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Home / FHWA Review of ET-Plus / Safety Analysis of Extruding W-Beam Guardrail Terminal Crashes / Appendix C

FHWA Review of ET-Plus

Safety Analysis of Extruding W-Beam Guardrail Terminal Crashes

Appendix C – Narrative Summary of 231 Crash Cases from Harman Data Source

This summary presents FHWA's observations of the crash cases contained in the spreadsheet and supporting documentation provided by the source. FHWA received a spreadsheet summarizing crash cases from 231 locations, by State, in which the source indicated a 4-inch ET-Plus guardrail terminal failed to operate as intended. These cases included photographs of damaged terminals, photographs of damaged vehicles involved in crashes, and additional documentation such as crash reports, new articles, and legal documents. FHWA reviewed each crash case using the documentation provided by the source to independently assess whether an ET-Plus 4-inch device was involved.

Of the 231 crash cases, FHWA's assessment is that 156 involved an ET-Plus 4-inch device. In addition, FHWA identified 29 initial crash cases of significant interest for further analysis that involved severe injuries, vehicle compartment intrusion, vehicle occupant compartment penetration, spearing, rollover, snagging of rail, or otherwise appeared to be unusual or extreme.

The tables in this Appendix provide frequency totals comparing the spreadsheet of the 231 crash cases and FHWA's analysis of those cases; a review of the 156 identified and confirmed ET-Plus 4-inch crash cases; and a review of the 29 crash cases for further analysis. The tables summarize whether an ET-Plus 4-inch device was involved in the crash; whether the result of the crash involved a fatality, injury or was unknown; and what supporting documentation was provided for each crash case to include media information, crash reports, legal documentation, photographs of the damaged device, photographs of the damaged vehicles, and photographs of new or replacement devices following a crash.

Table 1 summarizes the distribution of crash cases by State. Of the 231 crash cases, 70 percent (161) are from three States: Tennessee, Texas, and Virginia.

TABLE 1 – Number of Crash Cases by State

STATE # OF CASES % OF TOTAL   STATE # OF CASES % OF TOTAL
Alabama 4 1.7% New York 1 0.4%
Arkansas 3 1.3% North Carolina 5 2.2%
California 5 2.2% Ohio 3 1.3%
Colorado 1 0.4% Oklahoma 4 1.7%
Delaware 1 0.4% Oregon 1 0.4%
Florida 2 0.9% Pennsylvania 5 2.2%
Georgia 3 1.3% Rhode Island 1 0.4%
Illinois 5 2.2% South Carolina 3 1.3%
Kentucky 1 0.4% Tennessee 75 32.5%
Maryland 7 3.0% Texas 47 20.3%
Massachusetts 2 0.9% Vermont 1 0.4%
Minnesota 1 0.4% Virginia 39 16.9%
Missouri 5 2.2% West Virginia 2 0.9%
New Hampshire 3 1.3%  
New Jersey 1 0.4% Total 231 100.0%

Table 2 summarizes the results of FHWA's independent review of the crash cases contained in the spreadsheet. FHWA reviewed the photographs for each crash case to determine whether the device had a 4-inch channel width and the head was visible. Photographs that clearly displayed a 4-inch channel width and visible head were confirmed by FHWA to be an ET-Plus 4-inch device. Conversely, photographs that clearly confirmed that the device was not an ET-Plus 4-inch (i.e., ET-Plus 5-inch or SKT) were classified as not being an ET-Plus 4-inch device. Photographs that did not clearly display the channel width or head were classified as unknown since FHWA was unable to make a determination regarding whether the device was an ET-Plus 4-inch. In addition, any crash cases that did not include photographs were also classified as unknown.

TABLE 2 – FHWA Review and Identification of ET-Plus 4-Inch Devices

FHWA OBSERVATIONS FREQUENCY % OF TOTAL
Confirmed ET-Plus 4-inch device 156* 67.5%
Non-ET-Plus 4-inch device (i.e., ET-Plus 5-inch or SKT) 6 2.6%
Unknown device 69 29.9%
Total 231 100.0%

* Note: More information about the 156 crash cases confirmed to be the ET-Plus 4-inch devices is provided in Tables 7 and 8.

Tables 3 and 4 summarize the severity of the 231 crash cases. In the source documents, the crash cases were categorized in the spreadsheet as a fatality/injury (fatalities and injuries were grouped together), no fatality/injury, or unknown. FHWA was able to further classify the cases as fatality or injury or unknown based on the documentation provided. In cases where there was no supporting documentation regarding the severity of the crash, FHWA identified those crashes as unknown. Table 3 shows the source's identification of the crash cases in the spreadsheet compared to FHWA's analysis identifying crash severity, and Table 4 shows a comparison of the crash cases.

TABLE 3 – Source Identification of Crash Severity

CRASH SEVERITY Source
OBSERVATIONS
(Spreadsheet)
% OF TOTAL FHWA
OBSERVATIONS
% OF TOTAL
Fatality 52 22.5% 19 8.2%
Injury 20 8.7%
No Fatality/Injury 1 0.4% 0 0.0%
Unknown 178 77.1% 192 83.1%
Total 231 100.0% 231 100.0%

TABLE 4 – Comparison of Crash Severity

SOURCE (Spreadsheet)
OBSERVATION
FHWA
OBSERVATION
FREQUENCY % OF TOTAL
Fatality/Injury Fatality 18 7.8%
Injury 20 8.7%
Fatality/Injury Unknown 14 6.1%
No Fatality/Injury Unknown 1 0.4%
Unknown Fatality 1 0.4%
Unknown Unknown 177 76.6%
Total   231 100.0%

Table 5 provides a summary of the types of documentation provided. FHWA reviewed all of the crash cases to identify the documentation that was provided for each case.

TABLE 5 – FHWA Review of Supporting Documentation

FHWA
Observation
Media
Information
Crash
Report
Legal
Documents
Photo of
Damaged
Device
Photo of
Vehicle
Photo of
New or
Replacement
Installation
Included in case files 23
(10.0%)
10
(4.3%)
6
(2.6%)
211
(91.3%)
35
(15.2%)
2
(0.9%)
Not included in case files 208
(90.0%)
221
(95.7%)
225
(97.4%)
20
(8.7%)
196
(84.8%)
229
(99.1%)
Total 231 231 231 231 231 231

Confirmed ET-Plus 4-Inch Crash Cases

FHWA confirmed a total of 156 crash cases to involve an ET-Plus 4-inch device summarized below using the same criteria as in Tables 1, 3, 4 and 5.

TABLE 6 – Number of Crashes by State of Confirmed ET-Plus 4-Inch Crash Cases from Source Document

STATE # OF CASES % OF TOTAL   STATE # OF CASES % OF TOTAL
Alabama 3 1.9% New York 1 0.6%
Arkansas 2 1.3% North Carolina 2 1.3%
California 1 0.6% Ohio 2 1.3%
Colorado 0 0.0% Oklahoma 3 1.9%
Delaware 1 0.6% Oregon 0 0.0%
Florida 1 0.6% Pennsylvania 4 2.6%
Georgia 3 1.9% Rhode Island 1 0.6%
Illinois 3 1.9% South Carolina 2 1.3%
Kentucky 0 0.0% Tennessee 62 39.7%
Maryland 6 3.9% Texas 24 15.6%
Massachusetts 1 0.6% Vermont 0 0.0%
Minnesota 0 0.0% Virginia 28 18.2%
Missouri 3 1.9% West Virginia 1 0.6%
New Hampshire 2 1.3%  
New Jersey 0 0.0% Total 156 100.0%

TABLE 7 – FHWA Identification of Crash Severity of Confirmed ET-Plus 4-Inch Crash Cases

CRASH SEVERITY

SOURCE
OBSERVATIONS
(Spreadsheet)

% OF TOTAL

FHWA
OBSERVATIONS

% OF TOTAL

Fatality

13

8.3%

5

3.2%

Injury

4

2.6%

Unknown

143

91.7%

147

94.2%

Total

156

100.0%

156

100.0%

TABLE 8 – Comparison of Crash Severity of Confirmed ET-Plus 4-Inch Crash Cases

SPREADSHEET
OBSERVATION

FHWA
OBSERVATION

FREQUENCY

% OF TOTAL

Fatality/Injury

Fatality

5

3.2%

Injury

4

2.6%

Fatality/Injury

Unknown

4

2.6%

Unknown

Unknown

143

91.7%

Total

 

156

100.0%

TABLE 9 – Supporting Documentation for Confirmed ET-Plus 4-Inch Crash Cases

FHWA
Observation
Media
Information
Crash
Report
Legal
Documents
Photo of
Damaged
Device
Photo of
Vehicle
Photo of
New or
Replacement
Installation
# Included in case files 4
(2.6%)
2
(1.3%)
1
(0.6%)
153
(98.1%)
9
(5.8%)
2
(1.3%)
# Not included in case files 152
(97.4%)
154
(98.7%)
155
(99.4%)
3
(1.9%)
147
(94.2%)
154
(98.7%)
Total 156 156 156 156 156 156

29 Crash Cases Analyzed Further

Tables 10 through 14 present information regarding the 29 crash cases from the source, which the Task Force analyzed to attempt to assess the performance of the 4-inch ET-Plus. They represent cases of interest involving fatal or severe injury, vehicle occupant compartment intrusion, vehicle occupant compartment penetration, rollover, snagging of rail, or otherwise appeared to be unusual or extreme. These cases are summarized below using the same criteria that was used in Tables 1, 3, 4 and 5.

TABLE 10 – Number of Cases by States for the 29 Initial Crash Cases of Interest

STATE # OF CASES % OF TOTAL
California 2 6.9%
Florida 1 3.4%
Illinois 2 6.9%
Massachusetts 1 3.4%
Minnesota 1 3.4%
Missouri 1 3.4%
New Hampshire 1 3.4%
North Carolina 4 13.8%
Ohio 1 3.4%
Oklahoma 1 3.4%
Oregon 1 3.4%
Pennsylvania 4 13.8%
South Carolina 1 3.4%
Tennessee 4 13.8%
Texas 2 6.9%
Virginia 2 6.9%
Total 29 100.0%

TABLE 11 – FHWA Review and Identification of the ET-Plus 4-Inch for 29 Cases

FHWA OBSERVATIONS FREQUENCY % OF TOTAL
Confirmed ET-Plus 4-inch device 13 44.8%
ET-Plus 4-inch or 5-inch device 1 3.4%
Unknown device 15 51.7%
Total 29 100.0%

TABLE 12 – Independent Observations of Crash Severity for the 29 Crash Cases of Interest

OBSERVATIONS SOURCE
DOCUMENT
(Spreadsheet)
% OF TOTAL FHWA % OF TOTAL
Fatality 22 82.8% 7 24.1%
Injury 14 48.3%
No Fatality/Injury 1 3.4% 0 0.0%
Unknown 4 13.8% 8 27.6%
Total 29 100.0% 29 100.0%

Table 13 – Comparison of Crash Severity for the 29 Crash Cases of Interest

SOURCE
DOCUMENT
(Spreadsheet)
OBSERVATON
FHWA
OBSERVATION
FREQUENCY % OF TOTAL
Fatality/Injury Fatality 7 24.1%
Injury 14 48.3%
Fatality/Injury Unknown 3 10.3%
No Fatality/Injury Unknown 1 3.4%
Unknown Unknown 4 13.8%
Total   29 100.0%

Table 14 - FHWA Observations of Supporting Documentation for the 29 Crash Cases of Interest

FHWA
Observation
Media
Information
Crash
Report
Legal
Documents
Photo of
Damaged
Device
Photo of
Vehicle
Photo of
New or
Replacement
Installation
# Included in case files 11
(37.9%)
5
(17.2%)
3
(10.3%)
23
(79.3%)
16
(55.2%)
0
(0.0%)
# Not included in case files 18
(62.1%)
24
(82.8%)
26
(89.7%)
6
(20.7%)
13
(44.8%)
29
(100.0%)
Total 29 29 29 29 29 29

Summary

The majority of the 231 cases (177 cases or 77%) provided in the source document include only photos of a damaged device, the date the photos were taken, and the route location of where the damage occurred.

Due to the lack of complete information, FHWA could only confirm that the ET-Plus 4-inch device was involved in 156 cases (or 68% of the cases) with the greatest number of cases in Tennessee (62 or 40%). Based on FHWA's observations, 5 fatal crashes and 4 injury crashes (out of the 156 cases) were confirmed involving an ET-Plus 4-inch device.

Of the 231 cases, FHWA analyzed the 29 cases as presented in Tables 10 through 14. These crashes were identified for further analysis because they involved severe injury, vehicle compartment intrusion, spearing of the vehicle, vehicle occupant compartment penetration, rollover, snagging of rail, or otherwise appeared to be unusual or extreme conditions. FHWA's assessment was that 13 of these cases (4 fatal crashes, 4 injury crashes, and 5 of unknown severity) involved the ET-Plus 4-inch.

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Page last modified on July 11, 2016
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