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Apparatus Purchasing: Custom Cabs Part 2, the Safety Standards

Issue 3 and Volume 22.

By Bill Adams

Apparatus manufacturers (OEMs) that build their own custom cabs and chassis claim their products meet and often exceed the safety standards referenced in National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus (2016 ed.), and in particular the requirements of Section 14.3, Driving Compartment.

It is important to note that the OEMs’ assertions of compliance are to criteria established by entities outside of the fire service that are addressing the crashworthiness of cabs in the commercial trucking industry. They were adopted by NFPA 1901 in 2009. What are these standards? Who created them? Do they affect the specification writing process?

NFPA 1901

NFPA 1901 (2016 ed.) references more than 80 publications from 18 organizations. Sentence 2.1 states, “The documents or portions thereof listed in this chapter are referenced within this standard and shall be considered part of the requirements of this document.” They are not subject to negotiation, debate, or choice by purchasers and manufacturers when specifying NFPA 1901-compliant apparatus. Most purchasers pay little attention to referenced publications, accepting them as part of the system.

Publications with a “J” designation are published by the Society of Automotive Engineers (SAE), a professional group founded in 1905. From its Web site, “SAE standards are internationally recognized for their role in helping ensure the safety, quality, and effectiveness of products and services across the mobility engineering industry.” Two SAE J standards, along with a related United Nations (U.N.) document, are referenced in NFPA 1901 sentence 14.3.2: “Cabs on apparatus with a GVWR greater than 26,000 lb (11,800 kg) shall meet the requirements of one of the following sets of standards: SAE J2420, COE Frontal Strength Evaluation – Dynamic Loading Heavy Trucks; SAE J2422, Cab Roof Strength Evaluation – Quasi-Static Loading Heavy Trucks; and ECE Regulation number 29, Uniform Provisions Concerning the Approval of Vehicles with Regard to the Protection of the Occupants of the Cab of a Commercial Vehicle.” Keep in mind that the J2422, J2420, and ECE 29 criteria are not job-specific to the American fire service and its custom fire apparatus cabs. Most political subdivisions and federal and state governmental entities consider fire apparatus commercial vehicles that must comply with applicable rules and regulations. Formal exemptions are few.

1 A custom cab being subjected to a “dynamic preload that simulates the side loading on the upper cab” as a vehicle rolls past 90 degrees. This is the first part of a two-part test to determine the crashworthiness and survivability of occupants in a 180-degree rollover.
1 A custom cab being subjected to a “dynamic preload that simulates the side loading on the upper cab” as a vehicle rolls past 90 degrees. This is the first part of a two-part test to determine the crashworthiness and survivability of occupants in a 180-degree rollover.

Contrary to the belief of some firefighters and purchasers, NFPA standards are not secretly developed in a smoke-filled back room of a Boston office building by owners of fire truck factories seeking to increase profits. There’s an established method for the public to make comments, changes, and additions to any NFPA standard, and there’s a description of the professional affiliation of each technical committee member. They’re included in each standard. The NFPA standards process, a topic for later discussion, is not being debated.

J2422, J2420, and ECE 29 are addressed because they directly affect the safety of firefighters riding in fire apparatus cabs. Spec writers ought to know what they’re specifying – albeit in an abbreviated manner. And, firefighters should educate themselves on their fire truck – their primary tool. The NFPA 1901 Technical Committee on Fire Department Apparatus did not create the criteria for fire apparatus crashworthiness. It wasn’t plucked out of the air in that back room in Boston. It was adopted by referencing existing domestic and foreign safety standards established for the commercial trucking industry and not specifically for fire trucks. Although it appears research into “crashworthiness” started right after World War II, NFPA 1901 did not formally adopt the aforementioned safety standards until the 2009 revision.

The Real World

I, and I’m sure most others, do not expect apparatus purchasing committee (APC) members to be intimately familiar with each and every referenced publication in NFPA 1901. It is debatable whether vendors are or should be.

However, if either a buyer’s or seller’s specification explicitly refers to a third-party publication, it is reasonable to expect those spec writers should know what they’re talking about. It is especially so when the specification’s requirements exceed those of the referenced third-party publication.

As an example, one OEM’s published literature stated that its custom cab exceeds the minimum requirements of J2420 by a factor of two. Another said the requirements of J2422 were exceeded by a factor of five. Another said its cab roof could withstand a roof crush test several times more than what is required by ECE 29. When those figures are adopted into a set of purchasing specifications, the fire department owns them. The fire department is saying it knows what the minimum standard is and it wants to exceed it – for whatever reason. There is no qualm nor questioning firefighter safety when riding the apparatus. The safer, the better.

2 One way of performing the second part following the dynamic preload test. In this test, a platen is loaded onto the roof of the cab. The dictionary defines a platen as a “flat plate that exerts or receives pressure similar to a printing press.” This test can also be performed with the cab in a vertical position such as in the illustration in photo 3. (Photos 1-2 courtesy of KME
2 One way of performing the second part following the dynamic preload test. In this test, a platen is loaded onto the roof of the cab. The dictionary defines a platen as a “flat plate that exerts or receives pressure similar to a printing press.” This test can also be performed with the cab in a vertical position such as in the illustration in photo 3. (Photos 1-2 courtesy of KME.)

A concern is how to incorporate “other than standard” safety requirements into the bidding process and how to evaluate the levels of safety specified, proposed, and acceptable to the purchaser. How can a buyer evaluate bid responses when the buyer doesn’t understand what has been specified? How can a seller, supposedly in good faith, influence a prospective purchaser to specify something he himself does not understand? It happens more often than not.

Spec writers, and purchasers in particular, should be aware that anything written in a purchasing specification or proposal specification can be challenged – both internally and in public. Why did you specify that amount? What is the minimum requirement? Why isn’t it acceptable? What’s the difference between a dynamic loading, a dynamic preload, and a quasi-static loading? If you wrote the specs, be prepared to respond.

Several nonfire-service-related documents are referenced below. They are a report by the International Research Council on Biomechanics of Injury (IRCOBOI); the DOT HS 812 061 white paper (report) published by the U.S. Department of Transportation; the United Nations Economic Commission for Europe (ECE) Regulation 29; and a report by the Association for the Advancement of Automotive Medicine (AAAM). Following are direct quotes and my paraphrasing of significant passages from them.

IRCOBOI

The IRCOBOI has conducted annual conferences since 1973. It is a forum for researchers in the field of injury biomechanics. It appears to me that IRCOBOI accumulates and disseminates data rather than establishing criteria or recommendations. Its IRC-15-60, published in 2015 and titled “Test Methods for Occupant Safety in Heavy Truck Rollovers,” contains several statements alluding to why the crashworthiness of commercial truck cabs was addressed:

  • A 1986 National Highway Traffic Safety Administration (NHTSA) study said approximately 1,000 heavy truck occupants are killed in crashes every year.
  • Insufficient survival space in the cab during rollover accidents is the primary cause of death for drivers of large trucks.
  • One study recognized the need to improve truck cab structures to “control and minimize the extent of cab intrusion so that occupant survival space is maintained.”
  • The University of Michigan Transportation Research Institute (UMTRI) reported in 1991 that approximately 60 percent of all heavy truck driver fatalities were associated with rollover accidents.
  • National Transportation Safety Board (NTSB) analysis of 189 heavy truck tow‐away accidents in 1988 noted in many of the accidents that the structural design of the cab did not provide adequate protection for the driver.
  • The survival space concept has been well understood since the 1950s.
  • In the late 1960s, most auto manufacturers incorporated the concept of “survival space” or “nonencroachment zone” within the occupant compartment, which is not to be intruded on in a rollover. In 1969, the published “The Crash Survival Space” discussed the importance of maintaining a post‐crash survival space above the vehicle’s occupant in all crash modes.
3 A representation of a custom fire apparatus cab with a vertical platen applying pressure to its roof. Note that SAE and ECE testing criteria were established for commercial cabs and not specifically for custom cabs for the fire service. NFPA 1901’s Appendix, A.14.3.2 notes, “Manufacturers may test in excess of the standards.” It is the purchaser’s decision whether to specify a manufacturer’s higher testing criteria. The quest for a “safer” cab, while principled, may impede competitive bidding by eliminating otherwise qualified manufacturers. The exact SAE and ECE testing criteria are available online. Purchasers may want to access the same when evaluating cab manufacturers. (Illustration courtesy of author
3 A representation of a custom fire apparatus cab with a vertical platen applying pressure to its roof. Note that SAE and ECE testing criteria were established for commercial cabs and not specifically for custom cabs for the fire service. NFPA 1901’s Appendix, A.14.3.2 notes, “Manufacturers may test in excess of the standards.” It is the purchaser’s decision whether to specify a manufacturer’s higher testing criteria. The quest for a “safer” cab, while principled, may impede competitive bidding by eliminating otherwise qualified manufacturers. The exact SAE and ECE testing criteria are available online. Purchasers may want to access the same when evaluating cab manufacturers. (Illustration courtesy of author.)

U.N. ECE Regulation 29

U.N. ECE Regulation 29, implemented in 1974, established uniform provisions to protect the occupants of commercial truck cabs (including heavy trucks). Original U.N. work on vehicle safety started in 1952, and the 1974 Regulation 29 has already undergone three amendments. Its basic provisions include a frontal impact test, roof strength test, and rear‐wall strength while maintaining a preestablished survival space in the cab. It is interesting to note that the Swedish developed their own test methods that Volvo had been using since 1959. Their requirements are more stringent than the U.N. test criteria.

DOT HS 812 061

In 2015, the U.S. Department of Transportation, National Highway Traffic Safety Administration Office of Applied Vehicle Safety Research, published DOT HS 812 061, a 112-page technical report titled “Heavy Truck Crashworthiness: Injury Mechanisms and Countermeasures to Improve Occupant Safety.” The study was done by the University of Michigan Transportation Research Institute. The objective was to analyze driver injury and loss of life in truck crashes related to cab crashworthiness and to investigate regulations and industry trends in relation to truck occupant protection. Both cab over engine (COE) and conventional engine-ahead cabs were studied. The complete report is available online.

It noted that a 1990 cab crashworthiness initiative was conducted under the auspices of the SAE Cooperative Research Program. It focused on crash statistics, accident reconstruction, occupant dynamics simulation, 90-degree and 180-degree rollover crashes, and roof crushing as well as developing and evaluating recommended test procedures that could be used to evaluate occupant protection in heavy trucks. In addition to the U.N. ECE Regulation 29, the SAE consolidated research data from multiple sources, resulting in the development of SAE J2420 and SAE J2422, which were formally issued in January 1998 and adopted by the NFPA in 2009. They’ve both been tweaked since. The particulars of how the tests are performed and the actual test criteria are irrelevant for this discussion. Ask the cab manufacturers for the particulars.

4 This photo depicts the COE Frontal Strength Evaluation where “the cab is impacted by a rigid platen simulating the rear of a heavy truck trailer.” Testing criteria are intended to increase the survivability within the cab. Cab doors must remain closed after testing. (Photo courtesy of KME
4 This photo depicts the COE Frontal Strength Evaluation where “the cab is impacted by a rigid platen simulating the rear of a heavy truck trailer.” Testing criteria are intended to increase the survivability within the cab. Cab doors must remain closed after testing. (Photo courtesy of KME.)

AAAM

According to its Web site, the AAAM is the premier global professional organization dedicated to saving lives and eliminating injuries associated with road traffic crashes. It is a professional multidisciplinary organization dedicated entirely to motor vehicle crash injury prevention and control. It was founded in 1957 by the Medical Advisory Committee to the Sports Car Club of America by six practicing physicians whose avocation was motor racing. In 2012, it published a report titled “Analysis of Firetruck Crashes and Associated Firefighter Injuries in the United States.” It is the first comprehensive report I have seen that specifically addresses fire truck accidents. Some excerpts follow:

  • Motor vehicle crashes are the second leading cause of death for on-duty firefighters. Fire truck crashes occur at a rate of approximately 30,000 crashes per year.
  • The United States Fire Administration (USFA), an agency of the Department of Homeland Security, cites motor vehicle crashes as the cause of death for between 20 and 25 percent of the annual line-of-duty fatalities.
  • Motor vehicle crashes are the second highest cause of death for firefighters.
  • Despite revising national standards to improve fire truck safety and reduce firefighters’ risk of injury and fatality, the annual injury and fatality rate has remained essentially unchanged over the past decade.
  • Between the years 2000 to 2009, there were approximately 31,600 crashes involving fire vehicles, 49 of which led to the death of at least one fire truck occupant.
  • Approximately 500 firefighters are involved in fatal fire truck crashes each year, and one out of 100 of these occupants dies as a result of the crash. Despite changes in regulations that govern fire vehicle safety, the average fatality rate per year has remained relatively stagnant. Rollovers are the most common crashes that result in firefighter deaths (66 percent of all fatal fire truck crashes).

Interestingly, the basic AAAM conclusion appeared to be increasing seat belt usage and changing the mindsets of firefighters to use them. The structural stability of cabs was not addressed.

Not Job-Specific

The criteria for commercial truck cab crashworthiness were established outside of the fire service. They were adopted (by reference) by NFPA 1901. They were not modified to meet the job-specific requirements of a fire truck. I believe by the nature of their construction, job-specific custom cabs for the fire service appear to be more heavy-duty than their commercial counterparts. But, that argument is left for the apparatus manufacturers to make.

5 This photo shows the “paralleling” of an older custom cab that had rolled onto the passenger side. It is obvious its construction maintained a survivability zone within the cab. Cab construction, safety standards, and testing can be negated by NOT wearing seat belts. (Photo used with permission of Atmore News
5 This photo shows the “paralleling” of an older custom cab that had rolled onto the passenger side. It is obvious its construction maintained a survivability zone within the cab. Cab construction, safety standards, and testing can be negated by NOT wearing seat belts. (Photo used with permission of Atmore News.)

Use caution if spec writers adopt or copy the exact verbiage of an OEM’s claim of exceeding J2422, J2420, and ECE 29 requirements into their purchasing specifications. As previously mentioned, the spec writer may have to define the criteria, justify the decision to specify them, and defend a decision to accept or reject proposals that take an exception to what could be a claim unique to one manufacturer. If that is the intent, make sure you know what the requirements are and understand the sophisticated language automotive and safety engineers use to describe them. Good luck. If the purchaser’s intent is to write a proprietary specification around one cab manufacturer to give the manufacturer an unfair advantage, so be it. That also is a topic for later discussion.

Statements similar to the following are often seen in apparatus purchasing specifications: “The apparatus shall be compliant with the NFPA 1901 issue in effect on the date of contract signing.” The NFPA usually revisits the 1901 standard every five years, and the OEMs will, when necessary, update their product to meet any new requirements. In the case of the referenced J standards and the ECE 29 Regulation, if those testing criteria are changed or upgraded, do the apparatus manufacturers have to retest their cabs? A similar query can be raised about cab heights. Are cabs with flat roofs, those with 10-inch raised roofs, and those with 24-inch raised roofs tested separately? Do they have to be? Should they? One of the criteria when testing cabs is that the cab doors cannot “pop open” when the cab is tested. Does it make a difference if the door tested is a full height door or a barrier-style door? What about a full-height door in a 24-inch raised crew cab? If an OEM changes its door latch mechanisms, does the cab have to be retested? I don’t know. In the next part, I ask fire apparatus manufacturers how they build their cabs.

Be fair to the OEMs who exceed minimum safety standards. Building a better product may not only give them a competitive advantage, it may give them claim to building a safer cab for the firefighters. Seeking a competitive advantage is understandable. Building a safer fire truck is commendable.

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.