This document provides an overview of forensic engineering. It discusses that forensic engineers apply scientific knowledge to events that may lead to legal debates or court cases. The four main engineering areas are civil, electrical, mechanical, and chemical, each with various specialties. Forensic engineers investigate things like structural failures, fires, and vehicle accidents. They analyze physical evidence from the scene and vehicles/structures to determine factors like vehicle speed or whether proper standards were followed in construction. Accident investigations aim to establish what happened and identify vehicles and locations. Physical evidence like skid marks, debris, and vehicle/victim injuries are important to collect and evaluate properly. Signaling and control systems can fail due to equipment faults, cable issues, or undetected design

1. Forensic Engineering

2. Introduction
• The definition of engineering is the science of putting scientific knowledge to practical
uses.
• a forensic engineer is one who applies scientific knowledge to an event that may lead
to a debate, formal argument, or a court of law
• four main areas in engineering:
• Civil
• Electrical
• Mechanical
• chemical
• Within these main areas there are a myriad of specialties

3. • civil engineers may specialize in structures, foundations, soils, hydraulics, road
construction, sanitation, or the environment.
• Electrical engineers may specialize in power, electronics, computers, communications,
or process control.
• Mechanical engineers may be involved in vibrations, metallurgy, thermodynamics,
engines, or heat transfer.
• Chemical engineers deal with processes, biotechnology, nanotechnology, minerals, and
reactions.
• engineer may specialize in computer software or computer hardware

4. Types of assignments
• two cars collide and the respective insurance companies or attorneys wish to
determine who was at fault - soon after the collision when the insurance company
needs to determine the liability of their insured
• years after the fact when a law suit has been filed, and attorneys wish to determine
the strength or weakness in the case they represent.
• after a natural disaster such as a storm that collapses various roof structures
• a fire that destroyed a residence.
• the insurance company may need to determine the extent of the damage
• Failure of the builder of the structure to follow recognized standards

5. Things that can be done
• right to cause the negligent builder to pay for the repairs of the structure if it was
improperly constructed
• a failure of the dryer caused the fire

6. • National Fire Protection Association (NFPA)
• American Society of Testing and Materials (ASTM)
• American National Standards Institute (ANSI)
• Society of Automotive Engineers (SAE)
• American Society of Metals (ASM)
• Underwriters Laboratories (UL).

7. Accident investigations

8. In forensic investigation of road accident cases, it is
necessary to establish the following:
• That an accident has actually taken place. It may not be a subterfuge to conceal some
other crime.
• The identity of the location where accident took place, particularly on highways.
• The identification of the vehicle in a "hit and run" case.
• To identity the driver in a case where the owner of the vehicle alleges theft.

9. Sources of Physical Evidence in the Investigation of
Road Accident
• The Crime Scene
• The vehicle – may be one or more, its type, direction and position.
• Track marks like tyre impressions of the four wheels, which are found either at sharp turns
or where the vehicle has been reversed.
• Broken or damaged parts of the vehicle.
• Greases and lubricants.  Glass pieces of various shapes and sizes.
• Paint chips or smears.
• Skid marks.
• Dust, dirt or other debris, caked or otherwise, fallen from the suspect vehicle at the time of
impact.
• Personal or vehicular articles left at the scene.
• Drag marks of the loaded material (e.g., logs of wood or any other items).

10. • The Vehicle
• Finger and palm prints, tool-marks and fabric prints.
• Hairs, fibers, bloodstain or skin pieces from the victim.
• Small broken parts or fragments of the vehicle or the article hit. Broken glass, paint, greases
and lubricants from the vehicle, which was hit and control samples from the suspected
vehicle for similar articles to those left at the scene.
• Dust, mud and dirt from the scene of occurrence, from the victim or from the driver.
• Cigarette and 'Bidi' butts from the vehicle.
• Mechanical fault in the vehicle.
• Evidence related to changes in paint and numbers on registration plate, serial number on
engine and chassis.
• Evidence related with overloading of vehicle.
• The load on a vehicle may leave characteristic smell on the way through which it has moved.

11. • The Victim
• In addition to dust, dirt, paint, glass pieces, greases and lubricants and tyre marks, which
may be present on the clothes or on the body of the victim, the following important evidences
can also be found at the scene:
• 1. Injuries.
• 2. Blood, fibers, hair and skin for control samples.
• 3. Alcohol and narcotics in the body, if the victim had taken the same.
• 4. Signs of disease (from post-mortem report).
•

12. Collection of Evidence
• Before the collection of evidence, take photographs and make sketches of the scene at the earliest
• The photographs and sketches should be taken in such a way that the location of accident scene can be
fixed by including some of the prominent fixed landmarks like milestone or any hording etc.
• The photographs should also be taken in a way to show the identity of the vehicle (kind of vehicle, its
number plate etc.).
• Before taking away the vehicle, note down the reading of speedometer, record the temperature of the
vehicle, of the atmosphere and of the water in the radiator.
• Ascertain the quantity of fuel in the vehicle, examine the whole area for any physical clues and collect any
loose evidence, which is likely to get lost in transit.
• Examine other parts of the machinery thoroughly.
• Collect various evidences like skid marks, broken parts of machinery, bloodstains, fibers, hairs and alcohol
glass, paint, soil including dust and debris, greases and lubricants, cigarette and 'bidi' butts from different
sites separately and wherever necessary collect control samples also.
• Collected evidence should be documented with the help of notes and photographs and then packed
properly/securely in glass containers or cellophane envelops depending upon the nature of the evidence.

13. Evaluation of Physical Evidence
•  Is the vehicle itself a cause of the incident?
• Speed
• The ability of the driver
• The performance of the vehicle
• The condition of the road
• The speed can be calculated by the following methods:
• From the length of skid marks;
• From the radius of curved scuffmarks;
• From the extent of vehicle damage

14. Skid Marks
• left by wheels, which are no longer rotating
• caused due to the wheels sliding across the surface of the road
• friction between the tires and the road surface that is slows down the vehicle
• short-lived type of evidences
• play important role in the successful reconstruction of a road traffic incident

16. • speed and the nature of the surface of road results in the distance taken by the
vehicle to come to a halt
• Thus if the coefficient of friction (µ) between tires and the road surface can be
measured
• a reliable estimate of the speed (v) can be calculated from the length of the tire marks

17. Curved Scuffmarks
• cornering force, curved path- friction between the tires and the road surface or when
maximum speed exceeds
• the vehicle sideslips and leaves characteristic tire marks
• marks are curved and have a pattern of diagonal striations across them
• the driver in most of the cases loses control of the vehicle.

18. Extent of Vehicle Damage
• damage to the vehicle is mostly directly proportion to the speed
• the faster the vehicle is traveling (when it hits something) the greater will be the
damage

19. In summary
• The main purpose of whole forensic investigation of accident is to establish the `cause'
of the incident.
• In the investigation of road accidents involving vehicles, physical evidences play a
very important role. Their nature therefore needs to be understood properly before
they (Physical evidences) are collected.
• In most of the hit and run or accident cases the vehicle involved may carry traces
from the scene of occurrence or from the other vehicle involved, or the victim.
• Skid marks are the marks left by wheels, which are no longer rotating. These marks
are characteristic in appearance and caused due to the wheels sliding across the
surface of the road.
• Vehicle damage alone will not enable the exact speed of a car to be calculated as the
extent of the damage depends on the change in speed brought about by the collision.

20. Videos to watch
• https://www.youtube.com/watch?v=DKpMOfcHzkM
• https://www.youtube.com/watch?v=dKCw0cfrvD8

21. Failure of signaling and control
systems

22. • signaling maintenance
• prevent failures by planned maintenance activities and intelligent anticipation
• Maintainers - responsible for signalling maintenance
• In case of failure
• Report to Network Controllers
• Reporting and Recording Failures
• All failures shall be fully investigated and all details must be documented

23. Investigation of Signal Failure
• All voltage and current readings associated with the equipment
• Earth leakage tests
• Cable condition assessment
• Visual inspection of all equipment
• Terminal condition and tightness
• Track circuit integrity (eg. walk the track)
• Point layout inspection - Lock and detection, fasteners, rail condition (stock rail and
blade), geometry.
• Ask questions and seek answers from Network Controllers, Train Crews etc.

24. 1) Equipment faults
Faults due to equipment failure are the most common type of signalling faults. In most
cases they will result in “Rightside” failures. E.g. Point detection and track circuit
failures. These faults occur almost daily on most railway systems.
They are not directly unsafe. However they can indirectly result in an unsafe condition
arising as they can force the operator to revert to manual operation of the signalling
system and trains have to be authorised to pass signals at danger. Unsafe situations
can then arise, due to the potential for miss-communication between operators and
drivers.

25. 2) Cable faults
Cable faults are more common in older signalling systems, where the trackside cabling
and wiring inside the signalling equipment rooms is starting to deteriorate. In most
cases, cable failures will result in right-side failures. In the worst case, a core to core
cable or wiring fault can result in a Wrong side Failure.

26. 3) Design faults not detected by the checking and
testing process
Note design errors can apply to all technologies-
mechanical, relay based. If a design error isn’t
detected by the checking and testing process, it may
lie dormant perhaps for many years.

27. 4) Faults due to errors by maintenance
personnel when replacing or resetting faulty
equipment
a) Bletchley-Latched relay replaced in wrong state.
=> Resulting in points moving underneath train

28. Installation errors not detected by the inspection and testing
process. (e.g. Clapham Junction)
Operational errors by Drivers and Signalmen compounded by
deficiencies in the signalling system. [e.g. Quintinshill, Hawes
Junction (Signalmen’s error), Harrow and Wealdstone,
Lewisham. (Driver’s error)].

29. Ergonomics

30. Introduction
• relationship between the work environment and humans.
• Ergonomically designed environments optimize efficiency and ease of the work
environment.
• walking
• surfaces, chairs, tables, work benches, and tools
• Illumination - Too much or too little illumination can be detrimental to the work
environment

31. Illumination
• Quantity of light intensity
• Glare
• Flicker
• Shadows
• Contrast
• Color of the light
• High light levels affect what we see

32. Why ergonomics?
• Brown lung, which was unknown prior to the invention of textile factories and flour
mills, resulted from the long-term inhalation of textile particles or flour particles.
• Black lung, resulted from the inhalation of fine coal and dirt particles.
• Disfiguring injuries were so common with some types of equipment
• It was possible to guess a person’s trade by the location of their scars, the number and
placement of gnarled joints and crooked fingers, or the pattern of lost limbs.

33. Vision
• red-green color recognition deficiencies - anomalopia and is an inherited condition
• red be used for the background color on signs that warn of danger, yellow for signs
that caution, yellow-orange for warning signs, and orange-red for biological hazard
signs. Some of these background colors are colors commonly confused by persons with
anomalopia
• a person with color deficient vision is put into a situation where it is very important
that he recognize the meaning of a machine indicator light or sign by its color, a
mistake may occur
• people with anomalopia should not be allowed to drive a car or operate machinery?
• provide secondary visual cues

34. • not only are the traffic lights red, yellow, and green, but they are always positioned
the same way.
• The red light is always on top, the yellow light is always in the middle, and the green
light is always on the bottom
• The use of position and shape provide an alternative to color-only recognition
• the operator can know by its position whether it is a “good” green light, or a “bad” red
one
• the shape of the light can also be a visual cue
• A green light on a machine control panel might be made to always be round in shape,
while a red one might be required to be square.

35. Sound
• Alarms in factories
• Train horn signals (95 DB)
• Car Horn – windows rolled up ? 70-75 DB
• To hear the warning horn of a train, the sound of the horn inside the car should be at
least 3 to 5 db louder than the sounds generated within the car itself.

36. Guarding
• Point of Operation: The point in the machinery where cutting, shearing, shaping,
material removal, or forming operations are performed.
• Power Transmission Equipment: The machinery components that transmit power
through the machinery. This includes sheaves, belts, connecting rods, cams,
couplings, chains, gears, cogs, flywheels, spindles, sprockets, and shafts.
• Other Moving Parts: This includes the moving parts of the machinery not directly
associated with the first two categories such as feed mechanisms, moving fixtures,
control mechanisms, and so on.
• An easy rule to consider with respect to whether guarding is needed is could a person
put his face in it without harm occurring? If not, protective guarding is needed.