What's the purpose of the warning against entering the construction site?

Signs and signs during expressway construction are mainly divided into warning, prohibition, indication and indication. Among them, warning signs mainly play a warning role, such as paying attention to falling and getting an electric shock; The prohibition sign has a clear restrictive effect. Such as no access, no entry, etc. ; Indicating signs are used for guiding and prompting, such as indicating the route; Command signs are reminders, such as wearing a helmet.