Personnel performing this type of rescue need to be physically fit as climbing a structural tower and performing a rescue are very physically demanding and will often cause the rescuer to become fatigued. You should note that we will not be discussing power transmission tower emergencies in this series as these types of rescues are conducted by trained line-men and out of our scope of expertise. If you are presented with a rescue that needs to be conducted on power transmission towers this should be done in conjunction with the local utility company to help eliminate any electrical hazards.
What type of work is being conducted on structural towers that may cause an emergency response in your district? Structural towers nationwide are being climbed and worked on more often than you think. If you have a structural tower in your response district you can be certain that it is being climbed a minimum of once a year and may be several times. The work being performed on these structural towers could be the repair of some failed structural components which could cause a high potential of an emergency response in itself. They may be rewiring some electrical or broadcast cables that have been damaged. They may be replacing the beacon bulb at the top of the structural tower which is required annually. They may also be conducting some routine maintenance or retrofitting the structural tower with new components. The work being performed on these towers annually is plentiful and we must be prepared to handle this type of emergency.
Fall Restraint System
Conduct a Hazard Assessment
The first phase of structural tower rescue is conducting a hazard assessment of your response district and to pre-plan these sites to determine your response capabilities. The majority of the time structural towers are fenced in and have the tower owner’s information plate posted. This plate is a good contact while pre-planning these sites to gather information from the owner on associated hazards and the tower’s use. Normally owned by one company, these towers can lease space to several other companies for radio or cell antenna use.
Commercial Wire Fall Restraint System
During your hazard assessment you concluded that you have several structural towers in your district. So now what? Well the first thing to do as mentioned above is conducting a pre-plan and determine your response capabilities. Ask yourself three questions.
- Do we have the trained personnel in our department to conduct this type of rescue?
- Do we have the equipment to conduct this type of rescue safely?
- If not, do we have a mutual aid company that can perform this type of rescue?
These questions must be answered before you as a department can determine what actions you must take when responding to an incident of this nature. We will discuss some specific equipment needed to perform this type of rescue in the next issue.
Structural Tower Awareness
Once you know what your response capabilities are it is imperative that personnel have a general understanding of structural towers. Structural towers can range in size from 85 feet to 1,500 feet. The majority of structural towers in the U.S. are less than 125 feet. Structural towers come in many different heights, shapes and configurations. The main construction material for these towers is metal. These towers can be held in place by guy lines or be self-supportive with the base of the tower bolted in a concrete slab. The two most common towers seen across the U.S. are lattice towers and monotube towers.
Monotube Tower with Step Bolts
Lattice towers are constructed with angle iron that acts as the main tower support that are bolted or riveted together. The angles in which this lattice is secured gives the structural tower its strength and support. The base of lattice towers can range from three to 60 feet. The climbing systems on lattice towers will be dependent on the size and height of the tower. Some lattice towers will be outfitted with a metal ladder system with a fall restraint wire while others may have a tubular rail fall restraint system. Both of these systems allow the worker to attach a commercial grab device which is trailed up with them as they climb the tower. The commercial grab device captures the worker if they fall eliminating injury or death. Some structural towers that are greater than 1,000 feet will be configured with a one-person elevator to assist workers performing maintenance at or near the top of the tower. Narrow lattice towers may not be equipped with a ladder system in which the rescuer’s only option may be to climb the outside lattice using a fall restraint system such as a double lanyard. We will talk more about the double lanyard fall restraint system in the next issue.
The second most common tower, the monotube tower, is gaining much popular demand within the industry. Monotube towers utilize a step bolt system as a means to climb this type of tower. These towers are virtually unclimbable to non-authorized personnel because of removable step fins, removable ladder sections or step shields which are anti-climbing devices. These towers are narrow and take up less ground space because of the narrow base. We are finding these more common in the urban environment where the cost of land is more expensive. The monotube tower poses a challenge to rescuers due to the lack of rescuer space on the tower to conduct the rescue and the lack of suitable anchor points. I have provided pictures of these two most common types of towers with some common ladder systems.
We as rescuers now need to know what on the tower poses a hazard to us. This information will be received during the tail gate meeting with the tower owner in which we will talk about in the next issue. What we need to understand as rescuers is it is not what we see that can harm us but what we can’t see that is the true hazard. We need to be aware of what type of radio frequencies are being transmitted and received from these towers. It is not always going to be known at the time of conducting the rescue operation. Radio frequencies can be compared to the wave of a microwave oven. If you place your body in front of a high frequency radio wave and interrupt its path of travel it can cook your body. The simplest way to prevent injury or death from high frequency radio waves without providing too much information to you is to keep your body and all equipment away from the front of all microwave dishes and collector horns. I have provided a picture of one of these microwave dishes. Other hazards the rescuer might be confronted with are electrical hazards that might need to be secured prior to the rescue operation commencing. Instability of the structural tower and the general height of the tower itself could be a hazard. All of these hazards should be weighted prior to the rescue operation commencing.
Pre-planning should incorporate elements of tower risk analysis. This analysis enables rescues to determine the amount of risk that is associated with the rescue. We will look at three risk analyses:
- No Risk
- Moderate Risk
- High Risk
All tower rescues involves some type of risk to the rescuer or the victim. No risk means “No Risk” to the rescuer in a situation in which an individual may have climbed a structural tower as a dare and the rescuers are able to talk the victim down by themselves. Moderate risk is anytime a rescue is required to climb a structural tower to conduct a rescue with no immediate secondary hazards. High risk involves the rescuer climbing and conducting a rescue on a structural tower that may have the presence of high frequency radio waves, electrical hazards, structural instability or a suicidal victim. Remember this. Structural tower rescue will always involve the rescuer climbing and putting themselves at risk unlike other high angle emergencies where you may be able to get to the top of the mountain by vehicle or to a high rise roof via an elevator to conduct the rescue.
In the first part of this series of articles I have focused on structural tower awareness to include construction characteristics, structural tower access and associated structural tower hazards. I have also provided some basic understanding of structural tower pre-planning and how important it is to visit these sites in your district and prepare yourself for a possible emergency response to this type of rescue.
Next issue we will be focusing on structural tower management to include tower related emergencies and medical considerations. We will also be discussing preparations for climbing and associated fall protection.