# Presentation: 144679

## Three Stories from the LTCCS:Using the LTCCS for Safety Research

**Daniel Blower**
**June 4, 2008**

## Purpose of Presentation

**Illustrate the strengths and limitations of the LTCCS using experience from three research projects:**
**Truck mirrors and blind zones.**
**Evaluating effectiveness of advanced stability technologies.**
**Effect of truck mechanical condition on truck crashes.**

## Crash Data Overview

**Trucks Involved in Fatal Accidents (TIFA)**
**Fatal crashes only; census file; survey to supplement FARS; since 1980.**
**General Estimates System (GES)**
**All police-reported crashes; sample file; nationally representative; since 1987.**
**Large Truck Crash Causation Study (LTCCS)**
**Fatal, A-, B-injury crashes; sample file; nationally-representative; 2001-2003**

## Story One:Blind Zone Crashes and Truck Mirrors

## National crash data show that mirror-relevant crashes overinvolved on the right.
No detail on truck mirror configuration in any available crash data.
Large Truck Crash Causation Study data offers more detailed information.
Presence of side & fender mirrors.
Available materials such as scene diagram, photos, extensive narrative, interviews with all parties to code additional data.

**No detail on truck mirror configuration in any available crash data.**
**Large Truck Crash Causation Study data offers more detailed information.**
**Presence of side & fender mirrors.**
**Available materials such as scene diagram, photos, extensive narrative, interviews with all parties to code additional data.**

## Crash Types in Which Conflict Only Visible Using Mirrors

- Mirror-relevant ~20% of all
- LCM right 4.5 times LCM left
- Right turn 4.4 times left turn
- Backing ~ 7% of all

**Data: TIFA, GES**

## Mirror and Direct Fields of View for One Truck & Driver

**Mirror and Direct Fields of View for One Truck & Driver**

- Blocked by left planar mirror

- Blocked by A Pillar

- Source of drawing: Matthew Reed, UMTRI

**Note car fits neatly in area visible only using fender-mirror**

**Area visible using fender mirror**

**Area visible using planar mirror**

## Hypothesis

**Fender-mounted mirrors reduce the over-representation of right-side blind zone crashes.**

## Method

**Reproduce classification algorithm in LTCCS data.**
**Review scene diagrams/narrative to verify blind zones. **
**Code position of conflict vehicles.**
**►**** ****Are the vehicles in the blind zones?**
**Compare crash configuration with mirror configuration. **
**►**** ****Do right fender-mounted mirrors help?**

## Mirror-relevant Crash InvolvementsLTCCS

**Mirror-relevant are 7.2% of all.**
**LCM Right 1.9 times LCM Left**
**Right turn 0.7 times left turn**
**Backing ~0.3%**

## Mirror-relevant Crash InvolvementsLTCCS

**Mirror-relevant are 7.2% of all.**
**LCM Right 1.9 times LCM Left**
**Right turn 0.7 times left turn**
**Backing ~0.3%**

## Comparison of Mirror-Relevant Crashes in LTCCS, TIFA/GES

**Less over-representation on the right.**
**Relationship in turns not observed.**
**Overall proportion of involvements similar.**

## LCM Crashes, Position of Conflict Vehicle and Blind Zones

- Left planar mirror

- A Pillar

- Source of drawing: Matthew Reed, UMTRI

**24.8**

**38.8**

**27.8**

**8.6**

**LCM Crashes, Position of Conflict Vehicle and Blind Zones**

## Association of Fender/hood Mounted Mirrors with LCM Crash

**Percentage with Left Fender Mirrors**

**Percentage with Right Fender Mirrors**

**Trucks in LCM Right crashes somewhat **_**more**_** likely to have right fender mirrors.**
**Trucks in LCM Left crashes somewhat **_**less**_** likely to have left fender mounted mirrors.**
**Neither difference is statistically significant.**
**29 unweighted LCM right cases.**
**23 unweighted LCM left cases.**

**Notes:**
No fender mounted mirrors in 55% of crash population.

Right mirror in 33.4%

## Cautions

**Small sample sizes limit conclusions: the size of the effects are not statistically significant.**
**LTCCS not well-suited for analysis of infrequent events.**
**Use of researcher’s summary, diagrams, photographs is labor intensive but worth the effort.**

## Story Two:Evaluating Technology to Reduce Rolloverand Loss of Control Crashes

## Current Project to Estimate Effectiveness of Advanced Stability Technologies

**Roll stability control & electronic stability control technologies available for trucks.**
**Goal is to reduce rollover & loss of control crashes.**
**Current project to estimate effectiveness in real-world crashes.**

## Method

**Identify scope of crashes where the technology is relevant.**
**Identify vehicle & environmental factors that contribute to the crashes.**
**Engineering evaluation of real-world crashes to estimate effect.**
**Hardware-in-the-loop simulation of technologies in real-world crashes.**

## Relevant Crashes in TIFA, GES, & LTCCS 

**(K)         (K, A, B)    (K, A, B)**

**(K)         (K, A, B)    (K, A, B)**

## Use of LTCCS Cases

**Specific limitations:**
**Relatively few cases: 963 crashes, 1123 vehicles.**
**Questions about national representativeness. (E.g., about twice as many rollovers as expected)**
**Therefore, in light of the limitations:**
**Use TIFA/GES to determine national distribution of yaw & roll instability crash scenarios**
**Apply algorithm to classify yaw and roll cases developed in TIFA/GES to LTCCS to establish crash types**
**Exploit superior detail of LTCCS to produce exemplars of the crash types for engineering review and simulation**

## Review of LTCCS Yaw & Roll Instability Crashes

**Review of:**
**83 yaw instability cases **
**81 roll instability cases**
**Assess for**
**Accuracy of coding**
**Suitability for Hardware in the Loop simulation**
**Crash details (radius of curvature, curve entry speed)**
**Relevance of roll & yaw control technologies (likely, probably, unlikely, unknown)**

## Road curved 

- Road curved
- Dry surface
- Cargo: loaded
- 3-axle tractor pulling bottom dump.
- 31,000 lbs cargo (dirt)
- 61,800 gross weight
- Est. 40 mph

- LTCCS Rollover Case for Simulation

## Researcher’s Narrative from LTCCS

**Researcher’s Narrative from LTCCS**

- Engineering assessment: Roll control likely relevant; Yaw control unlikely relevant

## Lessons

**Very rich crash investigations, scene & vehicle documentation support engineering analysis.**
**Both uniform and of high quality.**
**Reasons to question some national estimates from LTCCS.**
**No current alternative for rich detail available from LTCCS.**

## Story Three:Vehicle Mechanical Condition and Crash Risk

## State-level Research Showed Vehicle Mechanical Condition Related to Crash Role

**FACT data from Michigan, 1996-2001**
**CVSA Level 1 inspection & detailed crash events**
**Rear-end crashes:**
**Higher rates of **_**brake**_** violations when the truck is the **_**striking**_** vehicle.**
**Higher rates of **_**light**_** violations when truck is the **_**struck**_** vehicle**
**FACT program a forerunner of LTCCS**

## Brake Violations Increase Risk of Striking in Rear-end CrashesFACT data 

| Brakeinspection results | Rear-end type |  | Total |
| --- | --- | --- | --- |
|  | Truck striking | Truck struck |  |
| 0 violations | 15 | 26 | 41 |
| 1 or more violation | 17 | 11 | 28 |
| Total | 32 | 37 | 69 |
|  | proportion with violations |  |  |
| 0 violations | 46.9 | 70.3 | 59.4 |
| 1 or more violation | 53.1 | 29.7 | 40.6 |
| Total | 100.0 | 100.0 | 100.0 |
| chi=3.89, p=0.05 |  |  |  |

## Lights Violations Increase Risk of Being Struck in Rear-end CrashesFACT data

| Inspection results | Rear-end type |  | Total |
| --- | --- | --- | --- |
|  | Truck striking | Truck struck |  |
| 0 violations | 28 | 23 | 51 |
| 1 or more violations | 4 | 14 | 18 |
| Total | 32 | 37 | 69 |
|  | Proportion of lighting violations |  |  |
| 0 violations | 87.5 | 62.2 | 73.9 |
| 1 or more violations | 12.5 | 37.8 | 26.1 |
| Total | 100.0 | 100.0 | 100.0 |
| chi=5.71, p=0.02 |  |  |  |

## LTCCS Vehicle Inspection Data Much More Comprehensive

| Inspection category | LTCCS |  | FARS/TIFA  |
| --- | --- | --- | --- |
|  | OOS | Violation |  |
| Brakes | 21.7 | 42.1 | 1.9 |
| Log | 8.0 | 23.0 | n/a |
| Lights | 4.1 | 22.4 | 0.3 |
| Load securement | 3.4 | 4.6 | n/a |
| Tires | 3.3 | 14.3 | 0.9 |
| Suspension | 2.3 | 3.5 | 0.1 |
| HOS | 1.4 | 4.3 | n/a |
| Steering | 1.2 | 1.8 | 0.1 |
| Frame | 1.0 | 3.1 | 0.0 |
| Wheels | 0.8 | 3.5 | incl. w/tires |
| Any OOS or violation | 35.1 | 70.5 | 6.8 |

## Brake Violations More Likely When Truck is Striking Vehicle in Rear-end Crashes in LTCCS

**In rear-end crashes, trucks that are the striking vehicle have higher rates of brake violations and out-of-service than as the struck vehicle.**
**Neither difference is statistically significant.**
**Same pattern as Michigan FACT data**

**Notes:**
No fender mounted mirrors in 55% of crash population.

Right mirror in 33.4%

## Mixed Results for Light System Violations in Rear-end Crashes, LTCCS

**In rear-end crashes, trucks that are the struck vehicle have higher rates of light system OOS. **
**Rates the same for all lights violations.**
**Neither difference is statistically significant.**
**Different pattern from the Michigan FACT data**

**Notes:**
No fender mounted mirrors in 55% of crash population.

Right mirror in 33.4%

## Lessons to Apply

**LTCCS invaluable as source of detailed crash data.**
**Engineering reviews of crash narratives, etc.**
**Availability of critical information such as mirror configuration and mechanical condition.**
**Restricted sample sizes pose problems **
**Care must be used in choosing truck safety **_**issues**_** and **_**methods**_** to address.**
**Representativeness can be an issue.**

## Thank you.Questions?