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Find a Transportation Engineering Expert →Overview
A transportation engineering expert decides whether a road, intersection, signal or work zone met the engineering standards in force at the time, and whether any shortfall bears on the crash. That is a different question from how the crash happened, which belongs to an accident reconstructionist, and from what a driver could perceive, which belongs to a human factors expert. Most of these cases are claims against a public agency, its design consultant or a contractor, so the fight is usually over which standard applied and how much discretion it left.
The documents are design plans, as-builts, traffic studies, signal timing records, crash histories, maintenance logs, traffic control plans and daily work zone diaries. The first task is often to pin down what was on the ground on the crash date.
The Manual on Uniform Traffic Control Devices, or MUTCD, is the national standard for traffic control devices on all public roads, bikeways and private roads open to public travel 1. The current edition is the 11th Edition, Revision 1, dated December 2025, which replaced the December 2023 text 1. FHWA described Revision 1 as minor technical corrections and editorial changes that do not change the underlying legal requirements 1.
Edition control still matters. States must adopt FHWA's changes within two years of a final rule's effective date, and a state manual or supplement must conform at a minimum to the national Standard statements 3. So the correct text may be a state manual rather than the national one. An opinion should name the document in force in that state on the relevant date, and a report that cites an older edition without explaining why is open to attack.
The MUTCD sorts its text by force. A Standard is a statement of required, mandatory or specifically prohibitive practice. Guidance is recommended practice in typical situations, with deviations allowed if engineering judgment or an engineering study indicates the deviation is appropriate 2. Much of the dispute in a roadway case sits in that gap. A plaintiff's expert may treat a "should" as a duty, and an agency's expert may treat a documented judgment as the end of the inquiry. The manual also limits who exercises that judgment: a professional engineer with appropriate traffic engineering expertise, or someone working under such an engineer's supervision 2.
Age is a separate question. Non-compliant devices on existing highways are brought into compliance as part of systematic upgrading 2, so a device that does not match the current edition is not automatically a violation. The expert reads the compliance provisions and any target dates before calling it one.
Design standards depend on the road. Projects on the National Highway System use the standards the Secretary approved 4, which include AASHTO's A Policy on Geometric Design of Highways and Streets, 7th Edition, 2018, as incorporated by reference 4. Federal-aid projects off that system follow state law and state design standards 4.
Clear zone is a common example of the limits of a design rule. FHWA describes it as the roadside border area available for safe use by errant vehicles, with a desired minimum width that depends on traffic volumes, speeds and roadside geometry 5. It is not a controlling criterion requiring a formal design exception, but an exception still has to be noted, approved and documented 5.
Work zone cases add contractors and traffic control plans. Under Part 6 of the MUTCD, a plan should be prepared and understood by all responsible parties before the site is occupied 2. Devices in construction areas using Federal-aid funds must conform to the MUTCD 3. Agencies must use positive protection devices in work zones with high anticipated operating speeds that give workers no means of escape from motorized traffic, unless an engineering study determines otherwise 6.
Agency safety studies carry a federal limit. Data compiled or collected to identify or plan safety improvements under listed federal programs is not subject to discovery or admissible in a Federal or State court 7. The provision was section 409 until a 2021 renumbering and is now 23 U.S.C. 407 7. In Pierce County v. Guillen, the Supreme Court construed the privilege narrowly: it covers material compiled or collected for the federal program, not material compiled for unrelated purposes 8. So the source of each crash record matters, and an expert should know which materials a court will let them rely on.
Look for a licensed professional engineer with traffic or highway design experience on the type of road in dispute. The Professional Traffic Operations Engineer certification adds tested traffic operations knowledge. A civil engineer without traffic experience may suit a drainage or pavement question better, an accident reconstructionist addresses speed and avoidance, and a lighting expert addresses visibility at night.
The current MUTCD is the 11th Edition with Revision 1, dated December 2025, and a state manual must conform at a minimum to its Standard statements.
Case Types
Signal timing, sign placement and pavement marking claims under the MUTCD
Roadway geometry, sight distance and curve design disputes
Clear zone, roadside obstacle and guardrail claims
Work zone crashes and traffic control plan failures
Claims against a public agency for failure to install or upgrade a device
Design consultant and contractor liability on highway projects
Pedestrian and bicycle crossing design disputes
Disputes over which edition of the MUTCD or state manual applied
Qualifications
Related Specialties
FAQ
Look for a licensed professional engineer with direct traffic or highway design experience on the type of road in dispute. The Professional Traffic Operations Engineer certification requires a professional engineer license, work experience in traffic operations and a passing exam score, and it is useful where signals, signs or operations are at issue.
It depends on the state and the date. The current national text is the 11th Edition with Revision 1, dated December 2025. States adopt federal changes within two years of a final rule's effective date, and some use a state manual or supplement. The expert should name the document in force in that state on the relevant date.
A Standard is a statement of required, mandatory or specifically prohibitive practice, and it typically uses the word shall. Guidance is recommended practice in typical situations and typically uses should. Deviations from Guidance are allowed if engineering judgment or an engineering study indicates the deviation is appropriate.
Some cannot. 23 U.S.C. 407, formerly section 409, bars discovery and admission of data compiled or collected for listed federal safety programs. The Supreme Court read the privilege narrowly in Pierce County v. Guillen, so material compiled for unrelated purposes is not protected. State practice and the source of each record matter.
The MUTCD places responsibility for temporary traffic control plans and devices on the public body or official, or the owners of site roadways open to public travel, having jurisdiction for guiding road users. Contract documents then allocate duties to contractors, so the expert reads the plan, the contract and the daily records together.
In general, transportation engineering expert fees are determined by the expert themselves, based on a variety of criteria. Among those criteria are licensure, years of agency or design experience, testimony history and the scope of site work. Vident does have some influence over expert fees by comparing experts within a specialty, but ultimately it is a personal decision by the expert.
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