanced design is the Cycle-Optimised Signal (CYCLOPS) Junction used in Manchester, UK. This system places a circulatory cycle track around the edge of the junction. It includes pedestrian crossings on the inside to reduce conflicts. The traffic signals are timed to allow cyclists to make right turns easily. This design can also allow for a pedestrian scramble, which is a diagonal crossing. By separating different types of users, these systems make the entire network more efficient.