One way streets

 ONE WAY STREETS

A one-way street is a street either facilitating only one-way traffic, or designed to direct vehicles to move in one direction. One-way streets typically result in higher traffic flow as drivers may avoid encountering oncoming traffic or turns through oncoming traffic. One-way streets are common in city areas. They can be recognized from the signs and markings on the road. Broken white lines separate traffic lanes on one-way streets. Yellow markings are not seen on a one-way street. It is not illegal to reverse into a main road but it is not advisable 

Advantages: 

• increased capacity
• reduced intersection
• conflicts for pedestrians and vehicles
• reduced collisions.
  

Disadvantages:

• longer travel, 
• difficult orientation for out-of-towners, 
• potential for excess speeds
  

Some of the reasons one-way traffic is essential:

• The street is too narrow for movement in both directions and the road users unable to coordinate easily.
• Prevent drivers from cutting through residential streets to bypass traffic lights or other requirements
• to stop (a so-called "rat run")
  

One-way streets eliminate tough left turns through oncoming traffic. Flow is high on one-way streets because there's little reason for cars to slow down.

One-way operation permits much better traffic signal progression for smoother traffic flow. This results in traffic moving at regulated speeds with less stop-and-go driving.
 

This makes it much safer and faster for cross street traffic, bicycles, and pedestrians to cross major streets.