> For the complete documentation index, see [llms.txt](https://www.oulan.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.oulan.com/2020/03/04.md).

# 04

在路边安装栅栏有两个作用。可以有更高的速度，可以限制速度。

![](https://385430918-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M8iFCzaIpXf8zXqpE6I%2Fuploads%2FaZ4UHZPdWqTGwh3nkh99%2F29621651279762_.pic.jpg?alt=media\&token=2f91368f-7854-4c64-a148-829eb45e09fa)