AN ANALYSIS ON FARS DATA

OVER A PERIOD OF 15 YEARS

(1998 to 2012)(Traffic Safety Term Paper)

GROUP

Abhinav Mishra

Akash Chandra

Anurag Singhal

Dileep Lachheta

Mayank Agarwal

Prabhat K. Ravi

Rocky Kasana

INTRODUCTION

In the current research alcohol consumption has been studied & for deep insight data has been divided into following categories

Blood Alcohol Concentration Data Type Name

All (irrespective of BAC) Type-I

0.01g/dLto 0.94+g/dL Type-II

0.01g/dLto 0.08g/dL Type-III

0.08g/dL to 0.94g/dL Type -IV

PARAMETERS CONSIDERED

Age

Sex

Number of Occupants

Restraint System Used

Crash Time

Ethnicity

Roadway Function Class

Statistical Analysis: Mann-Whitney

Test

What is it for? A non-parametric test to compare the central tendencies of two groups

It assumes Random assignments to groups

Test statistic: U

Based on ranks from two independent

samples, they correspond to

i. the t test for two independent samples,

except that no assumptions

ii. are necessary regarding normality ore

equality or variances

Mann-Whitney Test: Procedure

Rank all scores together, ignoring

which group they belong

Separately sum the ranks for the first and

second samples

Select the larger of these two rank

totals, and call it TX

Sample Null hypothesis

The two groups

are the same

Null distribution

U (Ustatic with n1, n2)compare

How unusual is this test statistic?

P < 0.05 P > 0.05

Reject Ho Fail to reject Ho

Mann-Whitney U test

Test statistic

U1 or U2

Mann-Whitney U test

Critical Values for 1 and 2 Tail Tests

2 Tail

Confidence.

1 Tail

Confidence UCritical U < U Critical

80.0% 90.00% 200 YES

90.0% 95.00% 192 YES

95.0% 97.50% 184 YES

99.0% 99.50% 171 YES

Assume Ustatic=120

AGE

FARS data is divided into different age groups

namely

under 20

20 to 29 years

30 to 39 years

40 to 49 years

50 to 59 years

60 years and above

Year All Crashes % Drop Year Crashes % Drop

1998 99755 1998 12414

1999 99311 -0.45 1999 12300 -0.93

2000 99431 0.12 2000 12563 2.09

2001 99756 0.33 2001 12653 0.71

2002 100403 0.64 2002 13168 3.91

2003 100562 0.16 2003 12908 -2.01

2004 99487 -1.08 2004 12301 -4.93

2005 99873 0.39 2005 12854 4.30

2006 96949 -3.02 2006 12935 0.63

2007 93045 -4.20 2007 13477 4.02

2008 83355 -11.62 2008 12858 -4.81

2009 75557 -10.32 2009 11726 -9.65

2010 68217 -10.76 2010 9878 -18.71

2011 66433 -2.69 2011 9305 -6.16

2012 68457 2.96 2012 8675 -7.26

All Crashes (TYPE - I) Persons with positive BAC (TYPE - II)

Year Crashes % Drop

1998 2165

1999 2114 -2.41

2000 2228 5.12

2001 2287 2.58

2002 2245 -1.87

2003 2255 0.44

2004 2103 -7.23

2005 2117 0.66

2006 2245 5.70

2007 2281 1.58

2008 2067 -10.35

2009 1877 -10.12

2010 1689 -11.13

2011 1524 -10.83

2012 1445 -5.47

Year Crashes % Drop

1998 10249

1999 10186 -0.62

2000 10335 1.44

2001 10386 0.49

2002 10923 4.92

2003 10653 -2.53

2004 10198 -4.46

2005 10737 5.02

2006 10690 -0.44

2007 11196 4.52

2008 10791 -3.75

2009 9849 -9.56

2010 8189 -20.27

2011 7781 -5.24

2012 7230 -7.62

Type-III Type-IV

Percentage Change Year-wise

0

5000

10000

15000

20000

25000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f Fa

talitie

s

Year

Under 20

20-29

30-39

40-49

50-59

over 59

under 20

20-29

30-39

40-49

50-59

over 59

Type –I v/s Type –II for Age

Variations in fatality with age for data Type I & II

OBSERVATIONS (TYPE 1 & TYPE II)

Younger persons are more involved in crashes in

comparison to older persons

In Type-II data, number of fatalities are more for

person with age between 20 & 29. This may be due

to 21 year minimum drinking age law

In both cases there is decrease in fatalities after 2007

which may be due to change in enforcement.

For type-I data, graph shows that there is decrease in

fatalities with persons involving age less than 20 after

2004 while there is increase in crashes with person

age group between 20 & 29.

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f Fa

talit

ies

Year

Under 20

20-29

30-39

40-49

50-59

over 59

Under 20

20-29

30-39

40-49

50-59

Over 59

Type –IV v/s Type –III for Age

Variations in fatality with age for data type III & IV

OBSERVATIONS (TYPE III & TYPE IV)

In both cases persons in age group of 20-29 are

much more involved in crashes in comparison to

any other age group

Fatalities for each age group face a sharp

decrease after 2007 which may be result of

certain measures of enforcement.

Fatalities involving persons with BAC within limit are

not changing much with time but have

decreased by a small value after 2007

NUMBER OF OCCUPANT

In order to see the variation for different types of vehicles

the data has been divided into following groups

One

Two

Three to six

More than six

Variations in fatality with number of occupant for data type I & II

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f Fa

ralitie

s

Year

No. of Occupants

Data Type I & Type II

1 2 3 to 6 More than 6 1 2 3 to 6 more than 6

OBSERVATIONS (TYPE 1 & TYPE II)

Numbers of fatalities are not changing much after 2010 in all crashes specifically in alcohol related crashes.

People are less likely to drink when they travel in group of six and more (may be public vehicle!)

Number of fatalities with number of occupants 1 are very high in comparison to fatalities with number of occupants greater than one. It might be possible due to two reasons.

Fraction of persons travelling alone is more

People tend to drive more carelessly if they are travelling alone

0

1000

2000

3000

4000

5000

6000

7000

1998 2000 2002 2004 2006 2008 2010 2012

Nu

mb

er

of Fa

talitie

s

Year

No. of Occupants

Data type IV & type III

1 2 3 to 6 More than 6 1 2 3 to 6 More than 6

Variations in fatality with number of occupant for data type IIII & IV

OBSERVATIONS (TYPE III & TYPE IV)

Fatalities are more for data type-IV as

compared to data type-III

Number of fatalities with number of occupants

one are very high in comparison to fatalities

with number of occupants greater than one.

Numbers of fatalities are not changing much

with time for crashes involving persons with

BAC within limit

Although numbers of fatalities are

approximately same for people with BAC

within limit and above limit visually but

statistically they are different.

GENDER VARIATION

How many Males and Females actually drive on U.S.

Roads?

The percent of licensed drivers that are males

declined with time from 52.4 percent in 1983 to 50.3

percent in 1997.

It then leveled off because females had become 50

percent of the drivers.

Presently almost equal numbers of male and female

drivers are present on U.S. roads.

OBSERVED TRENDS

All fatalities vs fatalities under the influence of alcohol

for both male and female

0

10000

20000

30000

40000

50000

60000

70000

1998 2000 2002 2004 2006 2008 2010 2012

Nu

mb

er o

f F

ata

liti

es

Year

Type 1 vs Type 2 Data

Male Female Male Female

OBSERVATIONS

Number of fatalities both among male and female

had taken a significant plunge after 2006.

Number of fatalities which were recorded under the

influence of alcohol had remained almost same and

had decreased only after 2010.

0

10000

20000

30000

40000

50000

60000

70000

1998 2000 2002 2004 2006 2008 2010 2012

Nu

mb

er o

f F

ata

liti

es

Year

Type 1 vs Type 2 Data

Male Female Male Female

OBSERVATIONS

Male drivers continue to surpass women in the number

of alcohol-involved fatal crashes

That is why after enforcement of stricter laws a higher

decrease is observed among the male gender after

2010.

0

10000

20000

30000

40000

50000

60000

70000

1998 2000 2002 2004 2006 2008 2010 2012

Nu

mb

er o

f F

ata

lit

Year

Type 1 vs Type 2 Data

Male Female Male Female

OBSERVED TRENDS

Fatalities of drivers within the legal limit vs. beyond the

legal limit of BAC for both male and female

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f Fa

talit

ies

Year

Type 3 v/s Type 4 Data

Male Female Male Female

OBSERVATIONS

The numbers of male driver fatalities that drive after

drinking beyond the legal limit are considerable higher

than the number of females.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f Fa

talit

ies

Year

Type 3 v/s Type 4 Data

Male Female Male Female

OBSERVATIONS

With the increase in the blood alcohol concentration

the number of fatalities in both male and female

increases.

There has been a considerable decrease in the

number of male deaths after 2008

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f Fa

talit

ies

Year

Type 3 v/s Type 4 Data

Male Female Male Female

Factors responsible for this decrease

over the years

Enforcement of Zero Tolerance laws that establish

maximum legal BAC limit of .02 for those under 21

years of age while operating a motor vehicle

Laws that provide for administrative license revocation

or suspension prior to conviction for driving under the

influence

Laws that set the minimum legal drinking age to 21

Laws that define a blood alcohol concentration

above a specified threshold as sufficient evidence of

“driving under the influence”

CRASH TIME

Entire period of 24 hours was divided the into four sub-

segments:-

00:00 AM to 05:59 AM

06:00 AM to 11:59 AM

12:00 PM to 05:59 PM

06:00 PM to 11:59 PM

OBSERVED TRENDS

All fatalities vs. those under the influence of alcohol

0

5000

10000

15000

20000

25000

30000

35000

40000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f fa

talitie

s

Year

Crash Time

00 to 6 AM 6 AM to 12 PM 12 PM to 6 PM 6 PM to 12 AM

00 to 6 AM 6 AM to 12 PM 12 PM to 6 PM 6 PM to 12 AM

Type II

Type I

OBSERVATIONS

Influence of alcohol was recorded more in the 12 hour

span of 6PM to 6AM than its other half.

This points that people under the influence of alcohol

are higher in number during the night time and they

had more likelihood of getting involved in a crash.

0

5000

10000

15000

20000

25000

30000

35000

40000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f fa

talitie

s

Year

Crash Time

00 to 6 AM 6 AM to 12 PM 12 PM to 6 PM 6 PM to 12 AM

00 to 6 AM 6 AM to 12 PM 12 PM to 6 PM 6 PM to 12 AM

Type I

Type II

OBSERVATIONS

General fatality trend points more deaths in the 12

hour span of 12PM to 12AM but the number of people

dying due to alcohol involvement are still higher in 6PM

to 6 AM span.

For a particular year say 2009, overall on an average

one alcohol-impaired-driving fatality has occurred

every 48 minutes. However, these fatalities did not

occur evenly throughout the day.

In 2009, from midnight to 3 a.m., two-thirds of fatal

crashes involved an alcohol-impaired driver which is

twice the overall average.

OBSERVED TRENDS

Fatalities of drivers within the legal limit vs. beyond the

legal limit of BAC

0

1000

2000

3000

4000

5000

6000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f fa

talitie

s

Year

Crash Time

00 to 6 AM

6 AM to 12 PM

12 PM to 6 PM

6 PM to 12 AM

00 to 6 AM

6 AM to 12 PM

12 PM to 6 PM

6 PM to 12 AM

Type III

Type IV

OBSERVATIONS

Number of fatalities of people drunk within the legal

limit of BAC less than .08 were lesser and most of them

were observed in the time group 6 PM to 12 AM.

The percentage of alcohol-impaired drivers involved

in fatal crashes by time of day also remains consistent

from year to year.

OBSERVATIONS NHTSA (DOT HS 811 523)

“Time of Day and Demographic Perspective Of Fatal

Alcohol-Impaired-Driving Crashes”

This behaviour was consistent with our analysis for all the years.

RESTRAINT SYSTEM USED

Analysis under this category is carried out

considering the usage of Restraint System

Restraint System Used

Restraint System Not-Used

Restraint System Improperly Used

0

10000

20000

30000

40000

50000

60000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f F

ata

litie

s

Year

Restraint System Use

Data Type-I & Type-II

Not used Used Improperly used Not used Used Improperly used

Variations of fatalities with restraint system use for data Type-I & II

OBSERVATIONS (TYPE 1 & TYPE II)

For type I case, there were less fatalities when restraint

system was not used as compared to the fatalities when

restraint system was used.

Whereas in Type II case, the trend is opposite.

So, use of restraint system played a major role in reducing

fatalities in alcohol related cases.

For both types I and II, the number of fatalities reduced

with time specifically in the case when restraint system

was not used.

This is possibly because restraint system use didn’t play a

major role as compared to other factors like enforcement

laws, increased awareness of people etc.

In recent years (since 2010), the number of fatalities has

not changed much.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

1998 2000 2002 2004 2006 2008 2010 2012

Nu

mb

er

of fa

talitie

s

Year

Restraint System Use

Data Type-III & Type-IV

Not used Used Improperly used Not used Used Improperly Used

Type IV

Type III

Variations of fatalities with restraint system use for data Type-III & IV

OBSERVATIONS (TYPE III & TYPE IV)

For Type III case, there is considerable difference

between the number of fatalities when restraint

system was used and when that was not used.

However, there is not much difference between the

number of fatalities when restraint system was used

and when that was not used in Type IV case.

The number of fatalities has slightly increased over

time when restraint system was used.

The reason for this observation might be that people

who had taken alcohol were less concerned with

traffic safety when they have used restraint system.

ROADWAY FUNCTION CLASS

For analysis in present study, this is divided into

following categories

Rural Interstate

Rural Others

Urban Interstate

Urban Others

0

1000

2000

3000

4000

5000

6000

7000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f P

ers

on

s

Year

Roadway Function Class (Type III vs Type IV)

Rural Interstate

Others

Urban Interstate

Others

Rural Interstate

Others

Urban Interstate

Others

Variations in fatality with roadway-function class for data type III& IV

Observations

For both the cases Types III and IV, fatalities

on rural roadways were more than fatalities

on urban roadways.

Number of fatalities occurred on interstates

roadways was lesser than that in other

roadways due to better infrastructure and

traffic safety measures provided on

interstates road.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

1998 2000 2002 2004 2006 2008 2010 2012

No

. o

f Fa

talitie

s

Year

Ethinicity

Hispanics

Others

Hispanics

Others

Red- Type 4Blue- Type 3

Variations in fatality with sex for data Type-III & IV

Conclusions Sharp decrease in number of fatalities in all the

crashes and also those influenced with alcohol especially during the latest years from 2008

Male drivers continue to surpass women in the number of alcohol-involved fatal crashes and after enforcement of stricter laws a higher decrease is observed among the male gender especially after 2010

the number of fatalities with number of occupants one are very high in comparison to fatalities with number of occupants greater than one which indicates that people tend to drink above limit and drive when they are only occupants of vehicle

fatalities that were due to the influence of alcohol were recorded more in the night 12 hour span of 6PM to 6AM than its other half