A 3-way junction is a type of road junction with three arms. A Y junction (or Y intersection) generally has 3 arms of equal size. A T junction (or T intersection) also has 3 arms, but one of the arms is generally a minor road connecting to larger road.

Some T junctions are controlled by traffic lights, but others rely upon drivers to obey right-of-way rules. For example, a vehicle travelling on the major roads of the "T" typically has right-of-way, meaning that the vehicle approaching the "major" road must allow it to pass before joining the flow of traffic.

An experiment was done in Illinois

Illinois

Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

, United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 to allow going straight on red (like a right turn on red

Right turn on red

Right turn on red, or simply right on red, is a principle of law permitting vehicles at a traffic light showing a red signal to turn right when the way is clear, in a country with right-hand traffic...

) when approaching a T junction on the main road, with the intersecting road on the left. It was a failure. However, at some T junctions where the main road includes at least two lanes on the side away from the intersecting road, the farthest (rightmost, in areas where traffic drives to the right) lane is given the right of way to proceed straight through the intersection at all times, denoted by a "green arrow" signal if a traffic light is installed at the intersection. In such cases, often that lane is also specially delimited with pavement markings or other lane separation devices, to keep left-turning traffic on the intersecting road from colliding with traffic proceeding through the intersection on the main road. There are now safer variations of this, called Continuous T-intersections, that have a left-exit off of the main road to completely separate those going straight, which allows for a traffic signal on only one side of the road.

In the People's Republic of China, going straight on red when approaching a T junction on the main road with the intersecting road on the left was permitted until outlawed by the Road Traffic Safety Law of the People's Republic of China

Road Traffic Safety Law of the People's Republic of China

The Road Traffic Safety Law of the People's Republic of China is a law which was passed by the National People's Congress of the People's Republic of China on October 28, 2003, promulgated by Decree No...

 effective on 1 May 2004.

In Taiwan administered by the Republic of China

Republic of China

The Republic of China , commonly known as Taiwan , is a unitary sovereign state located in East Asia. Originally based in mainland China, the Republic of China currently governs the island of Taiwan , which forms over 99% of its current territory, as well as Penghu, Kinmen, Matsu and other minor...

, when at least two vehicles reach a T intersection without a working traffic light

Traffic light

Traffic lights, which may also be known as stoplights, traffic lamps, traffic signals, signal lights, robots or semaphore, are signalling devices positioned at road intersections, pedestrian crossings and other locations to control competing flows of traffic...

, the vehicle on the side road is to yield to any other vehicle straight on the main road. If two vehicles want to turn left, the vehicle on the left is to yield.