The Rigs We Ride — Hazmat Apparatus Design

By Glenn Clapp CSP, EFO, CHMM, CFPS

As hazardous materials responders, we are well versed in certain topical areas such as air monitoring, personal protective equipment, product control, and many related others.  One area, however, that hazmat responders do not often delve into is the design of the apparatus we ride to and from hazmat calls; and just as importantly employ operationally at incidents. Since hazmat apparatus do not usually receive the amount of wear and tear over time as other “traditional” fire apparatus we may only see them replaced a few times in our hazmat careers and due to this frequency of replacement, we may have very few opportunities to design such an apparatus.  It, therefore, behooves us to discuss some of the elements of hazmat apparatus design due to the fact that our efficiency and effectiveness on the hazmat scene; and even our safety and well-being depend upon the development of a response vehicle tailored to our jurisdiction, team needs, and the hazards we face.  

The first step that we should take when we determine that our hazmat team either needs to upgrade to a new apparatus or purchase our initial piece of rolling stock is to perform a needs assessment. We should take into consideration the hazards that we face in our response territory, the equipment that we will be placed on the unit; and our response and on-scene operating procedures. The assessment will then allow us to develop the specifications for our apparatus to enable us to have the right “fit” for our needs. Our attention should then turn to the type of apparatus that will best suit our needs. One of the first questions that arise is in regard to the chassis upon which the apparatus is built, namely should we go with a commercial chassis or custom chassis. Commercial chassis are those that are manufactured by companies that produce truck chassis for many different types of applications. Commercial chassis can normally be purchased for less than a custom chassis (ideal for budget-conscious hazmat teams or those departments starting a team). Custom chassis are those manufactured by traditional fire apparatus manufacturers to meet the specifications of the customer and although they are usually more expensive than commercial chassis the customer specifies all of the details of the chassis build and oftentimes such custom chassis provides the customer, with safety features specific to purpose-built emergency response vehicles. In any event, as the end customer, your team should ensure that the engine powering the apparatus meets the horsepower and torque requirements for the geography and topography of your response district. Selecting the most appropriate rear axle ratio and transmission specifics is also imperative with respect to the nature of our response area (e.g., is our area flat with wide-open highway responses, or do we have a hilly topography with roads that rarely travel in a straight line?).  

The next major decision in our journey of hazmat apparatus design is that of whether our needs dictate that we utilize a straight chassis or tractor-trailer chassis. Each of the choices has its own benefits and drawbacks. Straight truck chassis are mechanically simpler than tractor-trailer chassis and do not ordinarily require special licensing or driver training beyond that for similar fire apparatus.  Tractor-trailer apparatus normally have more equipment storage area than straight trucks and are very maneuverable for their overall length, however, they require detailed driver training and special licensing (in North Carolina a non-CDL Class A License). Another detail driving the selection of your chassis is how your team responds to hazmat incidents, namely the use of a centralized or decentralized response model. A centralized response model consists of the hazmat team responding out of one station on an oftentimes larger apparatus (often accompanied by technician-level companies from other stations) whereas a decentralized model consists of multiple hazmat response apparatus responding from multiple stations.  A decentralized model of response allows the use of smaller apparatus overall or even a primary hazmat response unit accompanied by smaller “satellite” units or smaller trucks towing trailers designed for various functions, resulting in overall savings to the team and department. If your team decides to select a straight truck for your hazmat unit a secondary decision arises. Hazmat units built on straight truck chassis are often modeled on fire service rescue apparatus in that they can be of the walk-in body type that can house additional personnel in the body area and allow for inside access to storage or they can be of the walk-around body type that offers more overall storage capacity.  

The next decision area is usually that of the accessories needed on the apparatus. Our hazmat team may need lighting, compressed air, and electrical power out in the field which dictates the need for an onboard generator and/or air compressor.  The use of modern LED lighting can also greatly reduce the size of the generator needed.  This portion of the discussion in turn leads us to the need for dedicated areas and equipment for auxiliary functions including a research area, weather data-gathering equipment, drone operations area, and personnel shelter areas for inclement weather each with their respective infrastructure requirements. Most hazmat units now include a dedicated research area that allows the Research Group to determine the product or products involved, their inherent hazards, and the personal protective equipment that is appropriate for the hazards encountered. Research Group personnel need to have a climate-controlled environment with sufficient lighting and supply of electrical power in which to perform their work. Although we normally use electronic sources for research in modern-day hazmat response, we also cannot forget the need for hard copy back-ups in the form of research books and the storage requirements that result.  As Research Group personnel have one of the most demanding roles on the initial hazmat scene with the Incident Commander, Hazmat Branch Director, et al. wanting to know what the team is dealing with in the initial stages of an incident, one of the most effective pieces of equipment in the research area is a lock on the door that secures access to the area and lets the personnel attend to their duties (although I probably should not make that statement out loud).  

Another needed provision on modern hazmat apparatus is for weather data gathering.  Hazmat teams can perform very accurate plume modeling in the field; however, that accuracy is dependent on the input of data that is correct for the incident scene. If we call for a weather report from communications or even the National Weather Service, the reporting location may be many miles away from our incident scene with vastly different weather conditions.  An onsite weather station allows us to obtain the real-time weather conditions at our incident scene and hence increase the accuracy of our plume modeling.  As the use of drones for reconnaissance and intelligence gathering at hazmat scenes has dramatically increased, we should not forget the need for drone storage, charging, and launch/recovery equipment storage area if your hazmat team has or wishes to develop that capability.  In addition, response personnel needs a sheltered area in which to dress out prior to entry into the hot zone and to rehabilitate in after leaving the decontamination area. At a minimum, we should provide an awning and seating for those personnel or even ideally provide a storage area for a tent or other suitable shelter that could also include heating and cooling capabilities.  

In summation, if we put in our due diligence through conducting a thorough needs assessment of both of our jurisdiction and our departmental/hazmat team needs and then carefully develop the type of hazmat apparatus matched to those needs and the specifications thereof, we can realize huge benefits in our efficiency and capabilities at the hazmat incident scene; and our safety going to the scene, at the scene, and returning home to the station as we all look forward to doing after a successful hazmat incident.  Doing so can also allow us to be stewards of our taxpayers’ money in maximizing our capabilities while keeping expenditures to a manageable level.  As always, stay safe out there and be sure to visit the North Carolina Association of Hazardous Materials Responders website at

Glenn Clapp is a past president of the North Carolina Association of Hazardous Materials Responders and has over 24 years of fire service and emergency management experience. He is currently an Improvement Specialist with the Industry Expansion Solutions Division of North Carolina State University and is a volunteer firefighter with the Fairview Fire Department. He is also a Technician-Level Hazmat Instructor, an Executive Fire Officer, a Certified Hazardous Materials Manager and a Certified Fire Protection Specialist. 

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