Battlements

A bollard is a short, well- anchored post that is used for mooring boats and ships. The following image from Google Street View shows a bollard at the Welland Canal.

The posts that are seen everywhere as barriers to errant vehicles, or to people who drink and drive, are also called bollards. My photo.

However I believe that this is a mistake, since the two are completely different things, and that these vehicle barriers should have their own name. 

In medieval castles the battlements were a parapet on a roof or tower with openings for archers to shoot at an approaching enemy. The following two images are from Google Street View. 

The battlements give archers a space to shoot arrows, while at the same time providing cover from enemy arrows. These vehicle barrier posts are spaced to achieve exactly the same purpose. They allow pedestrians, deliveries and, shopping carts to get through, but would block a vehicle. So why don't we call these posts "battlements"?

Battlements are often used to protect gas stations, where the vehicles are often pointed directly at the building. They may be brightly colored to make them more visible at night. These two images are from Google Street View.

The battlements that protect the gas pumps may be shaped like an inverted "U". Image from Google Street View.

Battlements are often seen at banks to protect the outside ATMs. First image from Google Street View, second is my photo.

Sometimes boulders are used as battlements. Image from Google Street View.

These battlements around Buffalo City Hall are in the form of spheres. They were put there without being anchored in the ground and it is their mass that provides the protective barrier. Image from Google Street View.

I definitely think that they should be called "battlements" because they serve exactly the same purpose as medieval battlements.