Usually when traffic cones are in the street it's meant to indicate that you're not supposed to drive in the area with the cones. There are some cases where cones are left out by accident though.
Ice cream cones, mathematical cones, frustums, traffic cones, pine cones...
traffic pylons, road cones, highway cones, safety cones, construction cones or (colloquially) witches' hats or safety wizards.
Traffic cones can be purchased at building stores (such as Home Depot) and larger sporting goods stores (such as Dicks). Walmart also carries these cones.
Traffic cones are orange because it makes them stick out more, making them easier to notice.
Traffic Cones - 2001 was released on: USA: 3 October 2001 (Los Angeles, California)
traffic pylons, road cones, highway cones, safety cones, construction cones or (colloquially) witches' hats or safety wizards.
Charles D. Scanlon invented the traffic cone in 1940. His invention was granted a patent in 1943. Scanlon got the idea while working for the Street Painting Department of the City Los Angeles.
Traffic Cones. Jersey Barriers. Traffic Barrels. Delineators. Frame Barriers.
If you mean setting up cones and signs, they must follow the Manual Uniform of Traffic Control Devices.
This is for stability.
If your talking traffic cones then it depends on the road, traffic, the speed of the traffic, the construction being performed and most of all on the person (making a low wage) pulling them off a truck or trailer and placing them...
Traffic cones are available in quite a few places. Staples has them, and online has the trafficsafetystore.com that may be worth a look. As always, Amazon can also be of assistance.