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Patient Care

How to Develop a Fleet Replacement Strategy


Next to manpower, the biggest outlay in EMS is vehicles and equipment. These days, a fully loaded and clinically equipped ambulance is a six-figure purchase. The development of a comprehensive fleet strategy is a key financial, operational and corporate activity. In order to inform any fleet and vehicle replacement strategy, several factors must be taken into consideration.

Key Considerations

A fleet “industry standard” states that that an organization should have a fleet size that equates to 133% of its peak-of-day operation. In other words, if an agency needs 20 ambulances to cover its highest hour of requirement, then it should have a total of 26 vehicles to cover for preventive maintenance, off-site repair and any unforeseen issues. The triad of mileage, age and cost are key factors that will inform any plan. The useful life of a vehicle is normally between 150,000 and 250,000 miles at an age of between 4–7 years. Cost in terms of total maintenance versus initial purchase cost is also very important (the purchase cost of the vehicle is a known number, the total investment in its life must be understood). For any fleet, be it a commercial carrier or EMS and fire departments, vehicles must be available for service and mechanically viable in order to remain operationally efficient.

As with every decision in modern-day EMS, data and the ability to understand it play a major part in developing your strategy:

Vehicle Availability

Understanding lost unit hours (UH) and downtime for every piece of equipment is important. Establish a database to count the time or days each vehicle is not available for service due to a mechanical issue or period of preventative maintenance. Preventative maintenance is important to consider because comparing the out-of-service time will allow the type of vehicle and consideration of a different style to become clearer. An example would be to compare how often preventative maintenance is done between a Type III and a Type I heavy-duty in a high-mileage system. In this example, extended service cycles may show an advantage for the medium-duty chassis, although fuel mileage may be sacrificed.

Repair Costs

Review all repair and preventative maintenance costs. Preventative maintenance allows the comparison of cost of chassis styles versus fuel consumption. Consider cost per mile and fuel miles per gallon if possible. Vehicles trending up in cost per mile and down in miles per gallon could signal possible areas of failure. Evaluation of this data will begin to show areas where additional presentative maintenance measures can be put in place to reduce cost such as early detection of coolant leaks from failing water pumps or radiators, fouled diesel injectors reducing fuel miles or even DPF (diesel particulate filter) clogging to name a few.


No pun intended, but when a vehicle fails mechanically, break down the data into why a road or recovery call was necessary. If a particular reason for road failure is evident, comparison of the data across the whole fleet may reveal a trend that needs to be addressed. Not all failures are chassis failures. Many failures can be traced back to an inadequate clinical module mounted on the ambulance chassis, which in design or quality of construction may not meet the rigors of the service provided.

Squeezing Out the Lemons!

Finally, combine the assembled data into one place to compare and contrast availability and cost. Vehicles on top of the list are the most dependable, have the lowest costs and highest availability, and are able to support the operational need. Those on the bottom provide little or no operational support. The decision is then whether to replace the vehicles that are draining resources or find the causes for the issues and make the necessary adjustments. Mileage and time alone do not provide enough data to make solid fleet decisions. You may discover that the oldest, highest-mile vehicle ends up being the most reliable workhorse of the fleet. Using all three data sets (vehicle availability, repair cost and breakdowns) to set a base point and data collection to determine replacement is the most efficient process.

Deciding on Your Next Purchase

Fleet selection should be based on environmental, as well as operational, conditions. The continental U.S. has a range of terrain and environments that spans from Arctic to desert and mountain to plains—one size does not fit all. To clarify vehicle types:

  • Type I: These are pickup-truck style or the heavy-duty/AD medium-duty truck chassis. These will have a clinical box module on the original chassis construction with various options for seating and equipment storage design. A larger version on a truck chassis is known as a Type I HD–heavy-duty.
  • Type II: Van, sprinter or transit style. These vehicles are always purchased new and usually have less equipment storage space compared to other types. They are typically more fuel efficient and less costly on maintenance due to total weight.
  • Type III: As with the Type I, these consist of a van-style form and clinical box mounted on the rear chassis. They are usually smaller and more maneuverable compared to the Type I and HD/AD. They come in a range of main dealer chassis and are diesel with DEF (diesel exhaust fluid), gasoline engine and now the potential for CNG (compressed natural gas).

Vehicle Standards

The construction and use of guidelines for the American ambulance fleet is at somewhat of a crossroads at the current time. There are three ambulance standards either in existence or under developmental review: the GSA (General Services Administration) KKK-1822-F Star of Life standard, the NFPA 1917 standard and the CAAS GVS (Ground Vehicle Standard). Depending on your location, additional regulations may be in effect as directed by each state.

When developing a fleet strategy, it is important not to attempt to second-guess which of the standards may be in effect when the final choice needs to be made. The design of a vehicle should comply with the standards in current use and, if necessary, add enabling components to be able to retrofit as needed to meet future standards. Always look for the best in the design and build process as possible; by doing this, the vehicles will cost less to meet the future standards if rechassis process is the choice or to just upfit to a new style for equipment such as power cots and crash-tested cot retention mounts.


Over time, the choice of vehicle could become outdated quickly with changes in medical science. If the vehicle replacement time frame is set from 5–7 years, the vehicle design committee should include the operational medical director to provide the “crystal ball” of future changes and additions required.

For example, over the last 5–7 years, clinical, technical and safety factors have all changed the design, construction and use of EMS vehicles. Patient restraint, crashworthiness, more complex interiors, less complex and cluttered interiors, manual and powered cots, loading systems, warmers, coolers, solar panels and DEF (diesel exhaust fluid) tanks have added to the conundrum of fleet planning and vehicle construction.


Allied to the future-proofing is the question of weight. Available vehicle payload is addressed in some of the vehicle standards, but the questions that need to be answered regarding the choice of vehicle include:

  • How much equipment is needed?
  • What is the weight capacity?
  • What are the needs of employees and the work environment where the vehicles will be operating?

All component parts of the vehicle build must be combined with human factors. A vehicle with a remaining payload after equipment of 1,000 lbs sounds good until each seated position is counted, with personnel weight assigned as between 171–175 lbs. per person dependent on which standard is followed.

A typical ambulance will have at least three seated positions in the back and two in the front; accounting for five persons at 171 lbs equals 855 lbs of weight, leaving 145 lbs for patient weight. An extreme example perhaps, but it brings into focus that our patients and equipment are not getting lighter and operating vehicles consistently at or over the functional weight capacity severely reduces the life of the vehicle and safety of operation.
This article is primarily based on ambulance fleet design and strategy, but in the planning and purchase of rapid response and supervisor vehicles, weight is also a critical factor and many of these types of vehicle are regularly overloaded with equipment for the “just-in-case” situations.

Operating Environment

Understanding the requirements placed on your vehicle fleet in regard to both geography and system design is of paramount importance.

Requirements in a static, station-based system may be different than a mobile, system status management (SSM) dynamic-deployment operation. The difference in the two from a fleet design perspective is vast. House or station-based vehicles do not tend to idle at as high a rate and therefore experience less idle wear on engine components. Conversely, vehicles posted on street corners idling do not normally exhibit signs of wear from cold starts with full throttle operation. In terms of physical hours run, SSM-posted vehicles incur far more usage time and equivalent miles than actually shown on the odometer.

New or Rechassis?

A rechassis is when the vehicle is split into its two component parts—the clinical ‘box’ on the back and the cab and the running gear. This offers the ability to lower cost, which can be leveraged to gain operational effectiveness and upfitting to new equipment.

Buying new allows for updates and fitting of equipment more effectively, but cost is considerably higher. Today, as the environment surrounding ambulance standards continues to move forward, the cost of new or rechassis vehicles will increase. These increases are necessary, but finding the way to absorb these increases is important.

The Fleet Manager’s Role

Finally, a key question must be asked: In clinical practice would you allow your local shop mechanic to conduct an intubation, cricothyrotomy or titrate the medication to the correct dosage? The answer is probably very clear. Conversely organizations might consider looking beyond the medical workforce to fill this vital vehicle life support task. A qualified and experienced fleet manager may just be worth the fuel, downtime and mechanical trouble that you will be saved. As an industry we are good at letting staff “have a go” at the non-clinical tasks, hoping that we will cope. The evidence suggests we should employ a fleet professional to drive our success and manage the resource that we rely so heavily on to deliver excellent patient care.

Why Maintenance Matters

Preventive maintenance is a great way to ensure the patient never has to wait any longer than is necessary for the ambulance, or wait on the side of the road for a replacement vehicle to arrive.  

Data is as much a key requirement in caring for vehicles as a tool box full of wrenches. Having comprehensive vehicle records is essential and, in most states, is a permitting requirement. It is certainly a “must have” to attract any form of formal accreditation such as CAAS (Commission on Accreditation of Ambulance Services).  

Vehicle records and their absolute maintenance provide evidence of failures and the frequency of those events and may well lead to clues about particular vehicle brands or engine types.  

Comparison and contrast of all vehicle data reveals trends and provide insight to key equipment types as well as informing maintenance or replacement programs.  

Understanding when key components break on any particular type of equipment allows that piece or part to be serviced or replaced before it critically fails on the street on a call.

Establishing a mean time between failures (MTBF) chart for key equipment and abiding by it will ensure that unscheduled maintenance remains at a minimum. The term “unscheduled maintenance” is another code word for cash hemorrhage—if a truck and its crew have to leave the street with zero notice then unit hours (EMS currency) are wasted, the net effect being that there is one less vehicle available on the street when the carefully constructed data-driven demand analysis says you need them. Poor maintenance potentially equates to poor patient service.

There are many types of maintenance tracking systems in the marketplace, but consideration should be give to systems that capture:

  • Assets: Your vehicles by their VIN and type.
  • Retired Assets: Having data on old vehicles and vehicle types allows for comparative analysis against new or updated units.
  • Work Orders: Key information that shows who did the work (it may be possible to benchmark and performance-manage mechanical output as one mechanic may fare better at one repair versus another).  Also a record of parts used on every truck allows for cost-benefit analysis of the relative worth of a vehicle, particularly as they near end of life and determinations need to be made over disposal or continued service.
  • Preventive Maintenance: Again the simple mantra of a good PM program is to “catch it before it fails.” It is the public health program for vehicles. A sufficient understanding of other fleet metrics will allow the timing and intensity of servicing to be adjusted to ensure a cost-effective level of treatment.  
  • Inventory: Understanding inventory by both what is on the shelves and what has been fitted to the vehicle is important. As with all logistic principles, understanding throughput informs stock control and how much fast-moving items are required on the shelf and how much is required to be readily available elsewhere for rapid delivery.

Proactive and Reactive Devices Improve Performance

To assist with the task of keeping crews safe, as well as monitoring the behavior of other road users, both proactive and reactive devices are available in the EMS marketplace.

In recent years the advent of dash cams has provided video evidence of incidents and accidents as they occur. They serve a purpose in identifying via recorded loop technology what’s happened, more often than not who was at fault, and the exact actions—or distractions—of the vehicle operator.  By and large, they do not play an active role in preventing the accident or crew behaviors, but they form the basis of after-action reviews, ensuring that the workforce understands the need for safe and skilled vehicle operation.

The other style of system in the current marketplace monitors data points in and around vehicle operation, such as the G forces that a vehicle encounters as a result of rapid acceleration or deceleration, tilt and even “bounce” via the use of vehicle-mounted gyroscopes.  Once an operator has been identified by logging onto the system via a fob, sensors then detect the application of seat belts, emergency lights and siren, indicators and braking, and then records the overall driving habit of the individual and by aggregate, the organization.  

In such systems the required operating parameters for any vehicle can be set, such as upper speed, tilt encountered in cornering and over or under forces at work in both acceleration and deceleration.  Once limits have been set, an audible warning alarm or alert can warn the operator that they are nearing the specified limits and to take appropriate and correcting action.  

The overarching aim of systems such as these is to avoid the accident in the first place, rather than watch it back on the video afterwards, although vendors are now able to offer a bundle package combining both pro- and reactive systems at the time of sale. The added bonus of driver monitoring systems is that they allow an organization to amass a body of safe driving evidence to drop insurance premiums based on the excellence of vehicle operation.  

Linking back to vehicle maintenance, less vehicle contact equals less expensive repair and lost unit hours, while safe, skilled and monitored vehicle operation decreases wear, prolongs life (of both provider and vehicle) and reduces overall maintenance cost.

Dan Fellows joined the Richmond Ambulance Authority in 1995, where he has amassed two decades of emergency vehicle maintenance and design experience. He is a graduate of the Nashville Auto Diesel College, a licensed Virginian State Inspector, and a Stryker, Excellence and Ford factory-certified technician.  

Rob Lawrence, MCMI, is chief operating officer of the Richmond Ambulance Authority. Before coming to the USA in 2008 to work with RAA, he held the same position with the English county of Suffolk as part of the East of England Ambulance Service. He is a member of EMS World’s editorial advisory board and host of the Word on the Street podcast.

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