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A P P E N D I X C Project 7 and Project 8 Event Data Dictionary Event Variables the current study. The total will be somewhat greater than the total event N because some events will have more than In the following variables, C-N-I-B is an abbreviation for one trigger. This variable will be automatically generated by crashes, near crashes, incidents, and baseline epochs. the software. Event Identifier (C-N-I-B) Trigger Quantitative Value (C-N-I) Comment: Each event is assigned a file name that is automat- Maximum or minimum value of relevant triggers. For TTC ically generated by the software. triggers, find the closest point at which the two vehicles are still in a path to collision and enter that number. Analyst Identifier (C-N-I-B) Comment: Analysts/data reductionists are identified by their Event Classification (C-N-I-B) log-ins. 00 = Invalid trigger. (In these events, sensor readings were spurious or otherwise not safety-relevant, because of a Trigger Type (C-N-I-B) transient spike or some other anomaly.) 00a = No video. (One or more of the quadrants of video is 00 = Not applicable (baseline epoch). out or not visible. It is not possible to obtain enough infor- 01 = Lateral acceleration. mation to determine the event.) 02 = Longitudinal acceleration. 01 = Baseline driving epoch (selected randomly). (These are 03 = CI button. 1-min periods that are randomly selected from the recorded 04 = Lane deviation/bust. data set. Baseline epochs are described using many of the 05 = Normalized lane position. same variables and data elements used to describe and clas- 06 = Forward time to collision (TTC). sify crashes, near crashes, and incidents. Examples of such 07 = Forward range. variables include ambient weather, roadway type, and driver 08 = Rear TTC. behaviors. The creation of a baseline data set will enable the 09 = Rear range. study to (1) describe and characterize normal driving for the 10 = Side object detection. study sample and (2) infer the increased or decreased risk 11 = Lane change cutoff. associated with various conditions and driver behaviors by 12 = Yaw rate (swerve). comparisons between the control [baseline] data set and the 13 = Automatic collision notification (ACN). incident and near-crash data sets. For example, if 20% of 14 = RF sensor. incidents but only 10% of baseline epochs occurred during 15 = Glare event. rain, one could infer that rain is associated with an increased 16 = Air bag. incident rate and, therefore, increased risk.) 02 = Crash. (This includes any contact with an object [e.g., Comment: These are taken from the 100-Car Study coding, other vehicles, roadside barriers, objects on or off the road- although a number of 100-Car triggers are not being used in way, pedestrians, cyclists, or animals], either moving or 94

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95 fixed, at any speed in which kinetic energy is measurably clear case in which the absence of an avoidance maneuver transferred or dissipated.) or response is inappropriate for the driving circumstances, 03 = Near crash (evasive maneuver). (This classification including speed and sight distance.) includes any circumstance that requires a rapid, evasive 07 = Nonconflict. (This includes any incident that has an maneuver by the subject vehicle or any other vehicle, above-threshold trigger but does not result in a crash, near pedestrian, cyclist, or animal to avoid a crash. A rapid, crash, or crash-relevant conflict as defined above. There is evasive maneuver is defined as steering, braking, accelerat- no abrupt evasive maneuver and no signs of any other ing, or any combination of control inputs that approaches unsafe condition, such as a lane break. Driver errors may the limits of vehicle capabilities. Any event in which the be observed, but they do not result in a traffic conflict. driver swerves off the side of the road and any part of the Examples include hard braking by a driver in the absence truck leaves the pavement is automatically coded a near of a specific crash threat and high lateral acceleration on crash.) curves not resulting in loss of control, lane departure, or 04 = Near crash (no evasive maneuver). (Any circumstance proximity to other vehicles.) that results in extraordinary proximity of the subject vehicle to any other vehicle, pedestrian, cyclist, animal, or fixed Comment: Initial coding step. Invalid triggers and noncon- object in which, because of apparent unawareness on the part flicts result in no further coding. Identification of two types of the driver(s), pedestrians, cyclists, or animals, there is no of near crashes (i.e., evasive maneuver and proximity event) avoidance maneuver or response is coded in this manner. permits later disaggregation if desired. Definitions of each Extraordinary proximity is defined as a clear case in which type of event are given above. the absence of an avoidance maneuver or response is inap- propriate for the driving circumstances, including speed and Date (C-N-I-B) sight distance. TTCs of less than 2.00 s are reviewed to assess whether they qualify as crash-relevant conflicts [or near Comment: Raw data from vehicle. crashes]; TTCs of less than 1.00 s are always coded as crash- relevant conflicts or near crashes.) Day of Week (C-N-I-B) 05 = Crash-relevant conflict (evasive maneuver). (This category includes any circumstance that requires a crash Comment: Raw data from vehicle. avoidance response on the part of the subject vehicle, any other vehicle, pedestrian, cyclist, or animal that is less severe Time (C-N-I-B) than a rapid evasive maneuver [as defined above] but more severe than a normal maneuver. A crash avoidance response Comment: Raw data from vehicle. For C-N-I events, the can include braking, steering, accelerating, or any combina- time of maximum or minimum trigger value is recorded. tion of control inputs. A normal maneuver for the sub- For baseline epochs, the end of the 30-s baseline period is ject vehicle is defined as a control input that falls within the recorded. 99% confidence limit for control inputs for the initial study Format: Integer. data sample. Examples of potential crash-relevant conflicts include hard braking by a driver because of a specific crash Vehicles or Nonmotorists Involved (C-N-I) threat or proximity to other vehicles. Evasive maneuvers resulting in unsafe or illegal maneuvers or situations should 00 = Not applicable (baseline epoch). be included in this category [or as near crashes if more 01 = 1 vehicle (subject vehicle only). severe]. Longitudinal decelerations of -0.35 g or greater are 02 = 2 vehicles. reviewed to assess whether they qualify as crash-relevant 03 = 3 vehicles. conflicts [or near crashes]; those with decelerations of 04 = 4 or more vehicles. -0.50 g or greater are always coded as crash-relevant con- 05 = Subject vehicle + pedestrian. flicts or near crashes.) 06 = Subject vehicle + pedalcyclist. 06 = Crash-relevant conflict (no evasive maneuver). 07 = Subject vehicle + animal. (Included in this classification is any circumstance that 08 = Other. results in proximity of the subject vehicle to any other vehi- cle, pedestrian, cyclist, animal, or fixed object in which, Comment: Events that involve the subject vehicle and an object because of apparent unawareness on the part of the (i.e., struck or potentially struck) are coded 01. For some events driver(s), pedestrians, cyclists, or animals, there is no (e.g., those that involve transient encroachment into an avoidance maneuver or response. Proximity is defined as a oncoming lane), it will be difficult to decide whether the event

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96 should be considered a one- or two-vehicle event. Consider the 08 = Other. event a two-vehicle event if the crash resulting from the incident 09 = Unknown. would probably have involved two vehicles and if either driver's maneuvers were influenced by the presence of the other vehicle Comment: GES A15. (e.g., if Driver/Vehicle 1 [DV1] maneuvered to avoid Vehicle 2 [V2]). Consider the event a one-vehicle event if the presence of Relation to Junction (C-N-I-B) other vehicles presented no immediate threat and had no effect on Driver 1's maneuvers or behaviors. 00 = Nonjunction. 01 = Intersection. 02 = Intersection related. Which Vehicle Is Considered to Be at Fault? 03 = Driveway, alley access, etc. (C-N-I) 03a = Parking lot. 00 = Not applicable (baseline epoch). 04 = Entrance/exit ramp. 01 = Vehicle 1 (subject vehicle). 05 = Rail grade crossing. 02 = Vehicle 2 (other vehicle, pedalcyclists, or animal). 06 = On a bridge. 09 = Unknown. 07 = Crossover related. 08 = Other. Comment: The at-fault vehicle is defined as the vehicle with 09 = Unknown. the assigned critical reason. Comment: GES variable A09. GES instructions for coding this variable will be reviewed to ensure consistency of coding Light Condition (C-N-I-B) approach with GES. 01 = Daylight. 02 = Dark. Construction Zone Related (C-N-I-B) 03 = Dark but lighted. 04 = Dawn. 00 = Not construction zone related (or unknown). 05 = Dusk. 01 = Construction zone (occurred in zone). 09 = Unknown. 02 = Construction zone related (occurred in approach or otherwise related to zone). Comment: General estimate system (GES) A19. Comment: Default code is 0. For the purposes of coding, con- sider any area with multiple traffic cones, barrels, and so forth Weather (Atmospheric Condition) (C-N-I-B) to be a construction zone. 01 = No adverse conditions. 02 = Rain. Traffic Density (C-N-I-B) 03 = Sleet. 04 = Snow. 01 = LOS A: Free flow. (Individual users are virtually 05 = Fog. unaffected by the presence of others in the traffic stream. 06 = Rain and fog. Freedom to select desired speeds and to maneuver within 07 = Sleet and fog. the traffic stream is extremely high. The general level of 08 = Other (smog, smoke, sand or dust, crosswind, hail). comfort and convenience provided to the motorist, pas- 09 = Unknown. senger, or pedestrian is excellent.) 02 = LOS B: Flow with some restrictions. (In the range of Comment: GES A20. stable traffic flow, but the presence of other users in the traffic stream begins to be noticeable. Freedom to select desired speeds is relatively unaffected, but there is a slight Roadway Surface Condition (C-N-I-B) decline in the freedom to maneuver within the traffic stream 01 = Dry. from LOS A because the presence of others in the traffic 02 = Wet. stream begins to affect individual behavior.) 03 = Snow or slush. 03 = LOS C: Stable flow; maneuverability and speed are 04 = Ice. more restricted. (Traffic flow is in the stable range but is 05 = Sand, oil, dirt. beginning to enter the range of flow in which the opera-

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97 tion of individual users becomes significantly affected by Subject Driver Number (C-N-I-B) interactions with others in the traffic stream. The selec- Format: Integer. Automatically generated. tion of speed is now affected by the presence of others, and maneuvering within the traffic stream requires sub- stantial vigilance on the part of the user. The general level Trafficway Flow (C-N-I-B) of comfort and convenience declines noticeably at this 00 = Not physically divided (center two-way left turn lane). level.) 01 = Not physically divided (two-way trafficway). 04 = LOS D: Unstable flow; temporary restrictions substan- 02 = Divided (median strip or barrier). tially slow driver. (This category represents high-density 03 = One-way trafficway. but stable traffic flow. Speed and freedom to maneuver 09 = Unknown. are severely restricted, and the driver or pedestrian experi- ences a generally poor level of comfort and convenience. Comment: GES variable V A11. Coded in relation to subject Small increases in traffic flow generally cause operational vehicle. problems at this level.) 05 = LOS E: Flow is unstable; vehicles are unable to pass, temporary stoppages, etc. (Operating conditions are at or Number of Travel Lanes (C-N-I-B) near the capacity level. All speeds are reduced to a low but 01 = 1. relatively uniform value. Freedom to maneuver within the traffic stream is extremely difficult, and it is generally 02 = 2. accomplished by forcing a vehicle or pedestrian to give 03 = 3. way to accommodate such maneuvers. Comfort and con- 04 = 4. venience levels are extremely poor, and driver or pedes- 05 = 5. trian frustration is generally high. Operations at this level 06 = 6. are usually unstable because small increases in flow or 07 = 7+. minor perturbations within the traffic stream will cause 09 = Unknown. breakdowns.) 06 = LOS F: Forced traffic flow condition with low speeds Comment: GES V A12. Per GES, if road is divided, only lanes and traffic volumes that are below capacity; queues form in in travel direction are counted. If the road is undivided, all particular locations. (This condition exists whenever the lanes are counted. Coded in relation to subject vehicle. Count amount of traffic approaching a point exceeds the amount all contiguous lanes at the time and location of the incident that can traverse the point. Queues form behind such loca- (e.g., include entrance and exit lanes if contiguous). tions. Operations within the queue are characterized by stop-and-go waves and are extremely unstable. Vehicles Truck Pre-Event Speed (C-N-I-B) may progress at reasonable speeds for several hundred feet or more and then be required to stop in a cyclic manner. Format: Integer. LOS F is used to describe operating conditions within the Comment: C-N-I events are coded for the period just before queue, as well as the point of the breakdown. In many the occurrence of the critical event or just before any avoidance cases, operating conditions of vehicles or pedestrians dis- maneuver or both. For example, when braking is involved, charged from the queue may be quite good. Nevertheless, the pre-event speed is the speed just before the beginning of it is the point at which arrival flow exceeds discharge flow, braking. Baseline events are coded for the end of the 30-s base- which causes the queue to form. LOS F is an appropriate line interval. Note that roadway speed limit cannot currently designation for such points.) be determined because most speed limit signs are not legible on 09 = Unknown/unable to determine. the videos. Future efforts (in particular, Phase 2) will consider automated ways to obtain this variable, such as the use of GPS and roadway geographic information systems. Driver/Vehicle 1 Variables Note: DV1 is always the study subject driver/vehicle (e.g., the Roadway Alignment (C-N-I-B) truck driver or truck). 01 = Straight. 02a = Curve right. Subject Vehicle Number (C-N-I-B) 02b = Curve left. Format: Integer. Automatically generated. 09 = Unknown.

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98 Comment: GES V A13, with expansion of curve choices. Alcohol Use (C-N-I-B) Coded in relation to subject vehicle. 00 = None apparent. 01 = Suspected use observed in vehicle without overt effects Roadway Profile (C-N-I-B) on driving. 01 = Level (or unknown). 02 = Suspected use observed in vehicle with overt effects on 02a = Grade up. driving. 02b = Grade down. 03 = Reported by police (applicable only to crashes). 03 = Hillcrest. 04 = Use not observed or reported but suspected based on 04 = Sag. driver behavior. 09 = Unknown. Comment: GES V A14, with expansion of grade choices. Coded in relation to subject vehicle. Comment: Use indicated only if apparent from event review. Note: The remaining DV1 variables are precrash and event Driver Seat Belt Worn? (C-N-I-B) causation variables. Table C.1 lists these variables, indicates sources, and shows the corresponding variable for DV2. 01 = Yes. 02 = No. 09 = Unknown. Vehicle Pre-Event Movement (C-N-I-B) 00 = No driver present. Comment: This issue is of current interest to FMCSA, and its 01 = Going straight. capture would permit comparisons of driver behavior between 02 = Decelerating in traffic lane. drivers wearing and those not wearing seat belts. Judgment is 03 = Accelerating in traffic lane. based on whether a shoulder strap is visible; the lap belt typi- 04 = Starting in traffic lane. cally cannot be seen. 05 = Stopped in traffic lane. 06 = Passing or overtaking another vehicle. Does the Driver Cover the Camera or Is the 07 = Disabled or parked in travel lane. Camera Covered? (C-N-I-B) 08a = Leaving a parking position, moving forward. 00 = Yes. 08b = Leaving a parking position, backing. 01 = No/not observed. 09a = Entering a parking position, moving forward. 02 = Attempts but fails. 09b = Entering a parking position, backing. Table C.1. Coded Precrash and Causation Variables Principal Source(s) Subject Other (e.g., other Vehicle (DV1) Vehicle (DV2) Variable Name databases/studies) Variable No. Variable No. Vehicle pre-event movement GES, LTCCS 27 44 Accident type (scenario role) GES, LTCCS 28 45 Incident types Two recent VTTI studies 29 46 Critical precrash event LTCCS 30 47 Critical reason for the critical event LTCCS 31 48a Attempted avoidance maneuver GES, LTCCS 32 49 Driver vision obscured by GES 34 Not coded Average PERCLOS value (1, 3, 5 minutes) VTTI and other fatigue research 3537 Observer rating of drowsiness (1 minute) Previous VTTI research 38 Potentially distracting driver behaviors GES 39 Driver actions/factors relating to event 100-Car Study 40 50a Applicable functional countermeasures Various 41 51 a Abridged due to inability to observe specific DV2 behaviors and states.

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99 10 = Turning right. Incident Types (C-N-I) 11 = Turning left. 00 = Not applicable (baseline epoch). 12 = Making a U-turn. 01/02 = Aborted lane change. 13 = Backing up (other than parking). 03/04 = Approaches traffic quickly (not used). 14 = Negotiating a curve. 05/06/07/08 = Backing in roadway. 15 = Changing lanes. 09/10 = Clear path for emergency vehicle. 16 = Merging. 11/12 = Conflict between merging and exiting traffic. 17 = Successful avoidance maneuver to a previous critical 13/14 = Conflict with oncoming traffic. event. 15/16 = Exit then re-entrance onto roadway. 98 = Other. 17/18 = Following too closely. 99 = Unknown. 19/20 = Improper lane change. 21/22/23 = Improper passing. Comment: This is Large Truck Crash Causation Survey 24/25 = Improper U-turn. (LTCCS) Variable 4 with expanded choices for 8 and 9. For 26/27 = Lane change without sufficient gap. baseline epochs, the primary movement of the vehicle during 28/29 = Lane drift. the epoch is coded. 30/31 = Late braking for stopped/stopping traffic. 32/33 = Lateral deviation of through vehicle. Accident Type (Scenario Role) (C-N-I) 34/35 = Left turn without clearance. 36/37 = Merge out of turn (before lead vehicle). 00 = Not applicable (baseline epoch). 38/39/40 = Merge without sufficient gap. Other codes (see Table C.2). 41/42 = Obstruction in roadway. 43/44 = Proceeding through red traffic signal. Comment: LTCCS Variable 10 and GES Variable V23. 45/46 = Roadway entrance without clearance. Because this variable includes intent, analysts should proj- 47/48 = Slow speed. ect probable scenario roles for incidents in which outcomes 49/50 = Slow upon passing. are not definite. In other words, if the trigger-related event 51/52/53 = Sudden braking in roadway. had resulted in a crash, what would the crash scenario be? 54/55 = Through traffic does not allow lane change. When specific scenarios cannot be projected, use the spe- 56/57/58 = Through traffic does not allow merge. cific unknown choices (e.g., 5, 10, 16, and 33). Table C.2 59/60 = Turn without sufficient warning. illustrates accident types. 61/62 = Turn/exit from incorrect lane. 63/64 = Wide turn into adjacent lane. Additional clarifications: 65 = Conflict with object/animal/pedalcyclist in roadway. Drive off road codes (e.g., 01 and 06) are used when a 66 = Conflict with object/animal/pedalcyclist on side of road. vehicle has crossed or is projected to cross a roadside delin- 67 = Other single-vehicle event. eation such as a lane edge line (going onto the shoulder or 68/69 = Proximity to turning vehicle. median), a curb, or the edge of the pavement. This includes 99 = Unknown. scenarios that involve parked vehicles and stationary objects Comment: This scenario classification has been used in if those objects are outside the roadway delineation (e.g., on Hanowski, Keisler, and Wierwille (2) and Hanowski, Olson, an unpaved shoulder). Hickman, and Dingus (3). Coding this variable will enable Forward impact codes (e.g., 11 and 12) are used when the comparisons with that study. Diagrams of these scenarios are objects are in the travel lane or when there is no lane edge provided in Table C.3. delineation as described above. Thus, a scenario involving a parked vehicle on the pavement where there is no lane edge delineation is coded 12. Critical Precrash Event for Vehicle 1 (C-N-I) For left-side lane departures into the oncoming traffic 00 = Not applicable (baseline epoch). lane, code 64 or 65 if the lateral encroachment is less than a few feet. Code 50 or 51 only if the lateral encroachment Causes of Vehicle (V1) Loss of Control was sufficient to create a significant risk of a head-on crash. 01 = Blow out or flat tire. Hard-braking events at intersections in the absence of 02 = Stalled engine. a specific crash or crash threat are coded 91 (intersecting 03 = Disabling vehicle failure (e.g., wheel fell off ). straight paths, specifics unknown). (text continues on page 107)

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100 Table C.2. Description of Accident Types (1)

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101 Table C.3. Incident Type Descriptions Incident Type Description Illustration Aborted lane change Driver tries to make a lane change into a lane where there is already a vehicle (driver doesn't see vehicle). The driver has to brake and move back into the original lane. 1 2 Approaches traffic quickly (not used) Driver approaches stopped or slowing traffic too quickly and has to brake hard or suddenly to avoid hitting the lead vehicle. Stationary 3 4 Backing in roadway Driver backs the vehicle while on a roadway in order to maneuver Obstacle around an obstacle ahead on the roadway. 5 6 7 8 Clear path for emergency vehicle Driver is traveling ahead of an emergency vehicle (e.g., ambulance, fire truck) and has to move to the side of the road to let the emer- gency vehicle pass. 9 Emergency Vehicle 10 (continued on next page)

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102 Table C.3. Incident Type Descriptions (continued) Incident Type Description Illustration Conflict between merging or exiting Drivers entering or exiting a roadway, using a shared weaving traffic section, conflict. 11 12 Conflict with oncoming traffic Driver is approaching oncoming traffic (e.g., through an intersection) and has to maneuver back into the correct lane to avoid an 13 oncoming vehicle. 14 Exit then re-entrance onto roadway Driver exits a roadway and then crosses a solid white line to re-enter. 15 16 Following too closely Driver does not allow adequate spacing between his or her vehicle and the lead vehicle (e.g., tailgating). 17 18 Improper lane change Driver makes an improper lane change with regard to another vehicle (e.g., does not use blinker, changes lanes behind another vehicle and then does not let vehicle change lanes, changes lanes across multiple lanes). 19 20

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103 Table C.3. Incident Type Descriptions (continued) Incident Type Description Illustration Improper passing Driver passes another vehicle when it is illegal or unsafe (e.g., pass- ing across a double yellow line or without clearance from oncom- 21 ing traffic). 22 23 Improper U-turn Driver makes a U-turn in the middle of the road (over the double yel- low line) and blocks traffic in the opposite direction. 24 25 Lane change without sufficient gap Driver enters an adjacent lane without allowing adequate space between the driver's vehicle and the vehicle ahead or behind it. 26 27 Lane drift Driver drifts into an adjacent lane without intention to make a lane change. 28 29 Late braking (or steering) for stopped Driver fails to slow in advance for stopped or stopping traffic and or stopping traffic must brake or steer abruptly. Stationary/ Slowing 30 Late Braking 31 (continued on next page)

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104 Table C.3. Incident Type Descriptions (continued) Incident Type Description Illustration Lateral deviation of through vehicle Driver has substantial lateral deviation of a through vehicle. Vehicle may or may not deviate from the lane. 32 33 Left turn without clearance Driver turns left without adequate clearance from either oncoming through traffic or cross traffic from the left. Driver crosses another driver's path while entering an intersecting roadway. 34 35 Merge out of turn (before lead vehicle) Driver merges onto a roadway before the lead vehicle. The lead vehicle must wait for the merged vehicle to pass before it is safe to enter the main highway. 36 37 Merge without sufficient gap Driver merges into traffic without a sufficient gap to either the front or the back of one or more vehicles. 38 39 40 Obstruction in roadway Stationary object blocks through traffic, such as traffic that is backed up or an animal in the roadway. 41 42

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112 Driver 1 Potentially Distracting Driver 13a = Read book, newspaper, etc. Behaviors (C-N-I-B) 13b = Read or look at map. 14 = Talk/sing/"dance" with no indication of passenger. Analysts code up to four behaviors observed during 10 s before 15a = Handle or interact with dispatching, electronic record- the maximum or minimum trigger value or during final 10 s of ing, or navigational device. a 30-s baseline epoch. Code observed behaviors regardless of 15b = Read or look at dispatching, electronic recording, or their apparent relevance to the incident. This is similar to GES navigational device. but significantly modified. If there are more than four behav- 16a = Comb/brush/fix hair. iors, select the ones that occur closest in time to the trigger. 16b = Apply makeup. 16c = Shave. 00 = None observed. 16d = Brush/floss teeth. 01 = Looked but did not see (e.g., driver looked in direction 16e = Bite nails/cuticles. of crash threat but apparently did not recognize threat). 16f = Remove/adjust jewelry. (Not applicable to baseline epochs.) 16g = Remove/insert contact lenses. 02a = Interact with or look at other occupant(s). 16h = Other personal hygiene. 02b = Interact with or look at pet in vehicle. 17 = Look at or handle driver fatigue monitor (DFM). 03a = Look at or for object in vehicle. 18 = Look at or handle data acquisition system (DAS) (e.g., 03b = Reach for object in vehicle (e.g., handheld cell phone, in-vehicle camera). hands-free cell phone, PDA, CB microphone or other com- 19 = Appears inattentive or lost in thought. munications device, or other object). 20 = Other potentially distracting behavior. 04a = Talk or listen to handheld phone. 04b = Talk or listen to hands-free phone. Comment: Similar to GES Variable D7 (driver distracted by), 04c = Talk or listen to CB microphone or other communi- with expansions of many elements to capture direct observa- cations device. tions. All observed behaviors or conditions that occur within 05a = Dial handheld phone. 10 s before the maximum trigger are coded without regard to 05b = Dial hands-free phone. apparent relevance to the conflict. Baseline epochs are coded 05c = Operate PDA (inputting or reading). only for activities that occur within the last 10 s of the 30-s 06 = Adjust instrument panel (e.g., climate control, radio, baseline epoch. Handheld and hands-free phone data are cassette or CD). coded separately to permit comparisons. 07a = Look at left-side mirror/out left-side window. 07b = Look at right-side mirror/out right-side window. 07c = Look back in sleeper berth. Driver 1 Actions, Factors, or Behaviors 07d = Shift gears. Related to the Event (C-N-I) 07e = Look down (e.g., at lap or at something on the floor). Note: Analysts code up to four factors believed to have relevance 08 = Use or reach for other devices. to the occurrence of the incident (e.g., contributing factors). If 09 = Appear drowsy, sleepy, asleep, fatigued. there are more than four factors, the four most important are 10a = Look at previous crash or highway incident. selected. 10b = Look at construction zone signs, barriers, flag- person, etc. 00a = Not applicable (baseline epoch). 10c = Look at outside person. 00b = None coded. 10d = Look at outside animal, object, store, etc. 01 = Apparent excessive speed for conditions or location 10e = Look at undetermined outside event, person, or object. (regardless of speed limit; does not include tailgating unless 11a = Eat with utensil. above speed limit). 11b = Eat without utensil (includes chewing other than gum 02 = Drowsy, sleepy, asleep, fatigued, other reduced alertness. [e.g., toothpick]). 03 = Angry. 11c = Drink from covered container (e.g., with straw). 04 = Other emotional state. 11d = Drink from open container. 05 = Inattentive or distracted. 11e = Chew gum. 06 = Apparent impairment (e.g., drowsy, drunk, 12a = Smoking-related behavior--reaching, lighting, or distracted)--specific type unknown. extinguishing. 07 = Driving slowly (below speed limit or in relation to 12b = Smoking-related behavior--other (e.g., cigarette in other traffic). hand or mouth). 08 = Illegal passing (e.g., across double line).

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113 09 = Passing on right. 47 = Avoiding other vehicle. 10 = Other improper or unsafe passing. 48 = Avoiding animal. 11a = Cutting in, too close in front of other vehicle. 48a = Avoiding object. 11b = Cutting in at safe distance but then decelerating, 49 = Apparent unfamiliarity with roadway. causing conflict. 50 = Apparent unfamiliarity with vehicle (e.g., displays and 12 = Cutting in, too close behind other vehicle. controls). 13 = Making turn from wrong lane (e.g., across lanes). 51 = Use of conventional cruise control (CCC) contributed 14 = Did not see other vehicle during lane change or merge. to late braking (does not imply malfunction of CCC). 15 = Driving in other vehicle's blind zone. 52 = Excessive braking/deceleration creating potential 16 = Aggressive driving, specific, directed menacing actions. hazard. 17 = Aggressive driving, other (reckless driving without 53 = Loss of control on slippery road surface. directed menacing actions). 54 = Loss of control on dry (or unknown) surface. 18 = Wrong side of road, not overtaking (includes partial 55 = Apparent vehicle failure (e.g., brakes). or full drift into oncoming lane). 56 = Other. 19 = Following too closely. 19a = Inadequate evasive action. Comment: This variable was used in the 100-Car Naturalis- 20 = Failed to signal, or improper signal. tic Driving Study, although some new elements have been 21 = Improper turn, wide right turn. added. Also, the coding rule is different; in the 100-Car Study, 22 = Improper turn, cut corner on left turn. analysts coded up to three factors for each driver in descend- 23 = Other improper turning. ing order of judged importance. In the current study, analysts 24 = Improper backing, did not see. code all that apply in no order of importance. Thus, the data 25 = Improper backing, other. from the two studies are not directly comparable. Note that 26 = Improper start from parked position. Element 6 is not relevant to Driver 1, because analysts are not 27 = Disregarded officer or watchman. able to identify impairment type. 28 = Signal violation, apparently did not see signal. 29 = Signal violation, intentionally ran red light. Applicable Countermeasures for DV1 (C-N-I) 30 = Signal violation, tried to beat signal change. 31 = Stop sign violation, apparently did not see stop sign. On the basis of the variables above that relate to the event 32 = Stop sign violation, intentionally ran stop sign at speed. scenario, pre-event actions and states, and event causation, a 33 = Stop sign violation, rolling stop. senior analyst identifies applicable functional countermea- 34 = Other sign (e.g., yield) violation, apparently did not sures. For crashes, an applicable DV1 functional countermea- sure is one that would probably have prevented the crash, see sign. either by preventing the genesis of the unsafe condition or by 35 = Other sign (e.g., yield) violation, intentionally improving driver response to the unsafe condition. Near disregarded. crashes and crash-relevant conflicts are analyzed as if a crash 36 = Other sign violation. had occurred. Table C.4 shows functional countermeasures 37 = Nonsigned crossing violation (e.g., driveway entering and coding rules for them. The coding of functional counter- roadway). measures is based on both algorithmic determination from 38 = Right-of-way error in relation to other vehicle or previous coded variables and analyst judgment. In many cases, person, apparent recognition failure (e.g., did not see other particular accident type, critical reason, or other causation- vehicle). related codes algorithmically determine applicable functional 39 = Right-of-way error in relation to other vehicle or per- countermeasures. Some countermeasure choices, however, son, apparent decision failure (e.g., did see other vehicle are coded based on senior analyst judgment. before action but misjudged gap). 40 = Right-of-way error in relation to other vehicle or per- son, other or unknown cause. Driver/Vehicle 2 Variables 41 = Sudden or improper stopping on roadway. Vehicle/Person 2 Type (C-N-I) 42 = Parking in improper or dangerous location (e.g., shoulder of interstate). 00a = Not applicable (baseline epoch). 43 = Speeding or other unsafe actions in work zone. 00b = Not applicable (single-vehicle event; includes single 44 = Failure to dim headlights. vehicle + object). 45 = Driving without lights or insufficient lights. 01 = Automobile. 46 = Avoiding pedestrian. (text continues on page 117)

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114 Table C.4. Applicable Countermeasures for Vehicle 1 Scenario/Driver Code No. Functional Countermeasure Error Source(s) DV2? Comments 0a Not applicable (baseline epoch) NA Yes 0b No countermeasure applicable to this driver/vehicle (no NA Yes driver error and/or coded to other vehicle only) 0c No obvious or plausible countermeasure applicable to this NA Yes driver/vehicle (e.g., insufficient information because of random occurrence) 0d Not applicable: single-vehicle event Veh/Nonmotorists Yes Never coded for V1 involved = 01, 0507 1 Increase driver alertness (reduce drowsiness) CR = 100 or 107 No Or analyst judgment considering PERCLOS, ORD, driver behavior 2 Improve commercial driver hours-of-service (HOS) compli- No Not coded during Phase I; potential for ance (i.e., reflective of alertness-related incident during Phase II. HOS violation period) 3 Prevent drift lane departures (e.g., caused by fatigue, AT = 01 or 06 Yes No evidence of intention (e.g., lane change). inattention, or misjudgment of lines) 4 Improve vehicle control/stability on curves Trigger Type = 1 Yes Assumes potential rollover or other LOC event; no triggers for V2. And PEM = 14 And AT = 02, 07, 46, 47, or 50 5 Improve vehicle control/stability on slippery road surfaces Road surface = 25 Yes And CPE = 05 6 Improve vehicle control/stability during braking CPE = 09 Yes Or Avoidance maneu- ver = 3 7 Improve vehicle control/stability during evasive steering CPE = 10 Yes Or Avoidance maneu- ver = 69 with LOC 8 Increase driver attention to forward visual scene (e.g., Analyst judgment, No eyes on road) considering poten- tial distractions coded (V39) and CR (e.g., 110119, 140) 9 Increase/improve driver use of mirrors or provide better AT = 46, 47, 70, 73, No information from mirrors (or from other indirect visibility 76, 78, or others systems) TBD and Vision Obscured = 12 or 16 10 Improve general driver situation awareness and/or Analyst judgment No Not coded if 1 and/or 8 are coded. proactive/defensive driving

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115 Table C.4. Applicable Countermeasures for Vehicle 1 (continued) Scenario/Driver Code No. Functional Countermeasure Error Source(s) DV2? Comments 12 Reduce road/highway travel speed CR = 120 Yes Includes all road configurations and thus is inclusive of 1416 but does not Or Driver behavior = include all speeds above speed limit; 1, 43 must be significant factor. 13 Reduce speed on downgrades CR = 120 and No Profile = 2b or Driver B = 1, 43 and Profile = 2b 14 Reduce speed on curves or turns CR = 120 and No Alignment = 2a, 2b Or Driver B = 1, 43 and Alignment = 2a, 2b 15 Reduce speed at or on exits (including ramps) CR = 120 and No Profile = 2b or Driver B = 1, 43 and Profile = 2b 16 Limit top speed to 70 mph (except on downgrades) Prevented speed No greater than 70 mph; analyst judgment Evidence: CR = 120; Driver A/F/B = 1 17 Increase driver recognition/appreciation of specific high- AT = 11, 20 Yes way crash threats: stopped vehicle(s) in lane ahead And CR = 107119 traveling in same direction 18 Increase driver recognition/appreciation of specific high- AT = 24, 28 Yes way crash threats: moving/decelerating vehicle(s) in lane And CR = 107119 ahead traveling in same direction 19 Increase driver recognition/appreciation of specific AT = 47 Yes highway crash threats: vehicle in left adjacent lane on And CR = 107119 highway 20 Increase driver recognition/appreciation of specific AT = 46 Yes highway crash threats: vehicle in right adjacent lane on And CR = 107114 highway 21 Increase driver recognition/appreciation of specific high- AT = 47, 78 Yes way crash threats: vehicle in left adjacent lane during And PEM = 16 merging maneuver And CR = 107119 22 Increase driver recognition/appreciation of specific high- AT = 46, 76 Yes way crash threats: vehicle in right adjacent lane during And PEM = 16 merging maneuver And CR = 107119 23 Increase driver recognition of crossing or oncoming traffic AT = 76, 78, 80, Yes at intersections 8291 And CR = 107119 24 Improve driver gap judgment relating to crossing or AT = 76, 78, 80, Yes oncoming traffic at intersections 8291 And CR = 122 (continued on next page)

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116 Table C.4. Applicable Countermeasures for Vehicle 1 (continued) Scenario/Driver Code No. Functional Countermeasure Error Source(s) DV2? Comments 25 Improve driver response execution of crossing or turning AT = 76, 78, 80, Yes maneuver at intersections (performance failure) 8291 And CR = 141199 26 Improve driver recognition, gap judgment, or response AT = 76, 78, 80, Yes execution at intersection (specific cause not determined) 8291 And CR = 140 or 199 27 Improve driver compliance with intersection traffic signal Driver A/F/B = 2830 Yes (e.g., red light) controls (includes both intentional and unintentional intersection control violations) 28 Improve driver compliance with intersection traffic sign Driver A/F/B = 3133 Yes (e.g., stop or yield sign) controls (includes both inten- tional and unintentional intersection control violations) 29 Increase forward headway during vehicle following AT = 24, 28 Yes Applies to tailgating scenarios, not rapid closing scenarios. And CR = 123 30 Improve driver night vision in forward field Light = 2, 3 Yes CM would provide earlier driver recogni- tion of distant object (e.g., pedestrian And AT = 114, 20, walking in roadway) 34, 36, 38, 40 And analyst judgment 32 Provide warning to prevent rear encroachment or tailgat- AT = 21, 22, 23, 25, Yes Reciprocal relation between 17 and 18 ing by other vehicle (i.e., this vehicle is lead vehicle, 26, 27, 29, 30, 31 and 32 (i.e., if one vehicle is coded 17 other vehicle is following) or 18, other vehicle is coded 32). 33 Provide advisory to driver regarding reduced road-tire friction Roadway surface No (i.e., associated with slippery roads) condition = 25 And LOC And analyst judgment 34 Prevent vehicle mechanical failure (e.g., brakes, steering, CR = 200209, 298, Yes Probably undercounted in instrumented or tire blowout) 299 vehicle studies. 35 Other, specify Analyst judgment Yes When possible, analyst will specify asso- ciated precrash/causation algorithm and add to list of CMs. 36 Prevent splash and spray from this vehicle affecting other AT = 25, 26, 3541, Yes vehicle(s) 4547 And analyst judgment And Roadway surface condition = 2, 3 37 Improve driver recognition/gap judgment relating to PEM = 06 Yes oncoming vehicle during passing maneuver And AT = 50 or 64 And CR = 110119, 120122, or 128140 38 Prevent animals from crossing roadways Vehicle/Person 2 No Applicable to all animal-related events. Type = 13 or 14

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117 Table C.4. Applicable Countermeasures for Vehicle 1 (continued) Scenario/Driver Code No. Functional Countermeasure Error Source(s) DV2? Comments 39 Navigation system/routing aid Driver A/F/B = 49 No 40 Aid to vertical clearance estimation Object = overhanging No Used when truck hits or has the potential object to hit overhanging object (e.g., tree limb). 98 Driver error and/or vehicle failure apparent for this vehicle Vehicle has CR but Yes Not coded if other CMs coded. but countermeasure(s) to address it unknown no other CM specified 99 Unknown Yes Not coded if other CMs coded. Key: AT = accident type; CR = critical reason; CM = countermeasure; PEM = pre-event movement; CPE = critical precrash event; A = actions; B = behaviors; F = factors; TBD = to be determined; LOC = loss of control. (continued from page 113) Vehicle 2 Pre-Event Movement (C-N-I) 02 = Van (minivan or standard van). 00 = No driver present. 03 = Pickup truck. 00a = Not applicable (single-vehicle event). 03a = SUV (includes Jeep). 01 = Going straight. 04 = Bus (transit or motor coach). 02 = Decelerating in traffic lane. 05 = School bus. 03 = Accelerating in traffic lane. 06 = Single-unit straight truck (includes panel truck, 04 = Starting in traffic lane. U-Haul truck). 05 = Stopped in traffic lane. 07 = Tractor-trailer. 06 = Passing or overtaking another vehicle. 08 = Motorcycle or moped. 07 = Disabled or parked in travel lane. 09 = Emergency vehicle (police, fire, EMS; in service) 08a = Leaving a parking position, moving forward. 10 = Vehicle pulling trailer (other than tractor-trailer). 08b = Leaving a parking position, backing. 11 = Other vehicle type. 09a = Entering a parking position, moving forward. 12 = Pedestrian. 09b = Entering a parking position, backing. 13 = Pedalcyclist. 10 = Turning right. 14 = Deer. 11 = Turning left. 15 = Other animal. 12 = Making a U-turn. 99 = Unknown vehicle type. 13 = Backing up (other than parking). 14 = Negotiating a curve. Comment: Highly abridged version of GES V5, body type. If 15 = Changing lanes. Driver/Vehicle 2 is a pedestrian, cyclist, animal, or object, 16 = Merging. most other DV 1 file variables are coded not applicable. 17 = Successful avoidance maneuver to a previous critical event. 98 = Other. Vehicle 2 Position (in Relation to V1) (C-N-I) 99 = Unknown. 00 = Not applicable (baseline epoch). 00a = Not applicable (single-vehicle event). Front K = Top of vehicle. J A B Comment: The vehicle in Figure C.2 represents the DV1 (the I C truck). The relative position of Vehicle 2 (in relation to Vehi- cle 1) is coded for the time in which the critical event occurs; H D that is, the event creating the crash risk. Vehicles in the adja- cent left lane are coded J, I, H, or G, depending on their posi- tion. Vehicles in the adjacent right lane are coded B, C, D, or G F E E, depending on their position. Baseline epochs are coded 0. Rear Figure C.2. Vehicle diagram.

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118 Comment: This is LTCCS Variable 4 with expanded choices parisons with that study. See Variable 29 for diagrams of these for 8 and 9. For baseline epochs, the primary movement of scenarios. the vehicle during the epoch is coded. Vehicle 2 Critical Precrash Event (C-N-I) Vehicle 2 Accident Type (Scenario Role) (C-N-I) 00 = Not applicable (baseline epoch). 00 = Not applicable (baseline epoch). 00a = Not applicable (single-vehicle event). 00a = Not applicable (single-vehicle event). This vehicle (V2) loss of control because of Other Codes: See diagram shown earlier for Variable 28. 01 = Blow out or flat tire. 02 = Stalled engine. Vehicle 2 Incident Type (C-N-I) 03 = Disabling vehicle failure (e.g., wheel fell off). 00a = Not applicable (baseline epoch). 04 = Nondisabling vehicle problem (e.g., hood flew up). 00b = Not applicable (single-vehicle event; includes those 05 = Poor road conditions (wet road, puddle, pothole, ice, etc.). with pedestrian or animal). 06 = Traveling too fast for conditions. 01/02 = Aborted lane change. 07 = Jackknife event. 03/04 = Approaches traffic quickly. 08 = Cargo shift. 05/06/07/08 = Backing in roadway. 09 = Braking. 09/10 = Clear path for emergency vehicle. 10 = Steering. 11/12 = Conflict between merging and existing traffic. 18 = Other cause of control loss. 13/14 = Conflict with oncoming traffic. 19 = Unknown cause of control loss. 15/16 = Exit then re-entrance onto roadway. 17/18 = Following too closely. This vehicle (V1) is traveling 19/20/21 = Improper lane change. 22/23 = Improper passing. 20 = Toward or over the lane line on left side of travel lane. 24/25 = Improper U-turn. 21 = Toward or over the lane line on right side of travel lane. 26/27 = Lane change without sufficient gap. 22 = Toward or off the edge of the road on the left side. 28/29 = Lane drift. 23 = Toward or off the edge of the road on the right side. 30/31 = Late braking for stopped/stopping traffic. 24 = End departure. 32/33 = Lateral deviation of through vehicle. 25 = Turning left at intersection. 34/35 = Left turn without clearance. 26 = Turning right at intersection. 36/37 = Merge out of turn (before lead vehicle). 27 = Crossing over (passing through) intersection. 38/39/40 = Merge without sufficient gap. 28 = This vehicle decelerating. 41/42 = Obstruction in roadway. 29 = Unknown travel direction. 43/44 = Proceeding through red traffic signal. 45/46 = Roadway entrance without clearance. Other motor vehicle (V2) in lane 47/48 = Slow speed. 49/50 = Slow upon passing. 50 = Other vehicle stopped. 51/52/53 = Sudden braking in roadway. 51 = Traveling in same direction with lower steady speed. 54/55 = Through traffic does not allow lane change. 52 = Traveling in same direction while decelerating. 56/57/58 = Through traffic does not allow merge. 53 = Traveling in same direction with higher speed. 59/60 = Turn without sufficient warning. 54 = Traveling in opposite direction. 61/62 = Turn/exit from incorrect lane. 55 = In crossover. 63/64 = Wide turn into adjacent lane. 56 = Backing. 68/69 = Proximity to turning vehicle. 59 = Unknown travel direction of other motor vehicle in lane. 99 = Unknown. Other motor vehicle (V2) encroaching into lane Comment: This scenario classification has been used in Hanowski, Keisler, and Wierwille (2) and Hanowski, Olson, 60 = From adjacent lane (same direction), toward or over Hickman, and Dingus (3). Coding this variable enables com- left lane line.

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119 61 = From adjacent lane (same direction), toward or over Driver-Related Factor: Critical Nonperformance Errors right lane line. 100 = Sleep (i.e., actually asleep). 62 = From opposite direction, toward or over left lane line. 101 = Heart attack or other physical impairment of the 63 = From opposite direction, toward or over right lane line. 64 = From parking lane. ability to act. 107 = Drowsiness, fatigue, or other reduced alertness (not 65 = From crossing street, turning into same direction. 66 = From crossing street, across path. asleep). 108 = Other critical nonperformance. 67 = From crossing street, turning into opposite direction. 68 = From crossing street, intended path not known. 109 = Apparent critical nonperformance (includes any 70 = From driveway, turning into same direction. apparent driver impairment). 71 = From driveway, across path. 72 = From driveway, turning into opposite direction. Driver-Related Factor: Recognition Errors 73 = From driveway, intended path not known. 74 = From entrance to limited-access highway. 110 = Inattention (i.e., daydreaming). 78 = Encroachment by other vehicle, details unknown. 111 = Internal distraction. 112 = External distraction. Pedestrian, pedalcyclist, or other nonmotorist 113 = Inadequate surveillance (e.g., failed to look, looked but did not see). 80 = Pedestrian in roadway. 118 = Other recognition error. 81 = Pedestrian approaching roadway. 119 = Apparent recognition error. 82 = Pedestrian, unknown location. 83 = Pedalcyclist or other nonmotorist in roadway. Driver-Related Factor: Decision Errors 84 = Pedalcyclist or other nonmotorist approaching roadway. 120 = Too fast for conditions (e.g., for safe vehicle control 85 = Pedalcyclist or other nonmotorist, unknown location. or to be able to respond to unexpected actions of other road users). Object or animal 121 = Too slow for traffic stream. 122 = Misjudgment of gap or other's speed. 87 = Animal in roadway. 123 = Following too closely to respond to unexpected actions 88 = Animal approaching roadway. (proximity for 2 or more seconds). 89 = Animal, unknown location. 124 = False assumption of other road user's actions. 90 = Object in roadway. 125 = Illegal maneuver. 91 = Object approaching roadway. 125a = Apparently intentional sign/signal violation. 92 = Object, unknown location. 125b = Illegal U-turn. 125c = Other illegal maneuver. Other 126 = Failure to turn on headlamps. 127 = Inadequate evasive action (e.g., braking only instead 93 = This vehicle not involved in first harmful event. of braking and steering; releasing accelerator only instead 98 = Other critical precrash event. of braking). 99 = Unknown. 128a = Aggressive driving behavior: intimidation. (Any Comment: This is LTCCS Variable 5. Per discussion with behavior emitted by a driver while driving that is intended Ralph Craft of FMCSA, this variable is coded for both vehi- to cause physical or psychological harm to another cles in a two-vehicle incident. However, the critical reason person.) (see below) is coded for only one vehicle. In the list above, 128b = Aggressive driving behavior: wanton, neglectful, or note addition of 09 = loss of control caused by braking and reckless behavior. (Excessive risky driving behaviors per- 10 = loss of control caused by steering. formed without intent to harm others, such as weaving through traffic, maneuvering without signaling, running red lights, frequent lane changing, and tailgating.) DV2 Critical Reason for Critical Event (C-N-I) 138 = Other decision error. 000a = Not applicable (baseline epoch). 139 = Apparent, unknown decision error. 000b = Not applicable (single-vehicle event). 140 = Apparent recognition or decision error (unknown 000c = Critical reason not coded to this vehicle. which).

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120 Driver-Related Factor: Performance Errors 538 = Other sudden change in ambience. 999 = Unknown reason for critical event. 141 = Panic/freezing. 142 = Overcompensation. Comment: LTCCS Variable 6, with revisions that reflect lack 143 = Poor directional control (e.g., failure to control vehicle of information about Driver 2. Many critical reason elements with skill ordinarily expected). available for DV1 are not allowed for DV2, because they 148 = Other performance error. require observation of precrash driver behavior. The remain- 149 = Apparent performance error. ing elements for DV2 are either maneuvers or conditions vis- 199 = Type of driver error unknown. ible from outside the vehicle (e.g., most of the decision error choices) or reasonable general inferences (e.g., codes 109, Vehicle-Related Factors 119, 139, 140, 149). 200 = Tires/wheels failed. 201 = Brakes failed. Attempted Avoidance Maneuver (C-N-I) 202 = Steering failed. 203 = Cargo shifted. 00 = No driver present. 204 = Trailer attachment failed. 00a = Not applicable (baseline epoch). 205 = Suspension failed. 00b = Not applicable (single-vehicle event). 206 = Lights failed. 01 = No avoidance maneuver. 207 = Vehicle-related vision obstructions. 02 = Braking (no lockup or lockup unknown). 208 = Body, doors, hood failed. 03 = Braking (lockup). 209 = Jackknifed. 04 = Braking (lockup unknown). 298 = Apparent other vehicle failure. 05 = Releasing brakes. 299 = Unknown vehicle failure. 06 = Steered to left. 07 = Steered to right. 08 = Braked and steered to left. Environment-Related Factor: Highway 08a = Braked and steered to left (no lockup or lockup 500 = Signs/signals missing. unknown). 501 = Signs/signals erroneous/defective. 08b = Braked and steered to left (lockup). 502 = Signs/signals inadequate. 09 = Braked and steered to right. 503 = View obstructed by roadway design. 09a = Braked and steered to right (no lockup or lockup 504 = View obstructed by other vehicles in crash circum- unknown). stance. 09b = Braked and steered to right (lockup). 505 = Road design, roadway geometry (e.g., ramp curvature). 10 = Accelerated. 506 = Road design, sight distance. 11 = Accelerated and steered to left. 507 = Road design, other. 12 = Accelerated and steered to right. 508 = Maintenance problems (potholes, deteriorated road 98 = Other actions. edges, etc.). 99 = Unknown if driver attempted any corrective action. 509 = Slick roads (low-friction road surface caused by ice, loose debris, any other cause). Comment: LTCCS Variable 7 and GES V27, corrective action 518 = Other highway-related condition. attempted. The released gas pedal elements available for DV1 are not available for DV2, because they would not be observ- able from outside the vehicle. Environment-Related Factor: Weather 521 = Rain, snow. (Note: Code loss-of-control as 509.) Driver Behavior: Driver 2 Actions or Factors 522 = Fog. Relating to Event (C-N-I) 523 = Wind gust. 528 = Other weather-related condition. Note: Analysts code up to four factors believed to have relevance to the occurrence of the incident (e.g., contributing factors). If there are more than four, the four most important are selected. Environment-Related Factor: Other 530 = Glare. 00a = Not applicable (baseline epoch). 531 = Blowing debris. 00b = Not applicable (single-vehicle event). 532 = Animal in roadway (no driver error). 00 = None coded.

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121 01 = Apparent excessive speed for conditions or location 42 = Parking in improper or dangerous location (e.g., shoul- (regardless of speed limit; does not include tailgating unless der of interstate). above speed limit). 43 = Speeding or other unsafe actions in work zone. 02 = Drowsy, sleepy, asleep, fatigued, other reduced alertness. 44 = Failure to dim headlights. 03 = Angry. 45 = Driving without lights or insufficient lights. 04 = Other emotional state. 46 = Avoiding pedestrian. 05 = Alert but inattentive or distracted. 47 = Avoiding other vehicle. 06a = Vehicle drift or slow weave consistent with possible 48 = Avoiding animal. drowsy/distracted driving. 48a = Avoiding object. 06b = Erratic steering, weaving, lane break, or other vehicle 49 = Apparent unfamiliarity with roadway. motion consistent with possible alcohol-impaired driving. 50 = Apparent unfamiliarity with vehicle (e.g., displays and 07 = Driving slowly (below speed limit or in relation to controls). other traffic). 51 = Use of cruise control contributed to late braking. 08 = Illegal passing (e.g., across double line). 52 = Excessive braking/deceleration, creating potential 09 = Passing on right. hazard. 10 = Other improper or unsafe passing. 53 = Loss of control on slippery road surface. 11a = Cutting in, too close in front of other vehicle. 54 = Loss of control on dry (or unknown) surface. 11b = Cutting in at safe distance but then decelerating, 55 = Apparent vehicle failure (e.g., brakes). causing conflict. 56 = Other. 12 = Cutting in, too close behind other vehicle. 57 = Unknown. 13 = Making turn from wrong lane (e.g., across lanes). 14 = Did not see other vehicle during lane change or merge. Comment: Parallel variable to 40 (see Table C.1). Note, how- 15 = Driving in other vehicle's blind zone. ever, that a number of element choices relating to specific driver 16 = Aggressive driving, specific, directed menacing actions. behaviors or impairments are disallowed because these are not 17 = Aggressive driving, other (reckless driving without observable for Driver 2. Also, for signal, sign, and right-of-way directed menacing actions). violations, analysts code the violation but do not attempt to 18 = Wrong side of road, not overtaking (includes partial ascertain whether the violation was intentional or caused by or full drift into oncoming lane). recognition failure. Thus, several elements are not used. As 19 = Following too closely. noted under 40, this variable was used in the 100-Car Natural- 19a = Inadequate evasive action. istic Driving Study, although some new elements have been 20 = Failed to signal, or improper signal. added. Also, the coding rule is different; in the 100-Car Study, 21 = Improper turn, wide right turn. analysts coded up to three factors for each driver in descend- 22 = Improper turn, cut corner on left turn. ing order of judged importance. In the current study, analysts 23 = Other improper turning. code all that apply in no order of importance. Thus, the data 24 = Improper backing, (apparently) did not see. from the two studies are not directly comparable. 25 = Improper backing, other. 26 = Improper start from parked position. Applicable Functional Countermeasures 27 = Disregarded officer or watchman. for DV2 (C-N-I) 28 = Signal violation. 29 = Not used. On the basis of the variables above that relate to the event 30 = Signal violation, tried to beat signal change. scenario, pre-event actions and states, and event causation, 31 = Stop sign violation. senior analysts identify applicable functional countermea- 32 = Not used. sures. For crashes, an applicable DV2 functional countermea- 33 = Stop sign violation, rolling stop. sure is one that would probably have prevented the crash 34 = Other sign (e.g., yield) violation. by either preventing the genesis of the unsafe condition or 35 = Not used. improving driver response to the unsafe condition. Near 36 = Other sign violation. crashes and crash-relevant conflicts are analyzed as if a crash 37 = Nonsigned crossing violation (e.g., driveway entering had occurred. Variable 41 (see Table C.1) provides a table of roadway). functional countermeasures and shows coding rules for them. 38 = Right-of-way error in relation to other vehicle or person. The coding of functional countermeasures is based on both 39 = Not used. algorithmic determination from previous coded variables 40 = Not used. and analyst judgment. In many cases, particular accident type, 41 = Sudden or improper stopping on roadway. critical reason, or other causation-related codes algorithmically

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122 determine applicable functional countermeasures. Some affecting coding, and coding issues that arose. Ordinarily this countermeasure choices, however, are coded based on senior will not contain information that is captured by the coded analyst judgment. Most potential functional countermeasures variables. are coded for DV2, but some are not, because little informa- tion is available to analysts on the specific Driver 2 behaviors References and states. 1. Thiriez, K., G. Radja, and G. Toth. Large Truck Crash Causation Study: Interim Report. Report DOT HS 809 527. NHTSA, 2002. General Variables 2. R. J. Hanowski, A. S. Keisler, and W. W. Wierwille. Light Vehicle- Heavy Vehicle Interactions: A Preliminary Assessment Using Critical Event Comments (C-N-I-B) Incident Analysis. Report FMCSA-RT-04-004. FMCSA, 2004. 3. R. J. Hanowski, R. L. Olson, J. S. Hickman, and T. A. Dingus. The Comment: This text variable will permit analysts to provide 100-Car Naturalistic Driving Study: A Descriptive Analysis of Light Vehi- any comments on the event, including information not cap- cle-Heavy Vehicle Interactions from Light Vehicle Driver's Perspective. tured by data variables, assumptions made about the event Virginia Tech Transportation Institute, Blacksburg, Va., 2004.