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Fire Truck Compartment Dimensions

By Bill Adams

Many fire apparatus manufacturers have single-sheet pieces of advertising literature with a rig’s photo on the front and hard-to-read blueprints on the back showing four or five views of the apparatus. Look very closely because the prints may be misleading, although I doubt purposefully deceitful. Case in point: one particular side view showed a 130-inch-long pumper body with high side compartments featuring a 30-inch-wide compartment ahead of the rear wheels, a 60-inch-wide compartment over the wheel well, and a 40-inch-wide compartment behind the rear wheels. Don’t be fooled by the numerical measurements.  

This print had an equally hard-to-read legend titled “COMPARTMENT DIMENSIONS.” Under an “INSIDE DIMENSIONS” subheading, it showed the compartment ahead of the wheels being 26 inches wide; the one over the wheel well at 60 inches wide (same as the print), and the one behind the rear wheels at 36 inches wide. Because of the various methods of fabrication used throughout the fire apparatus industry, it is understandable that door framing and body structural members may cut down on the interior dimensions. Regardless of the construction method and the type of materials used, manufacturers should, at the least, tell the customers actually how much room is really available.


It gets more confusing. Some prints also list “CLEAR DOOR OPENINGS.” The compartment ahead of the rear wheels is 21½ inches wide; the one over the wheel well is 53¾ inches wide, and the one behind the rear wheels is 31½ inches wide. Most manufacturers calculate clear door openings between the structural door framing (the door jambs). Blueprints and technical specifications seldom, if ever, indicate if clear door openings include door pan or door hardware interference. Actual usable clear door openings could be reduced by another 1½ to four inches depending upon whether roll-up or hinged doors are used, the number of doors per compartment, and the type of hardware provided. 

Complicating matters, most blueprints have a disclaimer stating that the print is for reference only and if there’s any variation between the print and the specifications, the specifications will prevail. An actual usable compartment width could be 25 percent LESS than what a blue print shows. Does it matter? I think so. A purchaser may erroneously believe a 34-inch-wide smoke ejector will fit into the 40-inch-wide compartment behind the rear wheels. Purchasers are urged to use diligence when writing compartment specifications—especially if storing unique or odd-size pieces of equipment and moreso if the intention is to maximize storage space.  

There are a multitude of ways to describe compartment dimensions in purchasing specifications. One is to be exact by stating the compartment “shall be” the listed dimensions. “Shall be” compartments are usually considered proprietary. Proposals without those exact measurements should take an exception. Another method is to describe a minimum by stating the compartment shall be “no less than” the listed dimensions. Bidders with smaller dimensions should take exception. Those with larger ones do not. Be careful if compartments are specified as “approximately” the listed dimensions. Being approximate is in the eyes of the beholder. There is no correct answer. Any compartment dimension larger or smaller may be construed as “approximate.” If the intention is to ensure specific equipment will fit in a specific compartment,  consider writing a performance specification. Be as specific as possible. Use plain language. Include a diagram. It’s legal to do so.

Apparatus purchasing committee members from several fire departments were asked why they included exact compartment dimensions in their technical purchasing specifications. Responses ranged from “Gee, I don’t know why” to “I never thought about it” to “That’s what was recommended by the vendor who helped us write the specs.” Only the brave or honest or narcissistic said it was to specifically eliminate all potential bidders except their preferred vendor.

Vendors can be placed in a precarious position when discussing compartment dimensions. A preferred vendor will not complain. Vendors whose dimensions have not been used or whose compartments don’t meet the specified dimensions obviously will. How loud they complain will dictate the degree the purchasing committee has to defend its decisions to the authority having jurisdiction—the entity that signs the check. In regulated bidding environments with multiple competitive and aggressive bidders, purchasers may be challenged publicly. Specifying compartment dimensions that are proprietary to a particular vendor can invite critique. But if a spec writer’s intention is to write the specs around one manufacturer, so be it. Live with it—and its possible consequences.  

Use caution. No fire chief wants to be confronted in a public forum: Why did you specify those exact compartment dimensions? Be prepared. The mayor or one of his minions who “signs the check” might be asking the question.

BILL ADAMS is a member of the Fire Apparatus & Emergency Equipment editorial advisory board, a former fire apparatus salesman, and a past chief of the East Rochester (NY) Fire Department. He has 50 years of experience in the volunteer fire service.


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