A traffic barrier is used to block traffic in an intermediary between traffic going different ways. Traffic barriers can be plastic or concrete and the plastic ones are usually filled with sand or water. There are many different specs when it comes to traffic barriers, so make sure you find out what is required for the job.
A traffic barrier is not the same as a traffic barricade, or a type III barricade. Traffic barricades are usually used on local roads, instead of highways like the traffic barrier. A traffic barricade is also not as heavy duty.