by Judy K. Bell, CEM
Disaster Survival Planning Network
PROCEEDINGS: 1993 NATIONAL EARTHQUAKE CONFERENCE; Earthquake Hazard Reduction in the Central and Eastern United States: A Time for Examination and Action. May 2-5, 1993, Volume 1, pp. 339-348
Experience has taught us after every major earthquake that the public telephone network will be congested. Both the increased volumes caused by people attempting to reach their loved ones and controls which the local telephone companies and interexchange carriers must activate to protect the network will decrease everyone’s chances of getting their calls through.
Every organization, whether it is a public agency, business, volunteer organization, or educational institution, must identify in advance who needs to communicate with whom. They must develop alternate forms of communicating other than the normal telephone network.
This paper explores how to determine who needs to set up special communications, and how each organization can determine whether the alternatives they are planning to use will be affected by congestion on the public telephone network. It will identify both strengths and weaknesses of each type of communications.
The telephone network, just like our freeway systems, is constructed based on projected normal usage. Actual data is collected daily to determine the busiest hour of the day, and from that information the engineers design the capacity of the switches and telephone network. Generally, customer calling patterns indicate that no more than 10% of the customers in a local area will use their telephone at the same time.
When disaster strikes, regardless of media warnings to use the telephone only if it is an emergency, many people immediately pick it up to call their loved ones. The calling volumes escalate exponentially, causing the switching equipment and trunking facilities to quickly become overloaded. In today’s electronic environment, the telephone switches are giant computers, which react to overloaded conditions by placing customer calling requests in queues. As more and more customers try to use their telephones, the switches eliminate all peripheral activities in an attempt to process as many calls as possible.
Following the October 1, 1987 Whittier, California, earthquake, call volumes exceeded all previous loads on the telephone network. During the first two hours, call volumes ranged as high as five times the normal business day load. Mothers’ Day is traditionally the highest calling day of the year, yet calls that day surpassed the highest Mothers’ Day loads previously recorded. Similar congestion occurred following the Loma Prieta earthquake two years later.
Local telephone companies and the interexchange carriers immediately place commands in the network to open up the affected area so that people within the disaster region can call out. By blocking incoming calls and using those same routes to allow people within the area to complete outgoing calls, congestion levels can be reduced more quickly. Studies performed by the Bell System prior to divestiture indicated that for every call that can be completed from within the affected area, it would prevent ten more calls from outside the area from attempting to call in.
Other factors can also inadvertently cause congestion in the telephone network. An amateur radio operator in the San Fernando Valley of California was one of the first people to get through to Northern California in the first few minutes following the Whittier earthquake. He called a radio station in Northern California and informed them that a major earthquake had just occurred in the San Fernando Valley. This was the site of the devastating 1971 earthquake. The result was that everyone who had friends or loved ones in that area of Los Angeles attempted to call as well. The actual epicenter was centered more than 35 miles from that area, but because this incorrect information was broadcast, the telephone network was impacted in both areas. This additional congestion lasted for at least four hours following the event, as people continually made call attempts to reassure themselves that their loved ones were not affected.
Another phenomenon that is unique to earthquakes is aftershocks. Even those who heed the public warnings to remain off the telephones initially soon become conditioned to immediately call following every aftershock. Telephone network congestion can continue to peak for days and weeks following an earthquake depending on the number of large aftershocks.
In earthquake-prone areas, the telephone companies protect their equipment from damage by installing overhead bracing as well as bolting the equipment to the floor. They install both batteries and back-up generators to guarantee uninterrupted power sources. Manufacturers are required to build the equipment to withstand an 8.0 magnitude earthquake, which is tested on shaker tables. These preventative measures have proven extremely effective in reducing actual damage to the network. Following the Loma Prieta earthquake, not a single central office was lost due to damaged equipment. Yet even without physical damage, the network becomes undependable due to the elements of congestion mentioned above.
EXPLORING THE ALTERNATIVES
It is important to understand what alternatives can be used, and how to best use them. The most important element of using alternatives is identifying in advance what will be available. Many people do not understand how the different types of communications are affected by congestion on the public network, which can cause them to fail to use these resources, or pick the wrong ones. This section will explore all forms of communications that are generally thought to be alternatives, and will discuss the strengths and weaknesses of each.
This service is used primarily for police, fire, and other emergency agencies. However, it is not an alternative to the public telephone network. Essential service is a designation of the telephone user’s line equipment in the local central office that provides the caller dial tone in advance of others. Once the person placing the call receives dial tone, they are competing with all other callers to complete their call over the public telephone network. In a regional disaster, this service will be directly affected by the amount of congestion in the network.
Although it is not an alternative to the telephone network, it does provide a better chance of gaining access to the network, and should be considered in your planning. Even though congestion will occur, many calls will complete.
Public telephones are also designated as essential service, and as a result they too receive priority dial tone. If a business has public telephones on its premises in addition to a PBX, and the PBX fails after the disaster, chances are that the public phones will still be functioning. They may become the only link to the outside world to report emergency conditions. It is important to locate these phones in advance, and post their numbers in a visible location so that they can be used for both incoming and outgoing calls at the time of a disaster. Remember, though, that they may be affected by congestion on the telephone network.
After the Whittier earthquake, long lines of employees formed at telephone booths as they one-by-one called home to check on their loved ones. They were evacuated from their buildings, so this was the only way they could reach them.
Foreign Exchange Lines
Some organizations may use foreign exchange lines in their day-to-day business. Depending on what kind of foreign exchange service it is, that line may actually be drawing dial tone from a remote central office. If the remote office is outside the disaster area, this line may provide a way to complete and receive calls because it is not in the affected area. Many times this alternative is cost-prohibitive, so it should be incorporated in the planning only if it can be used for other purposes as well.
The telephone companies use this alternative in their Emergency Operations Centers, which provides alternate access to the public network. Notice it is still using the public network, just originating from a different geography.
Customer Premises Equipment
Many organizations have purchased PBX or other sophisticated telephone equipment which has been installed at the location. Just as the telephone companies secure their equipment and provide additional power sources, so too must each organization. Back-up power for telecommunications clearly was the most vulnerable element in past earthquakes.
Not as well-known is the factor that many of the sophisticated telephone instruments in use today rely on local power to operate. Any telephone that requires an electrical outlet to operate its features in addition to the telephone outlet will not work if electricity is affected, and that electrical outlet is not on an uninterrupted power supply. Some businesses retain old telephone sets that they can quickly plug in at the time of a disaster. Again, this is not an alternative to the public telephone network, but it will provide access if nothing else is working at that location. This is particularly helpful if the disaster is a single site event, like a fire or flood, rather than regional.
Private Lines (commonly referred to as P-Lines)
P-lines are an extremely effective way to communicate from one specific location to another. They are non-switched lines that extend from one particular telephone to another. Their use is most cost-effective on single site plants where one person needs to speak directly to another. P-lines appear as a button on a telephone instrument, and when pressed automatically ring the other end.
Organizations which are planning to activate an emergency operations center should consider this alternative for those people who will need to speak extensively with their staff, who may be located elsewhere. It is a private line, totally separate from the public network. It is better than radio communications, because only the two people can talk over it, and the only way it might not function is if there is a physical break in the line between the two locations, which is most unlikely.
This is a group of private circuits which function similar to the P-line, only there can be more than two locations tied together. These circuits have their own dedicated paths, so they do not use the telephone network. Some organizations install the circuits with speakers mounted in the ceiling. This allows everyone to hear the conversation that is transpiring while they continue to do their own work. Ring-down circuits provide instant access to key locations, which can determine the extent of damage instantly without attempting to communicate through the telephone network.
This type of circuit is used in the telephone companies typically in Network Management Centers and other key locations. Circuits can be installed in both local and interexchange company centers to provide immediate knowledge of the situation and to expedite the decision-making process of what actions to take to preserve the telephone network. Ring-down circuits are used in a variety of ways in the public sector as well.
Fax machines are literally everywhere these days. Faxes come in two varieties. Either they use a regular dial tone line, or they are provided on a private line from one location to another. Both types are worth considering when planning alternate communications. Faxes are an excellent way to pass damage information. If planned ahead, the information can be filled out on a predesigned form, with instructions to send the fax within a designated time after the event. Update intervals can even be specified, eliminating the need for any voice communications.
The second major advantage of using this form of communications is that it provides a written record of the information gathered, which may be helpful documentation for insurance and reimbursement needs afterwards. Further, written information will be more accurate, with less danger of valuable facts being lost in the translation. Fax transmissions are much quicker than verbal communications, which lessens the congestion, as well as frees up the people who would have had to pass the information verbally. If the datafax is provided on a private line, it is not subject to network congestion.
Cellular phones proved to be an excellent form of communications following both the Whittier and Loma Prieta earthquakes. However, in Newcastle, Australia, following the December 28, 1989 earthquake, cellular was as congested as the regular network. Cellular is a separate network, however, it too can become congested. Like the public network, it is designed for a certain level of capacity. As technology advances, the capability of the cellular network to expand to accommodate the demand is continuing to increase.
It is important to distinguish the type of calls that are placed over the cellular network. Calls from one cellular unit to another within the cellular company’s geography will exclusively use that network. However, if a cellular user attempts to call a landline, such as their home or office, the call will travel through the public telephone network to complete. Once again, those calls can be affected by congestion. This example emphasizes the reason why planners need to carefully evaluate how they will be using their alternative communications. In this instance, if the intent is to contact people who are on the public telephone network, they may not succeed.
Many public and private organizations are planning to use their radio frequencies for critical communications. Radios are clearly an alternative to the public network, but their use should be planned carefully. I am reminded of the Oakland Hills fire, where each fire department that responded had its own frequency. Careful planning is necessary to eliminate confusion and ensure that the right people will be able to talk to each other.
Some businesses use radio frequencies daily. Many times they assume that will be their primary back-up at the time of a disaster. However, when organizations identify in advance who needs to talk to whom, they will find that there are far too many people who need to convey critical information who will be relying on only one or two radio frequencies. In fact, radios can be rendered useless in disasters if proper planning has not taken place. If company officers are planning to use this alternative, chances are they will preempt all others from their use. It is best to identify who will be authorized to use which channels, and to incorporate their use into drills and exercises to make sure they will serve everyone’s needs adequately.
In every major earthquake, the amateur radio operators have been the most effective at relaying damage conditions. They should be integrally involved in the planning process, and used wherever possible in the early hours. The public sector has tapped this resource through RACES, which is an organization of amateur radio volunteers who work with local agencies to perform critical communications functions following a disaster.
Some businesses are encouraging their employees to become amateur radio operators, and plan to use them as the major link between families and employees if normal communications are affected. This is a very important function if a business requires some people to remain on the job, or if normal transportation routes are blocked and employees are forced to remain at work.
A variety of innovative plans have been developed. If a business has multiple work locations, they designate two or three of them as key assembly points. When a disaster strikes, amateur radio operators are assigned to report to these sites. If the disaster occurs during work hours, information about injured employees or those who must remain on the job is relayed to the site closest to the employee’s home, where local operators can then contact the family. If it happens out-of-hours, employees report to the key location closest to their home on their next scheduled shift, and are provided their work assignments from there.
Many companies have purchased services using satellite, which bypasses the local telephone network. It is important to identify what types of service transit these types of facilities, and build a plan that will use these circuits at the time of a disaster. Determining ahead of time who needs to talk to whom can quickly identify whether this is a logical resource to build into plans.
Most organizations use satellite communications to transport data or voice communications between two or more major locations. This is a ready-made alternative to pass damage and injury information in the initial hours. This is particularly effective if key decision-makers are remote from the site, and by using this link they can be informed quickly of the status to determine how they will conduct business.
Microwave communications are another completely separate alternative to the network. It is important if they are going to be used as an alternative that planners check how many other users are on their frequencies. They, too, can become congested, especially in large cities. Knowledge of antenna and transmitter locations is also important to evaluate how they may be affected at the time of a disaster.
Most large organizations transport data using private non-switched facilities. However, planners overlook the potential to turn these transport links into communications paths after a disaster. Evaluate which terminals can transmit information to which locations, and use this resource to perform damage assessment in the early hours. It can also become a two-way means to transmit restoration priorities. Even though the link may be via data rather than voice, just like the Datafax, this can be a ready means of communicating.
Some businesses are planning to have their employees dial up into their systems from home if a disaster occurs out-of-hours, to receive instructions and transmit critical information. This combination may be using the telephone network from employees’ homes to the main computer, so be aware that there may be congestion on that element.
Organizations which require extensive data capacity are evaluating where their vulnerabilities are in their networks, and over time are building in protections to preserve their data networks. Use of fiber rings to provide alternate routing, diversifying of facilities routes, obtaining fiber from more than one central office, and terminating cables on more than one distributing frame are all sound preventative measures to ensure your own network will continue to function.
HOW TO MAKE YOUR PLANS WORK
It is easy to see that there are many different forms of communication to evaluate. The most common missing ingredient in communications plans is identifying who needs to talk to whom. Physical drawings of where key people are expected to be are important to begin to see the overall communications picture.
In the early stages following a disaster, Emergency Response Teams and Site Inspection Teams will be frantically working while emergency centers are being activated. At the same time, key decision-makers will soon want to receive reports to begin to make decisions about what to do. Employees will be eager to reach loved ones, and everyone will need to know how the community has been affected. All of these needs must be addressed in the planning stages. If they are not, one or more of these users will try to establish communications links using whatever is available, possibly hampering other efforts.
Gather all of the key players from each interest group together, and identify what functions they will need to perform, and what kind of communications they require to perform these functions. Once that is established, it is a relatively easy task to survey existing communications, identifying which is best suited to serve the users’ needs. When organizations follow this process, they are pleasantly surprised to find that they already have plenty of communications alternatives, and may not need to spend exorbitant dollars for additional equipment.
Document these plans so that everyone will know who will use what. List all of the critical communications circuits, identifying where they are located, and who is to use them. Anticipate that everyone who knows the plan will not be available, so all information must be clear and easy to follow. Then test the plans to see if they will work. The time to find out whether everyone’s communications needs have been met is not during an actual disaster! It is only through careful planning and testing that organizations will have truly successful communications paths.