Preparing efficient vocational truck spec’s

By Christopher Lyon, NTEA Director of Fleet Relations
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This article was published in the April 2020 edition of NTEA News.

Vocational vehicle specifications serve as building blocks for a fleet and provide financial responsibility for the end product. Efficient specifications can lower an organization’s overall acquisition and life cycle costs. They help eliminate guesswork, enabling companies to provide customers with the envisioned end product. Poorly done specifications often result in time-consuming, expensive rework. Avoiding this can allow vendors to reduce financial liability when responding to purchase solicitations — in turn, potentially leading to cost reductions.

How it’s written makes a difference
Effective communication is critical to ensuring well-written specifications and providing the best value for capital spent. There are several types of spec’s, and understanding their differences can be important when it comes to final product and price.

Generic specifications are written to allow multiple vendors and suppliers to comply without making unreasonable changes to their standard products. This can be a useful format for truck equipment when used in competitive bid situations.

Proprietary spec’s incorporate features unique to a certain make or model and are written around a specific unit, excluding all others. Advantages include obtaining a product only available from a sole source or if the spec’ is written around the idea of standardization and can include multiple vendors. Valid selection criteria is key — proprietary spec’s are not effective when used to incorporate unique features for a specific make or model to give advantages to potential vendors during a competitive bid process.

Predatory specifications are written to artificially disqualify a single vendor or make them take unacceptable exceptions to specifications. These are not considered an effective practice and should be avoided.

Four common types of specifications can be written — engineered, functional, performance and hybrid.

Engineered spec’s include the most detail and require a high level of engineering expertise. The writer assumes a significant amount of liability for the final product but has complete control over it. In most cases, these are used for specialized, customized offerings and often result in the most expensive end product with long production times.

Functional spec’s describe intended equipment usage but provide minimal guidance for design. While easy to write, they rely on vendors to interpret requirements and final product applications. This leaves little control over design and makes it difficult to standardize components on a global level.

Performance spec’s are similar to functional but incorporate specific requirements for the completed unit (e.g., crane lifting capacity or maximum operating vehicle speed). They’re easy to write and provide flexibility to vendors; however, there is less control over final design and standardization.

Hybrid or composite spec’s combine the best features of engineered, functional and performance. The writer can fully define all requirements as well as incorporate standard components without being excessively restrictive to vendors.

Don’t rely on the past
Some fleet managers stick with what worked previously and won’t go beyond manufacturer changes from model year to model year. While this may sound like a concrete idea, it can result in outdated and inefficient operations. Take a step back and consider your current equipment functionality. Is the equipment being replaced the most efficient for the task? Have job requirements shifted over time? Change can bring opportunities to increase efficiency, so it’s important to overcome the mindset of replacing equipment with comparable items.

Beginning the process
Several steps are necessary for writing effective specifications — starting with defining the application. Don’t make decisions based on what everyone else is doing or assume past needs equal current. Look at operating environment and drive and duty cycles, and identify valid functional requirements, such as payload and dimensional considerations. Define performance conditions like road speed and gradeability, and outline design constraints like operating environments, overall weight, vehicle dimensions, and other regulatory barriers.

It’s critical to design second units such as body and auxiliary equipment before the chassis. Avoid the pitfall of buying a chassis and making it work. Once all the details are finalized, then design the chassis and write the specification.

NTEA’s Vehicle Specification Process Guide, a free member resource, helps improve the spec’ development process by applying leading techniques widely recognized by industry professionals. Learn more at