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T.C. 550.001 Applicability of Chapter
(Exception to Applicability Rule 542.001)

Provision of Chapter 550 apply to places other than highway; i.e. road owned and controlled by a water control district, private access way or parking area provided for client or patron by a business (no fee charged), public place.

T.C. 550.021/550.023 Failure to Stop and Render Aid (F.S.R.A.)

Accident involving a vehicle that results in death or injury to a person.
Involving accident resulting in death of or serious bodily injury.
3rd Degree Felony.
Involving accident resulting in injury.
1 to 5 years in imprisonment.
fines not to exceed 5,000 dollars.
Both the fine and imprisonment or confinement.
3rd Degree Felony or Class B

T.C. 550.022/023 Failure to Give Information
Hit and Run (H&R), Fleeing the Scene

Accident involving an attended vehicle that results in damage.
Requires immediate stop or immediate return, reasonable time, to complete requirement of 550.023.
Class B if Damage to all vehicles involved is $200.00 or more.
Class C if Damage to all vehicles involved is less than $200.00.
Requires to the removal of each vehicle involved in an accident occuring on a main lane, ramp, shoulder, median, or adjacent area of a freeway in a metropolitan area and each vehicle can be normally and safely driven.
Class C

T.C. Duty to Give Information and Render Aid

Specifies information requirements for 550.021 and 550.022 and aid requirements for 550.021.
Information Required:
1. Name
2. Address
3. Registration number (license number)
4. liability insurer (method of financial responsibility)
5. and if requested and available, show drivers license
Aid Required if injuries necessitate treatment by physician or hospital and if necessity of treatment is apparent. (Observed or Implied)

T.C. 550.024 Duty Strikes Unattended Vehicle

Requires immediate stop and location of owner or person in charge of unattended vehicle. If not able to locate owner or person in charge of unattended vehicle, leave a written notice with a statement of the circumstances of the collision.
Information requirements:
1. Name
2. Address
3. Owner of vehicle beingd driven
Class B if damages to all vehicles involved is $200.00 or more.
Class C if damages to all vehicles involved is less than $200.00.

T.C. Duty on Striking Fixture or Highway Landscaping

Requires a reasonable attempt to locate and notify the owner or person in charge of the property.
Information required:
1. Name
2. Address
3. Registration number (license number)
4. If requested and available show driver's license.
Make a report of accident in results in death, injury or damage to any person's property to an apparent extent of $1000.00 or more.
Class B if damages to all fixtures and landscaping is $200.00 or more.
Class C if damages to all fixtures and landscaping is less than $200.00.

T.C. 550.026 Immediate Report of Accident

Requires operators of vehicles involved in an accident resulting in death, injury to a person, or damage to a vehicle to the extent that it cannot be normally and safely driven (blocking traffic, traffic hazard, public safety issue) to immediately notify.
The local police department; the sheriff's office; or the nearest office to the department of public safety.

T.C. 550.041 Investigation by Peace Officer

Authority of a peace officer to investigate accidents resulting in death or injuries to a person or property damage to an apparent extent of $1000.00 and to file justifiable charges. (Not an authority to arrest, only to file at-large charges.)

T.C. 550.061 Operators Accident Report
C.R. 2
Blue Form

The operator of a vehicle inolved in an accident shall make a written report of the accident if the accident is not investigated by a law enforcement officer and the accident resulted in injury to or the death of a person or damage to the property of any one person to an apparent extent of $1000.00 or more.
Must be filled out with the department not later than the 10th day after the date of the accident.

T.C. 550.062 Officer's Accident Report
C.R. 3

Requirement to report an accident resulting in death or injury to a person, or damage to the property of any one person to an apparent extent of $1000.00 or more to the Texas Department of Transportation may be complied with by filing a C.R. 2 directly to the department (each driver involved) or by reporting the accident to a law enforcement agency who in turn is required to report accident by filing a C.R. 3 to the Texas Department of Transporation. Time limit for reporting accident in either method is 10 days.

T.C. 550.063 Report on Appropriate Form

Requires individuals to report accidents on appropriate form or forms and disclose all required information.

T.C. 550.064 Accident Reports

Information requirements for accident report forms prepared by the Texas Department of Transportation.
C.R. 3 must be required sufficiently detailed information to disclose the cause and conditions of and the persons and vehicles involved in an accident.
C.R. 2 and C.R. 3 must require sufficently detailed information to disclose the cause and conditions of and the persons and vehicles involved in an accident.
C.R. 3 must include a way to designate and identify peace officers, firefighters, and emergency medical service employees who during emergency is involved in an accident while performing duties.
C.R. 3 must include a statement as to the nature of emergency.
C.R. 3 must include a way to designate whether an individual involved in an accident wants to be contacted by a person seeking employement as a professional.

Human Factors

The conditions of the driver or drivers; pedestrian or pedestrians; pedacyclist or pedacyclists; etc., to include physical, mental, emotional conditions which could contribute to the causes of crashes.
Determine by face to face observations of physical characteristics, witness statements, evidence of intoxicants, field sobriety tests, etc.

Vehicle Factors

The condition of the vehicles involved prior to crash, including but not limited to: steering components; suspension; tires; brakes/braking system; wipers; lights; loading of vehicle; safety restraints; visors; obstructions to visbility; loose objects inside vehicle.
Determine by cursory inspection of the vehicle; statements of the driver/passengers; witness statements; mechanical inspection by qualified personnel.

Environmental Factors

Weather and light conditions existing at time of crash. Type of locality (surroundings) in the vacinity of crash, i.e. rural versus urban.
Determine by observation; driver and witness statements; U.S. Weather Bureau.

Traffic Control Factors

Type of traffic control present or absent at crash scene. Traffic control visible/not visible, operating/not operating at time of crash.
Determine by observations; driver and witness statements; Traffic Control records/logs; Traffic Engineers.

Roadway Factors

Roadway surface and topographical features. Topographical features includes curves, grade and super elevation. Road surface includes roadway type and surface conditions.
Determine by observation; grade and super elevation measurements; measure radius of curve; genral description of surface type and condition (published drag factor chart); actual surface testing. Testing includes, but not limited to:
1. Skid test with actual vehicle involved in accident***
(***generally not in law enforcement)
2. Skid test with similiar vehicle/similar tires.
3. Drag sled

Conducting the Skid Test

1. Run the test on the same surface as the crash vehicle skids.
2. Run the test in the same direction as the crash vehicle skids.
3. Use Radar to verify the speed of the test vehicle, if possible. If not, use a vehicle with a "certified" and "verified" speedometer. Conduct the test at a speed of 30 to 45 miles per hour.
4. Procedures.

Conducting the Skid Test
#4 Procedures
A.

4. Procedures:
A. Drive the test vehicle two or three miles per hour above the test speed you select to use. Let off the accelerator and allow the vehicle to coast to the selected speed. When designated speed is reached, jam on the brakes very hard to lock all of the wheels. Continue to apply full braking until the vehicle comes to a complete stop.
Note: If any problems arise during the skid, abort the test by releasing the brakes and regain control of vehicle.

Conducting the Skid Test
#4 Procedures
B.

B. Put the vehicle in "park", turn off the vehicle ignition and exit the vehicle.

Conducting the Skid Test
#4 Procedures
C.

C. Measure all four tire marks if possible. If this is not possible becuase of overlapping, measure the two tire marks. Be sure to include the :"shadow" or impeding skid mark. Use the longest tire mark as the distance skid.

Conducting the Skid Test
#4 Procedures
D. through F.

D. Conduct a minimum of two tests.
E. If the length of the test skids do not agree within ten percent, when conducted at the same test speed, conduct additional test until the results of two test agree.
F. If the tests are not conducted at the same speed, the resulting calculated drag factor must agree with 5 percent.

Nomograph

A chart on with three or more scales are arranged so that a straight line drawn through values on any two will cross the third at a corresponding value; a graphic calculator.

Drag Factor

is a percentage of the pull of gravity. It is the ratio of pounds of horizontal forces that it takes to put a vertical force, weight, in motion.

Grade

is the degree of inclination of the center line area of a roadway as compared with the horizontal. Grade is positive (+) if it rises in a specific direction and negative (-) if it falls. Grade is calculated as the percent of the rise or fall from the horizontal, or level, over a given distance.

Super-Elevation, or Bank

is the grade across a roadway, usually measured from the inside to the outside edges of a roadway. For example, if the bank of a curve, measured from the inside to the outside, had a rise six inches, or 0.50 feet, in a roadway width of 28 feet, the percent bank, super-elevation, would be 1.78 percent or 0.0178.

Methods of Measurement

1. Protractor/Angle Method
(measure angle/convert using tangent)
2. Carpenter's Level and Ruler Method
(measure rise over run)
3. Clipboard and Template Method
(measure grade from template)

Debris

A. Debris can be liquid or solid.
B. Debris can be used to determine P.O.I. at low speed impacts.
C. Debris scatters from the point of origin in a "v" or fan pattern.
D. Debris scatters in the direction of the force.

Tire Marks

A.Skid Marks.
B. Scrub Marks.
C. Off-Set Marks

Skid Marks

1. Vehicle's location on the roadway leading up to the P.O.I.
2. The approximate P.O.I. if there is deviation in the skid marks such as in offset skid marks.

Scrub Marks
(part 1)

1. Results from collision, wheel locked or jammed during collision.
2. Most commonly caused by sideways movement of a vehicle during collision.
3. Beginning of scrub mark is useful in determining the P.O.I.

Scrub Marks
(part 2)

4. If the scrub mark is caused by sideways movement of the vehicle, striation marks may result from the sideways movement of the tire shoulder ribs.
5. If the direction of the scrub is in alignment with the tire, the scrub mark may appear in much of the same manner as a straight skid mark, i.e., when parked or stopped vehicle are rear-ended.

Off-Set Marks

1. Indicate the location of the tire at the P.O.I.
2. Indicate the direction of the applied force that changed the direction of the vehicle.
3. Offset marks most often appear as a scrub mark.

Roadway Marks or Damage

A. Chip.
B. Hole.
C. Gouge.
D. Groove.
E. Scratch.
F. Scrape.

Chip

Is a concave, chip-like cavity in the pavement caused by a metal protrusion. Edges of the cavity may have striations that can be measured and matched to the object that caused the cavity.
Superficial hole.

Hole

Is a round, smooth, walled cavity in the roadway surface and is usually caused by protruding bolts, broken rods, or similar round objects.

Gouge

is a concave, chip-like cavity in the pavement caused by a metal protrusion. Edges of the cavity may have striations that can be measured and matched to the object that caused the cavity. May be deeper at one end than another.

Groove

Is a long, narrow, indentation or furrow cut into the roadway surface, generally caused by a bolt or some similar type of protruding part of the vehicle. A groove may be straight or circular. Straight grooves indicate the direction of travel. Circular grooves indicate that the vehicle was in rotation or spinning. A groove may be deep initially and become shallower towards its end.

Scratch

Individually is a long, narrow, superficial mark on a highway surface. A scratch mark is usually caused by a sliding vehicle part other than a tire. Scratch marks usually are not deep and often appear as a broad band of rough, parallel striations.

Scrape

is a wide superficial mark or a wide, clean gaze mark caused by a sharp or angular edge being passed over the highway surface, i.e., a vehicle part sliding over the roadway.

Damage to Fixed Objects

1. Trees
2. Guard rails
3. Fences
4. Signs
5. Signals
6. Posts/poles
7. Bridges/structures
8. Curbs.
Fixed objects can be on or adjacent to the highway. Some fixed objects may show repeated damage. If is therefore important to examine them for new damage that can be related to the accident under investigation.

Speed Estimates From Skid/Yaw Marks
A. Skid Marks
(4 of 5)

Skid Marks are valuable as evidence and may be used to determine:
1. A vehicle's position relative to the roadway leading up to the point of impact (P.O.I.).
2. The point of impact if offset, scrub, skid marks are present.
3. The path of travel of vehicle before and after impact.
4. The action of the vehicle, i.e., rotation, change of direction, etc.

Speed Estimates From Skid/Yaw Marks
A. Skid Marks
(5A of 5F)

5. The minimum speed of a vehicle at hte commencement of its skid. In order to make such determinations, the following information must be known:
A. The length of the skid mark or marks, use the average length if able to measure each skid mark separately.

Speed Estimates From Skid/Yaw Marks
A. Skid Marks
(5B-D of 5F)

B. Drag Factor
C. Grade and/or super elevation of the roadway. Add or subtract grade/super elevation from the drag factor if the drag factor is determined from a level surface source, i.e. published chart.
D. The number of wheels locked/braking.
Note: Due to the limitations of the nomograph, calculate speed only for 100 percent braking.

Speed Estimates From Skid/Yaw Marks
A. Skid Marks
(5E-F of 5F)

E. The vehicle did not collide with a substantial object before skidding to a stop; i.e., another vehicle, fixed object, etc.
F. The vehicle was not towing a trailer, unless the trailer was equipped with brakes which were applied and locked at approximately the same time as the brakes on the towing vehicle.

Skid Mark Measurements

In measuring the length of the skid marks for speed determination purposes, the following protocol should be followed.
1. Accuracy.
2. Purpose.
3. Recording.
4. Markers.
5. Average Length.
6. Impending/Positive skid Marks.
7. Overlapping skid Marks.
8. Dual wheel skid marks.
9. Gap or intermittent skid marks.
10. Skip skids.
11. Curved Skid Marks.
12. Offset skid marks.
13. Motorcycle Skid Marks.
14. Spin skid marks.
15. Various surface skid marks.

1. Accuracy.

use a measuring device, i.e., tape measure, roller tape, or other accurate measuring device. The pace method of measurement may be used, but only if no other method or device is available.

2. Purpose.

The purpose of measuring a skid mark is to determine the amount of work being done between the locked tire and the road surface. In addition to measuring the length of each skid mark, the investigator should also measure the position of the skid mark or marks relative to the roadway.

3. Recording.

Measurements should be taken to the closest inch or tenth of a foot. When more than one person is involved in taking measurements, tape measure, the investigator recording the measurements should be reading the measurements from the measuring device.

4. Markers.

Use markers, paint, chalk, etc., to show specific positions such as the beginning of an impending skid for photographic purposes. In order to avoid any arguments against the admissibility of the photographs in court, photographs should be taken before any markers are placed at the accident scene. Always photograph a pristine crime or accident scene. If necessary or if the investigator desires, additional photographs may be taken with markers, scales, etc.

5. Average Length.

When possible, measure all the skid marks lengths seperately and then use the average skid mark length to determine the minimum speed. If the skid marks are straight and it appears that the wheels/tires locked-up at approximately the same time, it is permissible to use the longest skid mark for speed determination.

6. Impending/Positive skid Marks.

Include the impending or "shadow" skid mark in the measurement of the skid marks. The impending skid mark results from a braked wheel just prior to complete cessation of rotation. Braking efficiencies are the highest at this point.
Note: Impending skid marks are very similar to marks from vehicles equipped with A.B.S.

7. Overlapping skid Marks.

Measure the total length of overlapping skid marks and then subtract the wheel base of the vehicle. The actual skid distance is the total skid mark length minus the vehicle's wheel base.

8. Dual wheel skid marks.

Two tires on one wheel assembly, dual wheel, will leave two skid marks, however count each dual wheel as one skid mark.

9. Gap or intermittent skid marks.

Gap skid marks appear when sheels are locked, released and relocked through braking action, jab or braking method, leaving gaps between skid marks. The skid or spaces between the skid marks are usually longer than ten feet. (fifteen to 20 feet). Measure each skid mark seperately, including any impeding skid mark, and exclude or discount the spaces. use the sum of the gap skid marks actually measured for the total skid mark length.

10. Skip Skids

Skip Skids marks occur when locked wheels bounce on a roadway. The spaces between the skip skid marks are usually less than five feet. (3 feet). The bouncing of the wheels is usually caused by a wheel striking a hole, bump, or object on the roadway surface. Unloaded or lightly loaded trailers or semi-trailers are particularly susceptible to bouncing also known as "trailer hopping". Measure skip skids marks as one continuous skid mark, including or counting the spaces.

11. Curved skid marks

Measure curved skid marks by allowing the measuring device to follow the path of the skid mark as it curves. Do not confuse a curve skid mark with a yaw mark.

12. Offset skid marks

Measure the entire length of the skid mark, including the offset. If a skid mark is offset because the vehicle changed direction resulting from an impact, measure the length of the lead-in skid mark seperately from the actual offset.

13. Motorcycle skid marks

Measure each skid mark seperately. Check the tires on the motorcycle from the presence of contact patches to determine which tire or tires created the skid mark or marks. Should there be any additional marks, i.e., roadway marks like chips, holes gouges, grooves, scratches, and or scrapes; from the motorcycle sliding on its side, a seperate measurement should be taken of the distance the motorcycle traveled creating the roadway mark.

14. Spin Skid Marks

The length and exact position of each mark should be measured. An average of the skid mark distance or length of the path of travel of the center of mass be used as the skid distance for speed determinations.

15. Various Surface Skid marks

When skid mark or marks traverse different surfaces, measure the skid mark distance for each surface seperately because of the potential of different drag factor values for each surface.

Yaw Marks:
Critical Speed Scuffs
(2 of 3C)

Yaw marks, critical speed scuffs, are valuable as evidence and may be used to determine:
1. The path of travel of a vehicle during the time it was yawing.
2. That the vehicle was traveling too fast to safely negotiate a curve, a swerve to avoid, or a turning maneuver.

Yaw Marks:
Critical Speed Scuffs
(3A of 3C)

3. An estimate of the vehicle's speed. In order to make such an estimate, the following information must be known:
A. The radius of hte path of the center of mass travel. Since it is not possible to measure this radius, the radius of the leading outside tire mark or yaw should be used.
B. Drag Factor.
C. Grade and/or super elevation of the roadway. Add, up, or subtract, down, grade/super elevation from the drag factor determine from a level surface source.

Yaw Mark Measurements

In measuring the radius of a yaw mark for speed determination purposes, the following protocol should be followed:
1. Accuracy.
2. Purpose.
3. Leading Outside yaw/scuff mark.

1. Accuracy

It is necessary to use a straight line measuring device, such a tape measure, to measure the chord and middle ordinate of the yaw mark or curve.

2. Purpose
(1 of 2)

The purpose of measuring a yaw mark, critical speed scuff, is to determine the radius of the path of the center of mass of a vehicle. The actual measurement taken is of the radius of the scuff or yaw marks made by the vehicle.

2 Purpose
(2 or 2)

To adjust for the path of the center of mass travel, subtract half of the width of the vehicle from the raidus of the leading outside scuff/yaw mark. In addition to measuring the radius, the investigator should also measure the position of the yaw mark or marks relative to the roadway.

3. Leading outside yaw/scuff mark

In order to calculate the speed of a vehicle in yaw, a chord and middle ordinate measurements should be taken of the approximate first third of the leading outside yaw/scuff mark. The chord measurement should begin after the rear wheel has tracked outside the front wheel so that there is a least one foot of distance between the marks.

Chord

A chord is a straight line measurement between any two points of an arc or circle, less than the diameter.

Middle ordinate

a middle ordinate is a perpendicular measurement taken from the middle of the chord to the outside of the arc or circle.

Grade

is the degree of inclination of the center line area of a roadway as compared with the horizontal. Grade is positive (+) if it rises in a specific direction and negative (-) if it falls. Grade is calculated as the percent of the rise or fall from the horizontal, or level, over a given distance.

Super-Elevation or Bank

is the degree of inclination (grade) across a roadway, usually measured from the inside to outside edges of a roadway. For example, if the bank or a curve, measured from the inside to the outside, had a rise of six inches, or 0.50 feet, in a roadway width of 28 feet, the percent super-elevation or bank would be 1.78 percent or 0.0178.

Circle

is a figure bounded by a curved line, every part of which is an equal distance from a point called the center.

Circumference

Perimeter, is the length of the curved line which forms the circle, the boundry line.

Radius

is a straight line from the center point of the circle to the circumference..

Diameter

is a straight line that passes through the center point and touches or intersects the circumference in 2 places.

Arc

is a section of the circumference between 2 points

chord

is a straight line that intersects the circle's circumference at 2 points. It cannot be longer than the diameter.

Middle Ordinate

is a straight line measured perpendicular from the chord's midpoint to the circumference of the circle.

Drag Factor

is a percentage of the pull of gravity. It is the ratio of pounds of horizontal force that it takes to put a vertical force, weight, in motion.

Reference Point

is a point from which measurements are made to establish or fix other points.
Reference points may be tangible, permanent, or intangible, temporary.

Tangible Reference Point

includes such permanent things as posts, buildings, bridges, signs, trees, fire hydrants, man-hole covers, roadway damages, i.e., potholes, roadway edge chips, etc., and other permanent conditions or objects.

Intangible Reference Points

include such temporary points as crayon marks placed on the roadway, imaginary or temporarily marked curb extension lines, spray paint marks, or other temprary identification marked, placed, or designated on a surface. An intangible reference point must always be connected to or identified with a permanent reference point.

Coordinate Method

Coordinates are distances measured at right angles from a baseline to an object or point. When the roadway is straight or has only a very slight curve, the edge of the roadway may be used as a baseline. (X; Y coordinate or latitude and longitude.)

Triangulation Method

Triangulation is a method of locating a spot in an area by straight line measurements from two or more reference points, the locations of which are identified for future reference.

Crash (Accident)

is an unintended event or unstabilized situation that produces injury or damage not directly resulting from a cataclysm.

Motor Vehicle Crash (accident)

is a crash involving a motor vehicle in transport, but not involving aircraft or watercraft.

Crash (accident) Investigation

is the thorough examination of all elements contributing to the crash, resulting in a well-founded explanation of the series of events which occurred based upon the factual data.

Chip

is a concave, chip-like cavity in the pavement caused by a metal protrusion. Edges of the cavity may have striation marks that may be measured and matched to the object that caused them.
Superficial hole.

Hole

is a cavity in a roadway surface that is round, dependant of shape of object causing hole, with smooth walls and is usually caused by protruding bolts, broken rods or similar objects.

Gouge

is a concave, cavity in the pavement caused by a metal protrusion. Edges of the cavity may have striations that can be measured and matched to the object that caused the cavity. Maybe deeper at one end than another.

Groove

is a long, narrow indentation or furrow cut into the roadway surface, generally caused by a bolt or some similar type of protruding part of the vehicle. A groove may be straight or circular. Straight grooves indicate the direction of travel. Circular grooves indicate that the vehicle was in rotation or spinning. A groove may be deep initially and become shallower towards the end.

Scrape

is a wide superficial wound or a wide, clean graze mark cause by a sharp or an angular edge being passed over the highway surface.

Scratch

is a long narrow superficial wound on a highway surface

Debris

is a fragment or scattered loose materials strewn on the roadway as the result of a collision, or otherwise falling from a vehicle. May be solid or liquid.

Ruts

a track or depression worn in soft materials such as sand, dirt, mud, etc., by a rotating tire.

Trenches or Furrows

a track or depression worn in soft materials such as sand, dirt, mud, etc., by a skidding or sideslipping tire.

Skip Skids

occurs when a lock wheel bounces on the roadway. The blank spaces between the skid marks are usually less than 5 feet. (3 feet).

Gap Skids

occurs when locked wheeled are released and re-locked through braking action. The blank spaces between the skid marks are usually 10 feet or longer. (15-20 feet)

Skid Marks

are tire marks caused by non-rotating tire/tires; or tire/tires that is not free to rotate. May include tire grinding; pavement grinding; erasing; squeegee marks; smearing of soft material; smearing of bituminous materials; and tire smears as part of the skid marks.

Scuff Marks

are tire marks caused by tire or tires that is rotating and side slipping

Tire marks

are marks caused by tires moving over a surface, general term.

Tire prints

are tire marks caused by a rotating tire or tires traveling over soft material, may be found at the bottom of a rut, or when the rotating tire or tires travel over a wet surface, then over a dry surface leaving an imprint of the tire tread pattern.

Striation Mark

are narrow, parallel scratches on a surface caused by skidding or scuffing tires.

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