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The Large Truck Crash Causation Study (LTCCS) is based on a three-year data collection project conducted by the Federal Motor Carrier Safety Administration (FMCSA) and the National Highway Traffic Safety Administration (NHTSA) of the United States Department of Transportation (DOT). LTCCS is the first-ever national study to attempt to determine the critical events and associated factors that contribute to serious large truck crashes so agencies within DOT and others can implement effective countermeasures to reduce the occurrence and severity of these crashes.

For further information about the study please see the Study Methodology and database User’s Manual.

An introduction to the study results are provided in the following summary tables. The tables have been organized into two categories representing "Un-weighted" and "Weighted" results, with the specifics detailed below.

Notes:

1. Throughout the study materials and the summary tables, "truck" refers to a vehicle designed, used, or maintained primarily for carrying property, with a gross vehicle weight rating or gross combination weight rating of more than 10,000 lbs.
2. In the summary tables:
   • Percentages are rounded to the nearest whole number with values less than .5 percent rounded to zero.
   • Totals and sub-totals are summed using unrounded estimates; therefore they may not appear to equal the sum of the relevant variables.

Un-weighted Data

The tables in the "Un-weighted Data" section provide the actual study results for the table’s subject area.

Table 1: Crashes by Vehicle Count

This table shows the number of crashes in the study sample cases by the total number of vehicles involved in each crash. ^†

Vehicle Count	Crash Count	Percentage
One	241	25%
Two	488	51%
Three or More	234	24%
Total	963	100%

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Table 2: Crashes by Severity Level

This table shows the number of crashes in the study sample cases by the highest injury severity level of any individual involved in the crash. ^†

Crash Severity	Crash Count	Percentage
K − Fatal	221	23%
A − Incapacitating injury	277	29%
B − Non-incapacitating injury	465	48%
Total	963	100%

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Table 3: Crashes by Roadway Type

This table shows the number of crashes in the study sample cases by type of roadway on which the crash occurred. For crashes involving multiple roadway types, e.g. intersections, the roadway type is determined from the perspective of the vehicle associated with the critical reason for the crash. The critical reason is the reason for the critical event. ^†

Roadway Type	Crash Count	Percentage
Rural	350	36%
Principal arterial − Interstate	109	11%
Principal arterial − other	78	8%
Minor arterial	62	6%
Major collector	26	3%
Minor collector	31	3%
Local	37	4%
Unknown	7	1%
Urban	609	63%
Principal arterial − Interstate	344	36%
Principal arterial − Freeways and Expressways	63	7%
Principal arterial − other	78	8%
Minor arterial	44	5%
Collector	22	2%
Local	58	6%
Unknown	4	0%
Total	963	100%

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Table 4: Crashes by Crash Type

This table shows the number of crashes in the study sample cases by crash type, e.g. rear-end, head-on, etc. Crash type is determined from the perspective of the truck. The crash type of crashes involving two or more trucks is determined from the perspective of the truck assigned the critical reason. ^†

Crash Type	Crash Count	Percentage
Rear-end	231	24%
Roadside Departure	158	16%
Sideswipe, Same Direction	111	12%
Turn Across or Into Path	94	10%
Intersecting Vehicles, Straight	64	7%
Rollover	61	6%
Hit Object in Road	43	5%
Sideswipe, Opposite Direction	42	4%
Head-on	34	4%
No Impact − includes incidents such as fire or immersion.	12	1%
Backing	7	1%
Other − principally trucks not involved in first harmful event, or cargo spills	106	11%
Total	963	100%

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Table 5: All Trucks by Vehicle Configuration

This table shows the number of trucks in the study sample cases grouped by truck configuration. ^†

Vehicle Configuration	Number	Percentage
Single Unit Trucks
Two Axles	124	11%
Three Axles or more	157	14%
Axles Unknown	2	0%
Combination Trucks
Truck Tractor − Bobtail	29	3%
Truck pulling Trailer(s)	40	4%
Tractor pulling Trailer	697	62%
Tractor pulling Two Trailers	54	5%
Other/Unknown/Missing
Other/Unknown/Missing	20	2%
Total	1,123	100%

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Table 6: All Trucks by Cargo Body Type

This table shows the number of trucks in the study sample cases by type of truck cargo body. ^†

Cargo Body Type	Crash Count	Percentage
Van	515	46%
Closed van	383	34%
Refrigerated van	105	9%
Open top van	27	2%
Dump	184	16%
Dump (rear)	164	15%
Bottom dump/hopper bottom	20	2%
Flatbed	163	15%
Flatbed	122	11%
Flatbed with sides	21	2%
Low boy	11	1%
Flatbed with equipment	9	1%
Tank	71	6%
Tank-liquid	56	5%
Tank-dry bulk	14	1%
Tank-compressed gas	1	0%
Other	190	17%
Garbage/refuse	44	4%
Cement mixer	24	2%
Pole/logging	12	1%
Auto carrier	6	1%
Livestock carrier	5	0%
Other − includes tow trucks, etc.	49	4%
Bobtail Unit − no cargo body	28	3%
Not Inspected/Unknown	22	2%
Total	1,123	100%

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Table 7: All Trucks by Pre-Crash Movement

This table shows the number of trucks in the study sample cases by pre-crash movement of each truck. ^†

PreCrash Movement	Number	Percentage
Traveling in Lane	803	72%
Going Straight at steady speed	609	54%
Stopped in traffic lane	109	10%
Decelerating in traffic lane	59	5%
Accelerating in traffic lane	19	2%
Starting in traffic lane	7	1%
Negotiating a Curve	168	15%
Turning	35	3%
Turning left	19	2%
Turning right	15	1%
Making a U-turn	1	0%
Other	117	10%
Successful avoidance maneuver to a previous critical event	40	4%
Changing lanes	33	3%
Passing or overtaking another vehicle	12	1%
Merging	7	1%
Backing up (other than for parking position)	6	1%
Disabled or parked in travel lane	1	0%
No driver present1	11	1%
Other	6	1%
Unknown	1	0%
Total	1,123	100%

Notes: ¹ Examples of "No driver present" include:

1. A driver outside his disabled truck which was then struck from behind,
2. A driver outside his truck which had previously suffered a rollover and was then struck in the undercarriage by a passenger vehicle,
3. A driverless truck being towed counted as one of the vehicles in the crash.

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Table 8: All Trucks by Critical Pre-Crash Event

This table shows the number of trucks in the study sample cases by critical pre-crash event. The critical pre-crash event is the event which made the crash unavoidable. ^†

Critical Pre-Crash Event	Number	Percentage
Vehicle Loss-of-Control Due to:	145	13%
Blow out/flat tire	7	1%
Disabling vehicle failure (e.g. wheel fell off)	7	1%
Non-disabling vehicle problem (e.g. hood flew up)	5	0%
Poor road conditions (Puddle, pot hole, ice, etc.)	5	0%
Traveling too fast for conditions	86	8%
Jackknife Event	12	1%
Cargo Shift	13	1%
Other cause of control loss	10	1%
Vehicle Traveling:	239	21%
Over the lane line on left side of travel lane	43	4%
Over the lane line on right side of travel lane	30	3%
Off the edge of the road on the left side	28	3%
Off the edge of the road on the right side	60	5%
End departure	1	0%
Turning left at intersection	28	3%
Turning right at intersection	19	2%
Crossing over (passing through) intersection	26	2%
This vehicle decelerating	4	0%
Other Motor Vehicle in Lane:	283	25%
Other vehicle stopped	68	6%
Traveling in same direction with low steady speed	29	3%
Traveling in same direction while decelerating	49	4%
Traveling in same direction with higher speed	123	11%
Traveling in opposite direction	13	1%
In crossover	1	0%
Other Motor Vehicle Encroaching into Lane From:	233	21%
Adjacent lane (same direction) − over left lane line	43	4%
Adjacent lane (same direction) − over right lane line	53	5%
Opposite direction − over left lane line	70	6%
Opposite direction − over right lane line	1	0%
Crossing street − turning into same direction	1	0%
Crossing street − across path	46	4%
Crossing street − turning into opposite direction	15	1%
Driveway − turning into same direction	1	0%
Driveway − across path	1	0%
Driveway − turning into opposite direction	2	0%
Pedestrian, Pedalcyclist, or other NonMotorist:	31	3%
Pedestrian in roadway	24	2%
Pedestrian approaching roadway	1	0%
Pedalcyclist or other nonmotorist in roadway	6	1%
Object or Animal:	5	0%
Animal in roadway	1	0%
Object in roadway	4	0%
Other:	187	17%
Not involved first harmful event1	163	15%
Other	24	2%
Total	1,123	100%

Notes: ¹ Cases categorized as "Not involved first harmful event" are those in which the truck was not involved in the first harmful event in the crash sequence. The term First Harmful Event refers to the first event of the crash to cause damage or injury.

Weighted Data

During the three-year study period of the project, FMCSA estimated that there were approximately 141,000 large trucks involved in fatal, incapacitating, and non-incapacitating injury crashes. Each of the 963 LTCCS study cases was assigned a sampling weight (based on the probability of selection into the sample for the site associated with the case) that allows for national estimates of total truck crashes, broken down by various characteristics for these 141,000 trucks.

The summary tables in the following section illustrate the weighted results for the subject areas presented. The estimates presented may differ from true values because they are based on a probability sample of crashes and not a census of all crashes. The size of these differences may vary depending on which sample of the crashes is the focus of each particular table and analysis.

Notes:

1. Percentages are rounded to the nearest whole number with values less than .5 percent rounded to zero.
2. Totals and sub-totals are summed using unrounded estimates; therefore they may not appear to equal the sum of the relevant variables.
3. Weighted data numbers are rounded to the nearest 1000.

Table 9: All Trucks by Crash Type

This table gives the weighted number of vehicles in study sample cases by crash configuration. In determining crash configuration crashes are first categorized by Vehicle Count – one vehicle, two vehicles, or three or more vehicles.

The term Passenger Vehicle refers to automobiles, pickup trucks, vans, and sport utility vehicles. The term Other includes buses, motorcycles, and construction equipment other than trucks. For crashes involving three or more vehicles, the crash configurations are determined by the first two vehicles to collide.

Crash Configuration Other includes all trucks not involved in the initial collision. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

Table 10: All Trucks by Driver Age

This table shows the estimated number of trucks involved in study sample cases nation-wide by age of driver. ^††

Table 11: All Trucks by Critical Pre-Crash Event

This table shows the estimated number of trucks involved in crashes nation-wide. Counts of trucks are organized by the critical pre-crash event. The critical pre-crash event is the event which made the crash unavoidable. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

¹ Cases categorized as "Not involved first harmful event" are those in which the truck was not involved in the first harmful event in the crash sequence. The term First Harmful Event refers to the first event of the crash to cause damage or injury.

Table 12: All Trucks by Critical Pre-Crash Event - Trucks Assigned Critical Reason

This table shows the estimated number of trucks involved in crashes nation-wide, in which the truck was assigned the critical reason for the crash. Counts of trucks are organized by the critical pre-crash event. The critical pre-crash event is the event which made the crash unavoidable. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

¹ Cases categorized as "Not involved first harmful event" are those in which the truck was not involved in the first harmful event in the crash sequence. The term First Harmful Event refers to the first damage or injury-producing event in the crash.

Table 13: All Trucks by Critical Reason

This table shows the estimated number of trucks involved in crashes nation-wide, in which the truck was assigned the critical reason for the crash. Counts of trucks are organized by critical reason. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

Table 14: All Trucks by Associated Factors

This table shows the estimated number of trucks involved in crashes nation-wide by specific factors associated with the particular crash in which that truck was involved. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

Table 15: Trucks and Passenger Vehicles by Critical Pre-Crash Event - Vehicles Assigned Critical Reason

This table shows the estimated number of trucks and passenger vehicles involved in crashes nation-wide in which the truck or passenger vehicle was assigned the critical reason. Counts of vehicles are organized by critical pre-crash event. The critical pre-crash event is the event which made the crash unavoidable. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

¹ Cases categorized as "Not involved first harmful event" are those in which the truck was not involved in the first harmful event in the crash sequence. The term First Harmful Event refers to the first event of the crash to cause damage or injury.

Table 16: Trucks and Passenger Vehicles by Critical Reason

This table shows the estimated number of trucks and passenger vehicles involved in crashes nation-wide in which the truck or passenger vehicle was assigned the critical reason. Counts of vehicles are organized by critical reason. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

Table 17: Trucks and Passenger Vehicles by Associated Factors

This table shows the estimated number of trucks and passenger vehicles involved in crashes nation-wide by specific factors associated with the particular crash. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

Table 18: Trucks in One-Vehicle Crashes by Critical Pre-Crash Event − Trucks Assigned Critical Reason

This table shows the estimated number of trucks nation-wide involved in one-vehicle crashes in which the truck was assigned the critical reason. Counts of trucks are organized by critical pre-crash event. The critical pre-crash event is the event which made the crash unavoidable. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

Table 19: Trucks in One-Vehicle Crashes by Critical Reason

This table shows the estimated number of trucks nation-wide involved in one-vehicle crashes by critical reason ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.

Table 20: Trucks in One-Vehicle Crashes by Associated Factors

This table shows the estimated number of trucks nation-wide involved in one-vehicle crashes by specific associated factor. ^††

Notes: *** Weighted numbers lower than 500 are rounded to zero.