In the last installment of The Apparatus Architect (October 2003), we discussed the importance of planning and evaluation in the process of developing specifications for the purchase of a new ladder company apparatus. While we might possess the technical experience to develop specifications for a...
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Midship aerial devices generally provide for shorter overall travel height where station door clearance or other overhead obstructions are a concern. However, you must be careful to specify the appropriate overall vehicle height that meets your needs, without accepting a special low-profile model that may not provide for adequate compartmentation and ground ladder storage to meet your needs. Many departments, particularly those in the East, must operate from older fire stations that have a fixed door or beam clearance that would preclude them from specifying an aerial truck with a travel height over 11 feet.
It is poor policy to design fire apparatus to fit fire stations. Considering that the next aerial apparatus your department purchases will have to be in service for 25 to 30 years or more, it may be wise to hold off making that purchase if there is a chance to renovate your existing station or to build a new station to fit a modern-day aerial device. Your apparatus committee needs to make sure that whatever the maximum allowable travel height can be for your jurisdiction, that this number be clearly communicated in your specifications and that you fully understand what impact this has on the design and storage space within the body compartments.
We have probably all heard about some fire department that went to accept its new ladder truck from the manufacturer, only to find out that it did not fit the station or through some critical overpass in the community. Even more embarrassing is when you go to place all of your truck company hands tools and equipment on the new rig, only to find out that the compartments are filled up before you have found a home for everything that you want to carry.
Another consideration with midship-mounted aerial devices is that in most instances they are designed to reduce the overall travel height of the apparatus and this may limit the number of ground ladders that the vehicle can accommodate and how they are carried inside the apparatus body. Every manufacturer must provide the National Fire Protection Association (NFPA) required minimum ground ladders of 85 feet on a quint and 115 feet on a non-quint aerial apparatus. While this may meet the standard, this ground ladder complement may be inadequate to cover the buildings in your first-due area and significantly less than what your present ladder company apparatus carries. Make sure that the apparatus committee carefully reviews and considers what your requirements for ground ladders are when designing the new apparatus.
Photo by Tom Shand
Rear-mount aerial ladder units offer large body compartments without sacrificing fire pump, water tank and hosebed areas that are used on quint apparatus. Note the short ladder overhang in front of the cab on this Seagrave rear-mount ladder company apparatus operated by the Tenafly, NJ, Fire Department.
The banking height for ground ladders is different for solid-beam vs. truss-style ladders and this must be considered as well when determining the appropriate ground ladder complement for your new apparatus. Do not let the manufacturer’s representative sell you on “the truck is fully NFPA compliant” as being the seal of approval for anything. NFPA 1901 is only a minimum standard. If the new truck does not meet the needs of your fire department, then change, adapt or modify the design to make sure that it does. Manufacturers that are truly interested in your business will be more than happy to figure out, with the assistance of their engineering departments, how to configure the ground ladder arrangement and banking to meet your needs or to develop alternative solutions for problems that you may encounter.
Where fire station bay length and maneuverability is a concern, the rear-mounted turntable unit may be preferred for a number of reasons. The rear-mount aerial ladder offers a significantly shorter overall length when compared to a midship unit. In addition, the ladder overhang over the cab generally allows for a shorter turning radius when combined with improved steering geometry, which can be important when operating on narrow streets or in apartment complexes. Since rear-mount ladders generally have higher overall travel heights, there are fewer restrictions on compartment and ground ladder options.