93093 - Traffic Accident Reconstruction M

Learning outcomes

The aim of the course is to teach the student the fundamental principles of Forensic Engineering. At the end of the course the student is able to manage advanced techniques for the technical and kinematic reconstruction of road accidents and, consequently, for the continuous improvement of traffic safety.

He is able to:

- evaluate how the different types of set-up and the active and passive safety devices affect the dynamic behavior of a vehicle;
- conduct inspections and surveys on the site of the accident and on the vehicles involved;
- identify the causes in humans, infrastructure and vehicles;
- develop motion calculations;
- independently draw up a written paper correctly.

Course contents

The student accessing the course in asked to know the basics of physics and mechanics. He has to be able to use the computer applications of the Office family (Excel, PowerPoint, Word) at an advanced level. Those software are provided free by the University with a student license. Lessons’s language is italian. In order to follow lessons and to use the provided teaching material, the student is asked to speak properly the italian language.

The course is mainly attended by students from mechanical and civil engineering. The teacher will take into account different basic technical background of both during the course. The course aims to combine the practical aspect with a theoretical approach of the taught topics. Specific exercises, possible visits to companies, as well as seminars with professionals in the sector, will be planned.

The following topics are covered:

Introduction: forensic engineering elements; application principles; the role of the auxiliary of justice and his operation areas; differences between CTP, CTU and Expert; judicial and extrajudicial activity. Responsibilities of the technical, civil / criminal, contractual and non-contractual consultants. Current obligations.

Regulatory context: sector legislation; traffic laws; implementing regulation; appendices; decrees on the road’s characteristics; intersections and barriers.

Mechanics of locomotion: kinematics and dynamics characteristic equations; the wheel; the adhesion phenomenon; tires in general and their characteristic parameters; soil interactions; derive; drifting; suspensions; viscous and spring dampers; project choices and seek for optimal using conditions on the road; set-up angles including camber, convergence, caster and ackermann; experiments on models.

Motion resistance and lateral forces: aerodynamic resistance; tires rolling resistance; path resistance; interaction between tire and infrastructure; centrifugal force; wind thrust; effect of the road’s gradient; traction diagram.

Steering: devices; kinematic steering; footprint of road vehicles with two or more axles; dynamic steering; oversteer and understeer condition; critical speed.

Braking: general information; braking devices; grip curves on different road surfaces; activation transient; braking space and time.

Active and passive safety: general framework of active safety systems in road cars; evolution and state of the art; ADAS and “Safety assistant” systems. Design and operating criteria of passive safety systems; historical evolution of the airbag and passenger restraint systems; controlled deformation of the veichle; the importance of crash tests for designing passive safety devices for vehicles; frame; cockpit and infrastructure. Operation, data analysis and usability of the black box.

Findings on a crash site: search for clues. Survey of planimetric conditions, anomalies, road signs, presence and efficiency of protective devices, presence of lighting sources, visibility; UNI standards; traditional techniques; laser scanners; photogrammetry.

Surveys on vehicles: search for clues; troubleshooting; survey of deformations; black box reading; survey of seat belts conditions; state of the speedometer; chrono-tachograph recordings.

Elements of traffic psychology: cognitive load; sightability of danger, also related to road’s conditions; danger perception and reaction; central and peripheral vision. Characteristic times.

Peculiarities of road accidents types: road accidents’s classification: axial impacts, side impacts, rollovers, accidents with vulnerable users.

Examination of the pre-impact, impact and post-impact phases: 'backwards' and 'forward' techniques; identification of the impact point; followed trajectories; kinematics of the material point; energy balances; momentum conservation principle; variability of results and their usability limits; evaluation of the dissipated energy in permanent damages to veichle; systems of equations; impact injuries and relations with the medical examiner. Avoidability of the accident: identification of alternative behaviors that would have led to a missed collision and evaluation of their collectability.

Practical exercises: field survey of characteristic parameters; photogrammetry; numerical exercises.

Readings/Bibliography

Reference texts:

- A. Orlandi, Mechanics of Transport, Pitagora Editrice

- G. Genta, Vehicle Mechanics, Levrotto & Bella

- A. Pietrini, Approach to the reconstruction of road accidents, EGAF

The teacher provides teaching material and slides through a OneDrive shared folder.

Teaching methods

Lessons and exercises will be held in classroom and / or through Microsoft Teams, while practical exercises will be held outside. For some exercises it is necessary to have a performing Windows PC, on which specific applications will have to be installed.

Visits to companies (Ducati Motor Holding, Maserati, Lamborghini, Ferrari, Toro Rosso, Wind Tunnel, ...) may be provided only for students enrolled in the course. Access is not guaranteed as it is subjected to the availability of the host companies during the course period.

Assessment methods

The final exam is composed by a preliminary PowerPoint presentation – that must be shorter than 10 minutes - of a technical paper on a topic agreed with the teacher. It must be strictly related to the course teaching area. The work must be done individually. Exeption is for topics that include the execution of practical tests. For those is therefore possible to cooperate in pairs.

An oral interview follows. The candidate has to answer some questions regarding topics taught during the course.

An high level of knowledge related to the student techical report, the achievement of an organic vision of the topics taught during the lessons combined with their critical use, the demonstration of being able to master expression and specific language will be positively evaluated.

The mostly mechanical and / or mnemonic knowledge of the subject, the lack in the ability of synthesis and analysis and / or a correct but not always appropriate language will lead to a discrete evaluation. Training gaps and / or inappropriate language – even for basic exam’s topics - will lead to a barely sufficient evaluation.

Training gaps, inappropriate language, lack of orientation within the bibliographic materials offered during the course can only be evaluated negatively.

Office hours

See the website of Alfonso Micucci

See the website of Mattia Strangi