Feasibility of Using In-Vehicle Video Data to Explore How to Modify Driver Behavior That Causes Nonrecurring Congestion (2011)

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A P P E N D I X C Project 7 and Project 8 Event Data DictionaryEvent Variables In the following variables, C-N-I-B is an abbreviation for crashes, near crashes, incidents, and baseline epochs. Event Identifier (C-N-I-B) Comment: Each event is assigned a file name that is automat- ically generated by the software. Analyst Identifier (C-N-I-B) Comment: Analysts/data reductionists are identified by their log-ins. Trigger Type (C-N-I-B) • 00 = Not applicable (baseline epoch). • 01 = Lateral acceleration. • 02 = Longitudinal acceleration. • 03 = CI button. • 04 = Lane deviation/bust. • 05 = Normalized lane position. • 06 = Forward time to collision (TTC). • 07 = Forward range. • 08 = Rear TTC. • 09 = Rear range. • 10 = Side object detection. • 11 = Lane change cutoff. • 12 = Yaw rate (swerve). • 13 = Automatic collision notification (ACN). • 14 = RF sensor. • 15 = Glare event. • 16 = Air bag. Comment: These are taken from the 100-Car Study coding, although a number of 100-Car triggers are not being used in94the current study. The total will be somewhat greater than the total event N because some events will have more than one trigger. This variable will be automatically generated by the software. Trigger Quantitative Value (C-N-I) Maximum or minimum value of relevant triggers. For TTC triggers, find the closest point at which the two vehicles are still in a path to collision and enter that number. Event Classification (C-N-I-B) • 00 = Invalid trigger. (In these events, sensor readings were spurious or otherwise not safety-relevant, because of a transient spike or some other anomaly.) • 00a = No video. (One or more of the quadrants of video is out or not visible. It is not possible to obtain enough infor- mation to determine the event.) • 01 = Baseline driving epoch (selected randomly). (These are 1-min periods that are randomly selected from the recorded data set. Baseline epochs are described using many of the same variables and data elements used to describe and clas- sify crashes, near crashes, and incidents. Examples of such variables include ambient weather, roadway type, and driver behaviors. The creation of a baseline data set will enable the study to (1) describe and characterize normal driving for the study sample and (2) infer the increased or decreased risk associated with various conditions and driver behaviors by comparisons between the control [baseline] data set and the incident and near-crash data sets. For example, if 20% of incidents but only 10% of baseline epochs occurred during rain, one could infer that rain is associated with an increased incident rate and, therefore, increased risk.) • 02 = Crash. (This includes any contact with an object [e.g., other vehicles, roadside barriers, objects on or off the road- way, pedestrians, cyclists, or animals], either moving or

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

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

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

98Comment: GES V A13, with expansion of curve choices. Coded in relation to subject vehicle. Roadway Profile (C-N-I-B) • 01 = Level (or unknown). • 02a = Grade up. • 02b = Grade down. • 03 = Hillcrest. • 04 = Sag. Comment: GES V A14, with expansion of grade choices. Coded in relation to subject vehicle. Driver Seat Belt Worn? (C-N-I-B) • 01 = Yes. • 02 = No. • 09 = Unknown. Comment: This issue is of current interest to FMCSA, and its capture would permit comparisons of driver behavior between drivers wearing and those not wearing seat belts. Judgment is based on whether a shoulder strap is visible; the lap belt typi- cally cannot be seen. Does the Driver Cover the Camera or Is the Camera Covered? (C-N-I-B) • 00 = Yes. • 01 = No/not observed. • 02 = Attempts but fails.Alcohol Use (C-N-I-B) • 00 = None apparent. • 01 = Suspected use observed in vehicle without overt effects on driving. • 02 = Suspected use observed in vehicle with overt effects on driving. • 03 = Reported by police (applicable only to crashes). • 04 = Use not observed or reported but suspected based on driver behavior. • 09 = Unknown. Comment: Use indicated only if apparent from event review. Note: The remaining DV1 variables are precrash and event causation variables. Table C.1 lists these variables, indicates sources, and shows the corresponding variable for DV2. Vehicle Pre-Event Movement (C-N-I-B) • 00 = No driver present. • 01 = Going straight. • 02 = Decelerating in traffic lane. • 03 = Accelerating in traffic lane. • 04 = Starting in traffic lane. • 05 = Stopped in traffic lane. • 06 = Passing or overtaking another vehicle. • 07 = Disabled or parked in travel lane. • 08a = Leaving a parking position, moving forward. • 08b = Leaving a parking position, backing. • 09a = Entering a parking position, moving forward. • 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 35–37 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 aAbridged due to inability to observe specific DV2 behaviors and states.

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

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

101Table C.3. Incident Type Descriptions Incident Type Description Illustration Aborted lane change Approaches traffic quickly (not used) Backing in roadway Clear path for emergency vehicle 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. Driver approaches stopped or slowing traffic too quickly and has to brake hard or suddenly to avoid hitting the lead vehicle. Driver backs the vehicle while on a roadway in order to maneuver around an obstacle ahead on the roadway. 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. Emergency Vehicle 9 10 7 8 Obstacle 5 6 Stationary 3 4 1 2 (continued on next page)

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

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

104Lateral deviation of through vehicle Left turn without clearance Merge out of turn (before lead vehicle) Merge without sufficient gap Obstruction in roadway Table C.3. Incident Type Descriptions (continued) Incident Type Description Illustration 32 33 Driver has substantial lateral deviation of a through vehicle. Vehicle may or may not deviate from the lane. 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. 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. Driver merges into traffic without a sufficient gap to either the front or the back of one or more vehicles. Stationary object blocks through traffic, such as traffic that is backed up or an animal in the roadway. 34 35 36 37 38 39 40 41 42

105Proceeding through red traffic signal Roadway entrance without clearance Slow speed Slow on passing Sudden braking in roadway Table C.3. Incident Type Descriptions (continued) Incident Type Description Illustration Driver fails to respond to a red traffic signal, conflicting with a vehicle proceeding through the intersection legally. Driver turns onto a roadway without adequate clearance from through traffic. Driver is traveling at a much slower speed than the rest of the traffic, causing following traffic to pass the slow vehicle to avoid a conflict. Driver moves in front of another vehicle and then slows, causing the second (passed) vehicle to slow as well or go around the first vehicle. Driver is traveling ahead of another vehicle and brakes suddenly and improperly in the roadway for traffic or a traffic light, causing the following vehicle to come close to the braking vehicle or to also brake suddenly. 43 44 45 46 Slower Speed 47 48 49 50 Sudden Braking 51 52 53 (continued on next page)

106Through traffic does not allow lane change Through traffic does not allow merge Turn without sufficient warning Turn or exit from incorrect lane Wide turn into adjacent lane Table C.3. Incident Type Descriptions (continued) Incident Type Description Illustration Turn Signal On 54 55 Driver is trying to make a lane change (with the turn signal on) but traffic in the adjacent lane will not allow the lane change to be completed. Through traffic obstructs a driver from entering the roadway. Driver slows and turns without using a turn signal or without using a turn signal in advance. Driver turns onto a side road from the incorrect lane (e.g., driver makes a right turn from the left lane instead of the right lane). Vehicle partially enters an adjacent lane when turning. Traffic in the adjacent lane may be moving in the same or opposite direction. 56 57 58 59 60 61 62 63 64

107Conflict with object/animal/ pedalcyclist in roadway Conflict with object/animal/ pedalcyclist on side of roadway Proximity to turning vehicle Other single-vehicle event Unable to determine Table C.3. Incident Type Descriptions (continued) Incident Type Description Illustration Object/ Animal 65 Vehicle approaches an object, animal, or pedalcyclist in the roadway and either makes contact with it or performs an evasive maneuver to avoid it. Vehicle approaches an object, animal, or pedalcyclist on the side of the road and either makes contact with it or performs an evasive maneuver to avoid it. Lead vehicle is making a right or left turn or changing lanes to the right or left and the following vehicle comes close to the rear of the lead vehicle as they pass. Vehicle is involved in a single-vehicle event; for example, runs off the side of the road without a threat of hitting a fixed object. It is not possible to determine which vehicle is at fault; therefore, it is not possible to assign an incident type to the event. Object/ Animal 66 68 69• 04 = Nondisabling vehicle problem (e.g., hood flew up). • 05 = Poor road conditions (e.g., wet road, puddle, pot- hole, ice). • 06 = Traveling too fast for conditions. • 07 = Jackknife event. • 08 = Cargo shift. • 09 = Braking. • 10 = Steering. • 18 = Other cause of control loss. • 19 = Unknown cause of control loss. Travel of Vehicle (V1) • 20 = Toward or over the lane line on left side of travel lane. • 21 = Toward or over the lane line on right side of travel lane. (continued from page 99) • 22 = Toward or off the edge of the road on the left side. • 23 = Toward or off the edge of the road on the right side. • 24 = End departure. • 25 = Turning left at intersection. • 26 = Turning right at intersection. • 27 = Crossing over (passing through) intersection. • 28 = This vehicle decelerating. • 29 = Unknown travel direction. Other Motor Vehicle (V2) in Lane • 50 = Other vehicle stopped. • 51 = Traveling in same direction with lower steady speed. • 52 = Traveling in same direction while decelerating. • 53 = Traveling in same direction with higher speed. • 54 = Traveling in opposite direction. • 55 = In crossover.

108• 56 = Backing • 59 = Unknown travel direction of other motor vehicle in lane. Other Motor Vehicle (V2) Encroaching into Lane • 60 = From adjacent lane (same direction), toward or over left lane line. • 61 = From adjacent lane (same direction), toward or over right lane line. • 62 = From opposite direction, toward or over left lane line. • 63 = From opposite direction, toward or over right lane line. • 64 = From parking lane. • 65 = From crossing street, turning into same direction. • 66 = From crossing street, across path. • 67 = From crossing street, turning into opposite direction. • 68 = From crossing street, intended path not known. • 70 = From driveway, turning into same direction. • 71 = From driveway, across path. • 72 = From driveway, turning into opposite direction. • 73 = From driveway, intended path not known. • 74 = From entrance to limited-access highway. • 78 = Encroachment by other vehicle, details unknown. Pedestrian, Pedalcyclist, or Other Nonmotorist • 80 = Pedestrian in roadway. • 81 = Pedestrian approaching roadway. • 82 = Pedestrian, unknown location. • 83 = Pedalcyclist or other nonmotorist in roadway. • 84 = Pedalcyclist or other nonmotorist approaching roadway. • 85 = Pedalcyclist or other nonmotorist, unknown location. Object or Animal • 87 = Animal in roadway. • 88 = Animal approaching roadway. • 89 = Animal, unknown location. • 90 = Object in roadway. • 91 = Object approaching roadway. • 92 = Object, unknown location. Other • 93 = This vehicle not involved in first harmful event. • 98 = Other critical precrash event. • 99 = Unknown.Comment: This is LTCCS Variable 5. It is coded for both vehicles in a two-vehicle incident. However, the critical rea- son (see below) is coded for only one vehicle. For consistency with the accident type variable (28), lane edges between travel lanes and nontravel lanes (e.g., shoulders) are considered road edges; for example, events involving V1’s crossing of these edges are coded 22 or 23. Unlike the accident type variable, the analyst should code the actual precipitating event and should not project or extrapolate the event. In the list above, note the addition of 09 = loss of control caused by braking and 10 = steering. DV1 Critical Reason for the Critical Event (C-N-I) • 000a = Not applicable (baseline epoch). • 000b = Critical reason not coded to this vehicle. Driver-Related Factor: Critical Nonperformance Errors • 100 = Sleep (i.e., actually asleep). • 101 = Heart attack or other physical impairment of the ability to act. • 107 = Drowsiness, fatigue, or other reduced alertness (not asleep). • 108 = Other critical nonperformance. • 109 = Unknown critical nonperformance. Driver-Related Factor: Recognition Errors • 110 = Inattention (i.e., daydreaming). • 111 = Internal distraction. • 112 = External distraction. • 113 = Inadequate surveillance (e.g., failed to look, looked but did not see). • 118 = Other recognition error. • 119 = Unknown recognition error. Driver-Related Factor: Decision Errors • 120 = Too fast for conditions (e.g., for safe vehicle control or to be able to respond to unexpected actions of other road users). • 121 = Too slow for traffic stream. • 122 = Misjudgment of gap or other road user’s speed. • 123 = Following too closely to respond to unexpected actions (proximity for 2 or more seconds). • 124 = False assumption of other road user’s actions. • 125 = Illegal maneuver. • 125a = Apparently intentional sign/signal violation. • 125b = Illegal U-turn.

109• 125c = Other illegal maneuver. • 126 = Failure to turn on headlamps. • 127 = Inadequate evasive action (e.g., braking only instead of braking and steering; releasing accelerator only instead of braking). • 128a = Aggressive driving behavior: intimidation. (Any behavior emitted by a driver while driving that is intended to cause physical or psychological harm to another person.) • 128b = Aggressive driving behavior: wanton, neglectful, or reckless behavior. (Excessive risky driving behaviors performed without intent to harm others, such as weaving through traffic, maneuvering without signaling, running red lights, frequent lane changing, and tailgating.) • 138 = Other decision error. • 139 = Unknown decision error. • 140 = Apparent recognition or decision error (unknown which). Driver-Related Factor: Performance Errors • 141 = Panic/freezing. • 142 = Overcompensation. • 143 = Poor directional control (e.g., failing to control vehicle with skill ordinarily expected). • 148 = Other performance error. • 149 = Unknown performance error. • 199 = Type of driver error unknown. Vehicle-Related Factor • 200 = Tires/wheels failed. • 201 = Brakes failed. • 202 = Steering failed. • 203 = Cargo shifted. • 204 = Trailer attachment failed. • 205 = Suspension failed. • 206 = Lights failed. • 207 = Vehicle-related vision obstructions. • 208 = Body, doors, hood failed. • 209 = Jackknifed. • 298 = Other vehicle failure. • 299 = Unknown vehicle failure. Environment-Related Factor: Highway Related • 500 = Signs/signals missing. • 501 = Signs/signals erroneous/defective. • 502 = Signs/signals inadequate. • 503 = View obstructed by roadway design. • 504 = View obstructed by other vehicles in crash circum- stance. • 505 = Road design, roadway geometry (e.g., ramp curvature).• 506 = Road design, sight distance. • 507 = Road design, other. • 508 = Maintenance problems (e.g., potholes, deteriorated road edges). • 509 = Slick roads (low-friction road surface caused by ice, loose debris, any other cause). • 518 = Other highway-related condition. Environment-Related Factor: Weather Related • 521 = Rain, snow (Note: code loss-of-control as 509). • 522 = Fog. • 523 = Wind gust. • 528 = Other weather-related condition. Environment-Related Factor: Other • 530 = Glare. • 531 = Blowing debris. • 532 = Animal in roadway (no driver error). • 533 = Pedestrian or pedalcyclist in roadway (no driver error). • 538 = Other sudden change in ambience. • 999 = Unknown reason for critical event. Comment: LTCCS Variable 6 with revisions. “This vehicle” is always used for the vehicle being coded. Note that vehicle- related factors are rarely apparent to data reductionists. Vehicle 1 Attempted Avoidance Maneuver (C-N-I) • 00 = No driver present. • 0a = Not applicable (baseline epoch). • 01 = No avoidance maneuver. • 02 = Braking (no lockup or lockup unknown). • 03 = Braking (lockup). • 04 = Braking (lockup unknown). • 05 = Releasing brakes. • 06 = Steered to left. • 07 = Steered to right. • 08 = Braked and steered to left. • 08a = Braked and steered to left (no lockup or lockup unknown). • 08b = Braked and steered to left (lockup). • 09 = Braked and steered to right. • 09a = Braked and steered to right (no lockup or lockup unknown). • 09b = Braked and steered to right (lockup). • 10 = Accelerated. • 11 = Accelerated and steered to left. • 12 = Accelerated and steered to right. • 13 = Released gas pedal without braking.

110• 14 = Released gas pedal (without braking) and steered to left. • 15 = Released gas pedal (without braking) and steered to right. • 98 = Other actions. • 99 = Unknown if driver attempted any corrective action. Comment: LTCCS Variable 7 and GES V27, corrective action attempted. Released gas pedal elements added because this evasive maneuver by subject drivers is sometimes observed. Relevant Object (C-N-I) Analyst chooses the most relevant object; that is, one that was struck in a crash or that constituted a crash threat for near crashes and crash-relevant conflicts. • 00a = Not applicable (baseline epoch). • 00b = Not applicable (single-vehicle event but no critical object [e.g., shoulder only]). • 00c = Not applicable (two-vehicle event, pedestrian, ani- mal, etc.). • 01 = Parked motor vehicle. Fixed Objects • 02 = Building. • 03 = Impact attenuator/crash cushion. • 04 = Bridge structure (e.g., abutment). • 05 = Guardrail. • 06 = Concrete traffic barrier or other longitudinal barrier (e.g., Jersey barrier). • 07 = Post, pole, or support (e.g., sign or light). • 08 = Culvert or ditch. • 09 = Curb. • 10 = Embankment. • 11 = Fence. • 12 = Wall. • 13 = Fire hydrant. • 14 = Shrubbery or bush. • 15 = Tree (not overhang; see below). • 16 = Boulder. • 17 = Loading dock. • 18 = Loading equipment (e.g., forklift or pallets). • 19 = Cargo. Overhanging Objects The following were coded only if struck or potentially struck by the top of a truck trailer. • 20 = Tree branch. • 21 = Overhanging part of sign or post.• 22 = Bridge/overpass. • 23 = Building. • 24 = Telephone wires. Nonfixed Objects • 25 = Vehicle parts, including tire parts. • 26 = Spilled cargo. • 27 = Dead animal in roadway. • 28 = Broken tree limbs or other tree/shrub parts. • 29 = Trash/debris. • 30 = Construction barrel. • 31 = Construction cone. • 98 = Other. • 99 = Unknown object hit. Comment: Most objects are the same as those used in GES A06, first harmful event. Those in italics are not A06 codes. Driver 1 Vision Obscured (C-N-I) • 00 = No obstruction. • 01 = Rain, snow, fog, smoke, sand, dust. • 02 = Reflected glare, sunlight, headlights. • 03 = Curve or hill. • 04 = Building, billboard, or other design features (includes signs and embankment). • 05 = Trees, crops, vegetation. • 06 = Moving vehicle (including load). • 07 = Parked vehicle. • 08 = Splash or spray of passing vehicle (any other vehicle). • 09 = Inadequate defrost or defog system. • 10 = Inadequate lighting system (includes vehicle or object in dark area). • 11 = Obstruction interior to vehicle. • 12 = Mirrors. • 13 = Head restraints. • 14 = Broken or improperly cleaned windshield. • 15 = Fog. • 16 = Other vehicle or object in blind spot. • 50 = Hit-and-run vehicle. • 95 = No driver present. • 96 = Not reported. • 97 = Vision obscured, no details. • 98 = Other obstruction. • 99 = Unknown whether vision was obstructed. Comment: GES Variable D4. Element 16 added because of relevance to large trucks. Elements 50, 95, and 96 are not applicable.

111Driver Fatigue Monitor Operating Mode (C-N-I-B) • 01 = Auto-manual. • 02 = Manual. • 03 = Auto (if operating mode = auto, driver fatigue moni- tor [DFM] is automatically nonoperative). DFM Sensitivity Level (C-N-I-B) • 01 = Low. • 02 = Medium. • 03 = High. Rules to Follow When Trying to Determine If DFM Is in Standby • When speed is below 30 mph (48.28 kph) and ambient brightness is above 100, the DFM is in standby. • When the speed is above 35 mph (56.32 kph) and ambient brightness is less than 50, the DFM is active. • Ambient brightness (0 = dark; 255 = bright). Special note: Sometimes when the DFM should be func- tioning according to the rules above but often during dawn and dusk, it still does not operate correctly. If it looks light in the video but the ambient brightness values are within the correct range, a judgment call might be needed to determine whether it is working. Please ask if there are any questions. Average PERCLOS over 1 Min (C-N-I-B) Comment: Recorded parameter from DFM, averaged over a 1-min period before the initiating event. Coded when avail- able for time epoch. Format: Percent; 999 = DFM not operative. Average PERCLOS over 3 Min (C-N-I-B) Comment: Recorded parameter from DFM, averaged over a 3-min period before the initiating event. Coded when avail- able for time epoch. Format: Percent; 999 = DFM not operative.Average PERCLOS over 5 Min (C-N-I-B) Comment: Recorded parameter from DFM, averaged over a 5-min period before the initiating event. Coded when avail- able for time epoch. Format: Percent; 999 = DFM not operative. Observer Rating of Driver Drowsiness (C-N-I-B) Note: Analysts use a 100-point scale to code observer rating of drowsiness (ORD). They can choose any value (e.g., 35, 62, or 87) on the scale in Figure C.1. The five given points are to be used as guidelines. If ORD is 25 or greater, mark drowsy, sleepy, asleep, fatigued, other reduced alertness under Driver 1 behaviors. • 999 = Driver is wearing sunglasses or eyes are otherwise blocked from view. • 00 = Not drowsy. (No signs of being drowsy.) • 25 = Slightly drowsy. (Driver shows minor signs of being drowsy [e.g., single yawn, single stretch, or droopy eyes for a short period]; quickly recovers; does not have any appar- ent impact on vehicle control.) • 50 = Moderately drowsy. (Driver shows signs of being drowsy [e.g., yawns, stretches, moves around in seat, droopy eyes for a slightly longer period, or minor blinking]; takes slightly longer to recover; does not have any apparent impact on vehicle control.) • 75 = Very drowsy. (Driver shows signs of being drowsy [e.g., yawns often, has very heavy or droopy eyes, or blinks frequently]; duration lasts much longer; does not have any apparent impact on vehicle control.) • 100 = Extremely drowsy. (Driver shows extreme signs of being drowsy [e.g., yawns often, has very heavy or droopy eyes, has trouble keeping eyes open, or blinks very fre- quently]; duration lasts much longer; has apparent impact on vehicle control.) Comment: An ORD is assigned for 1 min before the event based on review of driver videos. Three-, 6-, and 20-min ORDs are not obtained, because of the labor required and difficulties in averaging reliably over these periods.0 Not Drowsy 50 Moderately Drowsy 25 Slightly Drowsy 75 Very Drowsy 100 Extremely Drowsy Figure C.1. Driver drowsiness scale.

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

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

114Table C.4. Applicable Countermeasures for Vehicle 1 Scenario/Driver Code No. Functional Countermeasure Error Source(s) DV2? Comments 0a 0b 0c 0d 1 2 3 4 5 6 7 8 9 10 Not applicable (baseline epoch) No countermeasure applicable to this driver/vehicle (no driver error and/or coded to other vehicle only) No obvious or plausible countermeasure applicable to this driver/vehicle (e.g., insufficient information because of random occurrence) Not applicable: single-vehicle event Increase driver alertness (reduce drowsiness) Improve commercial driver hours-of-service (HOS) compli- ance (i.e., reflective of alertness-related incident during HOS violation period) Prevent drift lane departures (e.g., caused by fatigue, inattention, or misjudgment of lines) Improve vehicle control/stability on curves Improve vehicle control/stability on slippery road surfaces Improve vehicle control/stability during braking Improve vehicle control/stability during evasive steering Increase driver attention to forward visual scene (e.g., eyes on road) Increase/improve driver use of mirrors or provide better information from mirrors (or from other indirect visibility systems) Improve general driver situation awareness and/or proactive/defensive driving NA NA NA Veh/Nonmotorists involved = 01, 05–07 CR = 100 or 107 Or analyst judgment considering PERCLOS, ORD, driver behavior AT = 01 or 06 Trigger Type = 1 And PEM = 14 And AT = 02, 07, 46, 47, or 50 Road surface = 2–5 And CPE = 05 CPE = 09 Or Avoidance maneu- ver = 3 CPE = 10 Or Avoidance maneu- ver = 6–9 with LOC Analyst judgment, considering poten- tial distractions coded (V39) and CR (e.g., 110–119, 140) AT = 46, 47, 70, 73, 76, 78, or others TBD and Vision Obscured = 12 or 16 Analyst judgment Never coded for V1 Not coded during Phase I; potential for Phase II. No evidence of intention (e.g., lane change). Assumes potential rollover or other LOC event; no triggers for V2. Not coded if 1 and/or 8 are coded. Yes Yes Yes Yes No No Yes Yes Yes Yes Yes No No No

11512 13 14 15 16 17 18 19 20 21 22 23 24 Table C.4. Applicable Countermeasures for Vehicle 1 (continued) Scenario/Driver Code No. Functional Countermeasure Error Source(s) DV2? Comments Reduce road/highway travel speed Reduce speed on downgrades Reduce speed on curves or turns Reduce speed at or on exits (including ramps) Limit top speed to 70 mph (except on downgrades) Increase driver recognition/appreciation of specific high- way crash threats: stopped vehicle(s) in lane ahead traveling in same direction Increase driver recognition/appreciation of specific high- way crash threats: moving/decelerating vehicle(s) in lane ahead traveling in same direction Increase driver recognition/appreciation of specific highway crash threats: vehicle in left adjacent lane on highway Increase driver recognition/appreciation of specific highway crash threats: vehicle in right adjacent lane on highway Increase driver recognition/appreciation of specific high- way crash threats: vehicle in left adjacent lane during merging maneuver Increase driver recognition/appreciation of specific high- way crash threats: vehicle in right adjacent lane during merging maneuver Increase driver recognition of crossing or oncoming traffic at intersections Improve driver gap judgment relating to crossing or oncoming traffic at intersections CR = 120 Or Driver behavior = 1, 43 CR = 120 and Profile = 2b or Driver B = 1, 43 and Profile = 2b CR = 120 and Alignment = 2a, 2b Or Driver B = 1, 43 and Alignment = 2a, 2b CR = 120 and Profile = 2b or Driver B = 1, 43 and Profile = 2b Prevented speed greater than 70 mph; analyst judgment Evidence: CR = 120; Driver A/F/B = 1 AT = 11, 20 And CR = 107–119 AT = 24, 28 And CR = 107–119 AT = 47 And CR = 107–119 AT = 46 And CR = 107–114 AT = 47, 78 And PEM = 16 And CR = 107–119 AT = 46, 76 And PEM = 16 And CR = 107–119 AT = 76, 78, 80, 82–91 And CR = 107–119 AT = 76, 78, 80, 82–91 And CR = 122 Includes all road configurations and thus is inclusive of 14–16 but does not include all speeds above speed limit; must be significant factor. Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes (continued on next page)

11625 26 27 28 29 30 32 33 34 35 36 37 38 Table C.4. Applicable Countermeasures for Vehicle 1 (continued) Scenario/Driver Code No. Functional Countermeasure Error Source(s) DV2? Comments Improve driver response execution of crossing or turning maneuver at intersections (performance failure) Improve driver recognition, gap judgment, or response execution at intersection (specific cause not determined) Improve driver compliance with intersection traffic signal (e.g., red light) controls (includes both intentional and unintentional intersection control violations) Improve driver compliance with intersection traffic sign (e.g., stop or yield sign) controls (includes both inten- tional and unintentional intersection control violations) Increase forward headway during vehicle following Improve driver night vision in forward field Provide warning to prevent rear encroachment or tailgat- ing by other vehicle (i.e., this vehicle is lead vehicle, other vehicle is following) Provide advisory to driver regarding reduced road-tire friction (i.e., associated with slippery roads) Prevent vehicle mechanical failure (e.g., brakes, steering, or tire blowout) Other, specify Prevent splash and spray from this vehicle affecting other vehicle(s) Improve driver recognition/gap judgment relating to oncoming vehicle during passing maneuver Prevent animals from crossing roadways AT = 76, 78, 80, 82–91 And CR = 141–199 AT = 76, 78, 80, 82–91 And CR = 140 or 199 Driver A/F/B = 28–30 Driver A/F/B = 31–33 AT = 24, 28 And CR = 123 Light = 2, 3 And AT = 1–14, 20, 34, 36, 38, 40 And analyst judgment AT = 21, 22, 23, 25, 26, 27, 29, 30, 31 Roadway surface condition = 2–5 And LOC And analyst judgment CR = 200–209, 298, 299 Analyst judgment AT = 25, 26, 35–41, 45–47 And analyst judgment And Roadway surface condition = 2, 3 PEM = 06 And AT = 50 or 64 And CR = 110–119, 120–122, or 128–140 Vehicle/Person 2 Type = 13 or 14 Applies to tailgating scenarios, not rapid closing scenarios. CM would provide earlier driver recogni- tion of distant object (e.g., pedestrian walking in roadway) Reciprocal relation between 17 and 18 and 32 (i.e., if one vehicle is coded 17 or 18, other vehicle is coded 32). Probably undercounted in instrumented vehicle studies. When possible, analyst will specify asso- ciated precrash/causation algorithm and add to list of CMs. Applicable to all animal-related events. Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No

11739 40 98 99 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. Table C.4. Applicable Countermeasures for Vehicle 1 (continued) Scenario/Driver Code No. Functional Countermeasure Error Source(s) DV2? Comments Navigation system/routing aid Aid to vertical clearance estimation Driver error and/or vehicle failure apparent for this vehicle but countermeasure(s) to address it unknown Unknown Driver A/F/B = 49 Object = overhanging object Vehicle has CR but no other CM specified Used when truck hits or has the potential to hit overhanging object (e.g., tree limb). Not coded if other CMs coded. Not coded if other CMs coded. No No Yes Yes• 02 = Van (minivan or standard van). • 03 = Pickup truck. • 03a = SUV (includes Jeep). • 04 = Bus (transit or motor coach). • 05 = School bus. • 06 = Single-unit straight truck (includes panel truck, U-Haul truck). • 07 = Tractor-trailer. • 08 = Motorcycle or moped. • 09 = Emergency vehicle (police, fire, EMS; in service) • 10 = Vehicle pulling trailer (other than tractor-trailer). • 11 = Other vehicle type. • 12 = Pedestrian. • 13 = Pedalcyclist. • 14 = Deer. • 15 = Other animal. • 99 = Unknown vehicle type. Comment: Highly abridged version of GES V5, body type. If Driver/Vehicle 2 is a pedestrian, cyclist, animal, or object, most other DV 1 file variables are coded not applicable. Vehicle 2 Position (in Relation to V1) (C-N-I) • 00 = Not applicable (baseline epoch). • 00a = Not applicable (single-vehicle event). • K = Top of vehicle. Comment: The vehicle in Figure C.2 represents the DV1 (the truck). The relative position of Vehicle 2 (in relation to Vehi- cle 1) is coded for the time in which the critical event occurs; 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 E, depending on their position. Baseline epochs are coded 0. (continued from page 113) Front J A B I C H D G F E Rear Figure C.2. Vehicle diagram.Vehicle 2 Pre-Event Movement (C-N-I) • 00 = No driver present. • 00a = Not applicable (single-vehicle event). • 01 = Going straight. • 02 = Decelerating in traffic lane. • 03 = Accelerating in traffic lane. • 04 = Starting in traffic lane. • 05 = Stopped in traffic lane. • 06 = Passing or overtaking another vehicle. • 07 = Disabled or parked in travel lane. • 08a = Leaving a parking position, moving forward. • 08b = Leaving a parking position, backing. • 09a = Entering a parking position, moving forward. • 09b = Entering a parking position, backing. • 10 = Turning right. • 11 = Turning left. • 12 = Making a U-turn. • 13 = Backing up (other than parking). • 14 = Negotiating a curve. • 15 = Changing lanes. • 16 = Merging. • 17 = Successful avoidance maneuver to a previous critical event. • 98 = Other. • 99 = Unknown.

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

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

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

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

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