Upgrading Security - The Drinking Water - page 265

Because these barriers are not anchored into the roadway, they do not
require excavation or other related construction for installation, and they can
be assembled and made operational in a short period of time. The primary
shortcoming to this type of design is that these barriers may move if they
are hit by vehicles; therefore, it is important to carefully assess the placement
and anchoring of these types of barriers to ensure that they can withstand
the types of impacts that may be anticipated at that location.
Because the primary threat to active security barriers is that vehicles will
attempt to crash through them, their most important attributes are their size,
strength, and crash resistance. Other important features for an active secu-
rity barrier are the mechanisms by which the barrier is raised and lowered
to allow authorized vehicle entry, as well as such other factors as weather
resistance and safety features.
Alarms
An alarm system is a type of electronic monitoring system that is used to
detect and respond to specific types of events, such as unauthorized access
to an asset, or a possible fire. In water and wastewater systems, alarms are
also used to alert operators when process operating or monitoring conditions
go out of preset parameters (i.e., process alarms). These types of alarms are
primarily integrated with process monitoring and reporting systems (e.g.,
SCADA systems). Note that this discussion does not focus on alarm systems
that are not related to the processes of a utility.
Alarm systems can be integrated with fire detection systems, intrusion
detection systems, access control systems, or closed-circuit television (CCTV)
systems such that these systems automatically respond when the alarm is
triggered. A smoke detector alarm, for example, can be set up to automat-
ically notify the fire department when smoke is detected, or an intrusion
alarm can automatically trigger cameras to turn on in a remote location so
personnel can monitor that location.
An alarm system consists of sensors that detect different types of events; an
arming station that is used to turn the system on and off; a control panel that
receives information, processes it, and transmits the alarm; and an annun-
ciator, which generates a visual or audible response to the alarm. When a
sensor is tripped, it sends a signal to a control panel, which triggers a visual
or audible alarm or notifies a central monitoring station. A more complete
description of each of the components of an alarm system is provided below.
Detection devices (also called sensors ) are designed to detect a specific type
of event (such as smoke or intrusion). Depending on the type of event they
are designed to detect, sensors can be located inside or outside of the facil-
ity or other asset. When an event is detected, the sensors use some type of
communication method (such as wireless radio transmitters, conductors, or
cables) to send signals to the control panel to generate the alarm; for example,
a smoke detector sends a signal to a control panel when it detects smoke.