California electrified fences: a new concept in prison security.
In November 1993, the California Department of Corrections (DOC) activated an electrified fence model at Calipatria State Prison in Imperial County. Since then, another 23 have been installed, one is under construction, and more new prisons with electrified fences are being planned. Electrified fences have been installed at adult facilities for men and women throughout California's agricultural areas, foothills, deserts, coastal and urban areas, and a few at higher elevations.
At most of the facilities included in the California Statewide Electrified Fence Project, traditional perimeter guard towers are spaced at distances that allow correctional officers to use deadly force to prevent escapes. At newer facilities, as many as 10 towers (or 48.3 staff positions over three watches) can be deactivated. Using lethal fences greatly reduces the need for tower staff.
The electrified fence is installed between two parallel, chain-link perimeter security fences. It consists of 15 to 18 stainless-steel stranded wires, horizontally oriented and installed on insulators attached to metal fence posts. The wires are spaced at various intervals; they are close together (eight inches) at the lower portion of the fence and gradually increase in spacing toward the upper portion (13 inches). The top wire is one foot higher than the two perimeter security fences. A concrete-grade beam elevates the bottom wire to approximately 13 inches above the finish grade and prohibits anyone from crawling under the fence.
Circular, stainless-steel detection rings, attached to the lower electrified fence wires, trigger an alarm if the wires are spread vertically and come in contact with an adjacent ring/wire.
The electrified wires are charged with more than 5,000 volts and very low amperage many times the dosage normally considered lethal. Specially designed control cabinets step up the voltage from 480 volts. Sensor cabinets monitor current flow and loss of voltage, and detect when someone or something touches the fence. The electrified fence carries only an appreciable current flow (i.e., amperage) when an object contacts the wires; therefore, operation of the fence requires minimal electrical power consumption.
The electrified fence typically is divided into four to six separate zones for location monitoring and emergency response. Because the cost of the fence increases as the length of the perimeter and the number of zones increase, a facility with a perimeter of 7,000 feet typically would be divided into four electrified fence zones.
Graphic alarm annunciation panels are located in the continuously staffed sally port guard tower and the central control room. Panels display alarm status by zones and indicate high temperatures, open doors on control cabinets, and other operational conditions. Information is transmitted to outside patrol vehicles and watch commanders.
A computer system logs alarm and fence status information to generate various status and historical reports. The reports serve as valuable aids in forecasting maintenance, troubleshooting and tracking operating status. Reports can be printed out chronologically, by zone or by type of alarm.
California DOC's safety features for the electrified fence include:
* at least 10 feet of space between the electrified fence and the exterior perimeter security fence;
* security glazing panels to eliminate accidental contact at sally ports where the electrified fence terminates;
* interlock panels that de-energize power, ground the high voltage fence wires, and verify that the fence has been deactivated before maintenance or emergency response crews go between perimeter fences;
* high voltage test meters used for maintenance or emergency response personnel to provide an additional independent check that the fence has been deactivated prior to staff entry between perimeter fences;
* graphic warning signs on the inner and outer perimeter security fences in English and Spanish; and
* annual safety and operations training for security and maintenance personnel.
History of the Project
"The concept of the electrified fence was first originated in our technology transfer committee," says Kevin Carruth, deputy director of California DOC's Planning and Construction Division. "With the rapid increase in the inmate population, we needed to find additional cost-effective ways of building and operating prisons." Most medium security and all maximum security prisons in California's system have guard towers spaced at distances that allow correctional officers to survey the entire security perimeter and use deadly force, if necessary, to prevent escapes. Other prisons conduct surveillance from a combination of earthen perimeter berms and guard towers at prison entrances. California's DOC determined, and its Legislature agreed, that installing electrified fences could create substantial savings in annual staff costs.
"After the initial development of the concept, we turned to the private sector for design and construction," says Carruth. California's DOC contracted with an engineering firm to design the fence and a construction management firm to manage the construction process. The DOC and its program manager provided overall management of the project.
The following were the primary objectives in developing the Statewide Electrified Fence Project:
* Provide a physical and psychological deterrent.
* Reduce staffing costs by providing alternative perimeter security allowing the deactivation of most guard towers (except at vehicle and pedestrian sally ports) and berm surveillance positions.
* Maintain the same level of perimeter security as provided by the 24-hour staffing of guard towers to prevent inmate escapes and protect public safety.
* Maintain a cost-efficient system of perimeter security, both in terms of construction and life-cycle costs.
* Prevent accidental contact by staff, inmates and the public based on the location, design, construction and operation of electrified fences.
* Avoid, to the extent feasible, accidental and unintentional electrocution of wildlife.
* Standardize the electrified fence for new facilities based on a prototypical design, site adapted as needed to meet existing conditions.
One of the main concerns during design was security. Several important features were incorporated into the final design, including:
* The top electrified fence wire is one foot higher than the top of the perimeter fences. This makes bridging across the perimeter fences more difficult.
* Wire spacing is close enough to prevent an inmate from stepping or crawling between the wires without touching them.
* Devices will trigger an alarm if wires are spread.
* A lethal perimeter is maintained by using a lethal-only mode of operation.
* A concrete-grade beam beneath the entire length of the electrified fence makes crawling or tunneling under the fence more difficult.
* Alarms are transmitted by radio to a dedicated 24-hour roving patrol vehicle.
* The electrified fence should be lethal and should sound and display alarms.
Project Costs and Operational Savings
The construction cost of electrified fences varies depending on the perimeter length and site-specific conditions at each prison. The construction cost typically is within the range of $1 million to $2 million for an individual electrified fence of approximately 8,000 lineal feet. The average cost is approximately $1.5 million.
The operational cost savings of the electrified fence project result from the reduced staffing of the prison's guard towers and berm positions, minus the operations and maintenance costs of the fence and the additional roving patrol vehicle. Generally, the cost savings range between $400,000 and $2.1 million per year per prison, with an average operational cost savings of $1.38 million per year per prison.
Therefore, the cost of each fence is paid back within the first or second year. For the fences completed or now under construction, the California DOC expects a systemwide reduction of more than 750 positions for a savings of approximately $40 million per year.
Unanticipated Environmental Effects
When California first began to explore the concept of lethal electrified fences as a perimeter security alternative, there was no indication that the project would result in any adverse environmental impacts until the prototype at Calipatria State Prison. Birds, because they are mobile and tend to perch on manmade structures, often are accidentally electrocuted.
The possible "taking" (i.e., electrocution) of protected wildlife species is a primary concern. Protected species are those listed as rare, threatened or endangered under the California or Federal Endangered Species Act. Additionally, most native bird species are migratory and protected by the Federal Migratory Bird Treaty Act, which prohibits the taking of such birds.
When the DOC realized that wildlife were being electrocuted, it brought in environmental consultants to address the problem. With the advice and assistance of environmental consultants, the DOC is working diligently with the California Department of Fish and Game and the U.S. Fish and Wildlife Service to reduce the problem of accidental wildlife electrocution. California's DOC is studying and field-testing the feasibility of devices that would deter or exclude wildlife from the perimeter, and netting that encloses the portion of the fence most lethal to birds seems to be the most promising.
California's program has greatly reduced the need for tower staff, saving the state an average of $1.5 million a year per "electrified" prison. "The electrified fence clearly is meeting our goal of providing cost-effective perimeter security," Carruth says. "A final resolution to the environmental problem will make the program a complete success."
Gary Straughn is facility captain for the California Department of Corrections. Jack Richardson is project manager for Kitchell CEM. Allen Randall is principal electrical engineer for Boyle Engineering, Inc. Brian Hoffmann is senior wildlife biologist for Michael Brandman Associates.
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|Title Annotation:||In Search Of...Security; Annual Security Issue and Buyer's Guide July 1996|
|Author:||Hoffmann, Brian; Straughn, Gary; Richardson, Jack; Randall, Allen|
|Article Type:||Cover Story|
|Date:||Jul 1, 1996|
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