**Analysis of Blind Pedestrian Deaths**

**and Injuries from Motor Vehicle Crashes, 2002-2006**

Christopher Hogan, Ph.D

Direct Research, LLC

226 Glen Ave., SW

Vienna, VA 22180

<chogan@directresearch.com>

Revised June 16, 2008

No funding from any source was received for this analysis.

**Executive Summary**

**Counts and rates of death and injuries.**

-   From 2002 to 2006, on average, five legally blind pedestrians per
    year were killed in motor vehicle accidents in the US (Table 1).

-   From 2001 to 2004, on average, 40 legally blind pedestrians were
    hospitalized as the result of a motor vehicle accident (Table 6).

-   Over this period, the number of legally blind pedestrians who
    received emergency room treatment but were not admitted to the
    hospital was too small to estimate. Based on the accident and death
    rates for all pedestrians, we would have expected to find a further
    20 blind pedestrians with ER treatment but no hospital admission
    (Section 4.3). We found only indirect evidence to validate that.

-   On a per-capita basis, the average legally blind person is *less*
    likely to be killed or hospitalized as a result of being hit by a
    car than the average sighted individual. Legally blind individuals
    accounted for 0.11 percent of deaths and 0.15 percent of
    hospitalizations. But they account for 0.43 percent of the US
    population, or 0.23 percent of the US population under age 80
    (Section 4.4).

**Hybrids and pedestrian deaths.**

-   Over this period, no deaths of legally blind pedestrians involved a
    Prius (Table 3) or any other hybrid vehicle (Table 4).

-   For all US pedestrian deaths (blind and sighted), 11 deaths involved
    a Prius (Table 3). (The Prius was singled out here because it is the
    only model with large production volume that was produced solely as
    a hybrid.) The Prius was no more likely to be involved in a
    pedestrian death than the average passenger vehicle (Table 5),
    accounting for 0.05 percent of registered vehicles and pedestrian
    deaths over this period.

**Causes of blind pedestrian deaths.**

-   Over this period, pickup trucks were the vehicles most commonly
    involved in a blind pedestrian death (Table 3).

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-   For both blind and sighted individuals, only about 10 percent of
    pedestrian deaths were coded as occurring as the result of being
    struck while walking in a crosswalk. The rest occurred in other
    locations or location not coded.

-   More than two-thirds of both blind and sighted pedestrians were
    listed as contributing in some way to the accident.

-   Of those tested, slightly more than one-third of both blind and
    sighted pedestrian decedents tested positive for alcohol.

**Summary**

-   Hybrids appear no more dangerous than other vehicles, in terms of
    all pedestrian deaths.

-   There has been no reported case of a blind pedestrian being killed
    by a hybrid.

-   The legally blind appear less at risk than others, in terms of
    pedestrian deaths per capita.

-   By and large, there appears to be little difference between blind
    and sighted pedestrian in terms of how and why they die in vehicular
    crashes.

**1 Background**

A bill has been introduce in the U.S. House of Representatives, HR 5734,
focusing on hybrids and other motor vehicles that emit less noise than
the typical vehicle. If passed into law, the bill would give the
Secretary of Transportation two years to determine a standard for the
best method for alerting blind pedestrians to the presence of a hybrid
vehicle, and a further two years to require all new vehicles to adhere
to that standard. While focusing on blind pedestrians, the bill suggests
that more noise from hybrids would increase the safety of both blind and
sighted pedestrians.[^1]

The language of the bill establishes a clear viewpoint on the issue. Two
sections are worth quoting. First, there is an assumption that hybrids
currently are dangerous:

" ... when operating on their electric engines, hybrid vehicles cannot
be heard by blind people and others, rendering such vehicles **extremely
dangerous** \[emphasis mine\] when driving on the street, emerging from
driveways, moving through parking lots, and in other situations where
pedestrians and vehicles come into proximity with each other;"

Second, although the possibility for some other type of solution is left
open, the bill strongly suggests that making hybrids noisier is the
preferred answer.

" ... determine the minimum level of sound emitted from a motor vehicle
that is necessary to provide blind pedestrians with the information
needed to make safe travel judgments ... which method assures the least
reliance by blind and other pedestrians upon technology they must
possess when traveling and thereby provides the greatest amount of
independence and opportunity for spontaneous travel for these
pedestrians."

At the conclusion of the study, the Secretary of Transportation would
issue a standard for all newly manufactured motor vehicles. Two years
after issuance of the standard, all vehicles would be required to meet
the standard. The standard would probably be a minimum level of noise at
all operating speeds, but might conceivably be some other type of
detection system.

**2 Purpose of Study**

This study gathers the basic facts on pedestrian deaths and injuries in
the US. How many blind pedestrians have been killed by hybrid vehicles
in the US? How many pedestrians, blind or sighted, have been killed in
accidents involving hybrids? Are hybrids involved in pedestrian deaths
at a disproportionate rate? Beyond deaths (the event for which the most
detailed data are available), is there any information to suggest that
the blind are more at risk for pedestrian injuries than others?

In other words, are there any facts suggesting that hybrids are more
dangerous to pedestrians, or even to suggest that blind pedestrians are
at greater risk of death and injury than others?

**3 Sources of Data and Methods**

The US Fatality Analysis Reporting System (FARS) captures data on all US
motor vehicle related deaths occurring in areas routinely open to the
public. Data files are available showing the characteristics of the
persons and vehicles involved, and describing each incident.[^2] FARS
data capture whether or not an individual is legally blind in a series
of variables flagging factors that may have contributed to the
accident.[^3] The main portion of this analysis uses the FARS
contributing factor variables to flag legally blind pedestrians.

FARS is the main source of data used here because it provides detailed
information on the vehicle crash. Other sources of data provide less
information on the crash but were used to validate parts of the findings
from FARS.

A related US Department of Transportation system collects data on a
roughly 1 percent sample of all reportable accidents, not just deaths,
called the General Estimates System (GES). However, too few reportable
accidents with blind pedestrians occurred to make those data useful. (In
the 2006 file, only one such accident occurred in the GES sample.).

The Healthcare Cost and Utilization Project (HCUP) data from the Agency
for Healthcare Research and Quality (AHRQ) provides a roughly
one-in-five sample of all US short-term general hospital discharges. The
HCUP data were used to verify that the serious injury rate for blind
pedestrians is roughly proportion to the death rate. (That is, focusing
solely on deaths, where the vehicle information is available, does not
appear to provide a distorted picture of vehicle accidents involving
blind pedestrians). [^4] In the HCUP data, pedestrian accidents and
blindness are both captured by diagnosis codes reported on the hospital
discharge abstracts.

This analysis also looked, without analytical success, in several
databases that might capture injuries that did not require
hospitalization. None of the data sources examined in that area provided
a reliable estimate of the number of blind pedestrian injuries, largely
due to the very small number of blind pedestrians injured each year. Of
these, only the AHRQ State Emergency Department Databases (SEDD) seemed
worthy of any future followup in this regard. (Proper analysis of the
SEDD would require applying for and purchasing the numerous individual
SEDD component databases.)

The Centers for Disease Control (CDC) Wonder system was used to query US
death certificate data to check the FARS counts of vehicle-related
pedestrian deaths.[^5]

Counts of various items (number of legally blind Americans, US
population, car registrations) are cited individually when used.

**4 METHODS AND RESULTS**

**4.1 Pedestrian Deaths**

Based on the US FARS data, from 2002 and 2006 the US averaged roughly 5
blind pedestrian deaths from motor vehicle crashes (Table 1). Given the
small numbers involve, the count of blind pedestrian deaths was
remarkably stable from year to year. Legally blind individuals accounted
for roughly a tenth of a percent of all pedestrian deaths over this
period.

  ------------------------- ----------- ----------- ----------- -----------
  **Table 1: U.S.                                               
  Pedestrian Deaths in                                          
  Motor Vehicle Accidents,                                      
  2002-2006**                                                   

                                                                

  Year                      Total       Not Legally Legally     Legally
                                        Blind       Blind       Blind as %
                                                                of Total

  2002                      4,851       4,845       6           0.12%

  2003                      4,774       4,768       6           0.13%

  2004                      4,675       4,669       6           0.13%

  2005                      4,892       4,889       3           0.06%

  2006                      4,784       4,778       6           0.13%

  Five-year average         4,795       4,790       5           0.11%

                                                                

                                                                

  Source: Calculated from                                       
  FARS person-level files,                                      
  2002-2006                                                     
  ------------------------- ----------- ----------- ----------- -----------

As a check, to see whether FARS may miss a significant number of deaths,
deaths were separately tabulated using death certificate data from the
US CDC Wonder system (referenced above). In each overlapping year, death
certificates attribute about 10 percent more total pedestrian deaths
than the FARS system does. However, the CDC data included a large
category of non-specific pedestrian deaths, and so may have included a
somewhat broader range of pedestrian accidents than the FARS data does.
For one small example, driveway backover deaths may be included in the
CDC Wonder data but not in the FARS data, because FARS only includes
accidents in areas routinely accessible to the public. In general,
however, the counts are close enough to suggest that the FARS is missing
little relevant data.

  ------------------------------- ---------------------------------------
  **Table 2: CDC Wonder,          
  Pedestrians Killed in Motor     
  Vehicle Accidents**             

  **Year**                        **Deaths**

  2005                            5652

  2004                            5536

  2003                            5584

  2002                            5640

  Source: Calculated from CDC     
  Wonder compressed mortality     
  file data                       

  Note: Includes a large "not     
  otherwise specified" category   
  of pedestrian deaths with       
  specific attribution to motor   
  vehicles, as well as            
  non-traffic deaths.             
  ------------------------------- ---------------------------------------

The types of vehicles causing pedestrian deaths broadly match the US
distribution of vehicles (Table 3). Slightly more than half (45 percent
out of 80 percent) of passenger vehicles involved in pedestrian
fatalities were cars, slightly less than half were light trucks, SUVs,
and minivans. A Prius was involved in 11 of the pedestrian deaths over
this period, but none of the deaths of legally blind pedestrians.

  -------------------------- --------------- --------- --------- --------- ----------- ---------
  **Table 3: Type of Vehicle                                                           
  Involved in US Pedestrian                                                            
  Deaths, 2002-2006**                                                                  

                                                                                       

  **Type of Vehicle**        **All           **% of    **Not     **% of    **Legally   **% of
                             Pedestrians**   total**   Legally   total**   Blind**     total**
                                                       Blind**                         

  Car                        11,882          45%       11,873    45%       9           32%

  Pickup Truck               4,628           17%       4,618     17%       10          36%

  SUV                        3,476           13%       3,474     13%       2           7%

  Minivan                    1,449           5%        1,446     5%        3           11%

  Subtotal, Passenger        21,435          80%       21,411    80%       24          86%
  Vehicles                                                                             

                                                                                       

  Not passenger vehicle      5,212           20%       5,208     20%       4           14%
  (Bus, Truck, Heavy Van,                                                              
  Motorcycle, Etc.)                                                                    

  Total                      26,647          100%      26,619    100%      28          100%

                                                                                       

  Memo: Toyota Prius         11                        11                  0           

  Memo: Prius as % of pass.  0.05%                                                     
  vehicles                                                                             

  Source: Analysis of FARS                                                             
  data files, 2002-2006.                                                               
  -------------------------- --------------- --------- --------- --------- ----------- ---------

Examination of the cars involved in blind pedestrian deaths over this
period reveals no hybrids were involved in any blind pedestrian deaths
(Table 4). As shown above, the most common class of vehicle involved in
a blind pedestrian death was a pickup truck. (Note, however, that the
differences between sighted and blind pedestrian deaths in Table 3 would
not pass traditional tests of statistical significance.)

We can use the Prius as a proxy for hybrids to determine whether or not
hybrids are more likely to be involved in fatal pedestrian accidents.
The Prius is the only vehicle that can a) be identified as a hybrid
within the FARS data and b) had a large production volume. For other
makes, the FARS file does not distinguish hybrid and non-hybrid
variants, or there are too few cars to allow for a reasonable analysis.

  -------------------------------------------------------- --------------
  **Table 4: Vehicles Involved in US Legally Blind         
  Pedestrian Deaths, 2002-2006**                           

                                                           

  Make/Model                                               Number

  BUIC Roadmaster                                          1

  CHEV Blazer-fullsize/Tahoe                               1

  CHEV Caprice/Impala                                      1

  CHEV Cavalier                                            1

  CHEV Celebrity                                           1

  CHEV CKRV-series Pickup                                  3

  CHEV Lumina                                              1

  FORD E-series Van                                        1

  FORD F-series Pickup                                     2

  FORD Ranger                                              2

  FORD Taurus                                              2

  FORD Windstar                                            1

  GMC CKRV-series Pickup                                   2

  GMC Safari                                               1

  HOND Accord                                              1

  INTL Unk eng loc                                         1

  KW CBE                                                   1

  NISS Frontier                                            1

  Other Vehicle                                            1

  TOYT Minivan/Previa                                      1

  TOYT RAV4                                                1

  VOLV 40 Series                                           1

                                                           

  Source: Tabulated from FARS accident and vehicle files,  
  2002-2006                                                
  -------------------------------------------------------- --------------

The Prius appears neither more nor less likely to be involved in a
pedestrian fatality than any other car. This is an estimate based on
total reported Prius sales over this period, and assumes that all Prius
vehicles sold remained on the road. A Prius was involved in 0.05 percent
of all US pedestrian fatalities over this period, and cumulative Prius
sales averaged 0.05 percent of all US car registrations over this period
(Table 5).[^6]

  -------------------------------------------------------- ------------- --------------
  **Table 5: Prius as a Percent of Registered Cars and                   
  Cars Involved in Pedestrian Deaths, Average 2002-2006**                

                                                                         

  **Year**                                                               **Cumulative
                                                                         US Prius
                                                                         Sales, June
                                                                         Each Year**

  2002                                                                   32,006

  2003                                                                   51,941

  2004                                                                   88,487

  2005                                                                   174,002

  2006                                                                   276,747

  Average, 2002-2006                                                     124,637

                                                                         

  Memo: Total US Registered Passenger Vehicles, 2004       247,421,120   
  (midpoint of time period)                                              

                                                                         

  Memo: Prius as % of registered vehicles, 2002-2006                     0.05%

  Memo: Prius as % of vehicles in pedestrian deaths,                     0.05%
  2002-2006 (from Table 3).                                              

                                                                         

  Source: See text footnote for sources                                  
  -------------------------------------------------------- ------------- --------------

**4.2 Pedestrian hospitalizations**

It is reasonable to ask whether the detailed information on blind
pedestrian deaths provides an adequate picture blind pedestrians'
relative risks. On the one hand, does the FARS coding accurately capture
the legally blind status of pedestrians? That is, could FARS undercount
blind pedestrian deaths? On the other hand, could blind pedestrians
suffer disproportionately from non-fatal injuries, so that the FARS
death data under-represent the overall risk? While there are fewer than
5000 pedestrian deaths every year, there are at least 60,000 reportable
pedestrian motor vehicle injuries each year, so focusing solely on
deaths clearly looks only at a fraction of the total risk.[^7]

The only other nationwide data source large enough to capture rare
events of this type (blind pedestrian injuries) is the HCUP database
(described above), a sample of roughly 20 percent of all US short-term
general hospital inpatient discharges. There are about 8 million
hospital discharges per year in the database. Using HCUP, cases coded as
pedestrians injured in automobile collisions were identified, using
diagnoses flagging either legally blind or any of several types of
severe visual impairment.

Any analysis of health care claims data will depend on the accuracy of
the coding of the discharge abstracts or claims data. In particular,
this analysis relies on hospitals' use of "E-codes", the portion of the
international classification of diseases that details the causes of
accidents. And, it relies on hospitals propensity to code various forms
of blindness and to code legally blind status, neither of which may
directly affect the health care that was provided or the payment to the
provider.

Despite the potential limitations on coding, the HCUP data largely
validate the FARS deaths data. The HCUP data show an average of about 40
legally blind pedestrians hospitalized for vehicle-related injuries
every year (Table 6). This reported hospitalization rate for legally
blind pedestrians is somewhat higher than the FARS reported death rate
(Table 6). Where FARS showed an average of 0.11 percent of pedestrian
deaths were legally blind individuals, the HCUP database shows 0.15
percent of pedestrian admissions were for persons coded as legally
blind. Thus, if the death experience in FARS understates the true risk
to the blind, the level of understatement is relatively small. Both
death and hospitalization data suggest roughly the same relative risk
for the legally blind compared to the sighted. Finally, for
completeness, it should be noted that some of these hospitalizations
will overlap the FARS fatality counts, when the individuals expired
while in the hospital.

  ------------------ ------------ ------------ ----------- ------------ ---------------------- -----------
  **Table 6: U.S.                                                                              
  Hospitalizations                                                                             
  for Pedestrians                                                                              
  Involved in Motor                                                                            
  Vehicle Accidents,                                                                           
  2001-2004**                                                                                  

                                                                                               

                                                                        **[Percent of          
                                                                        Total]{.underline}**   

  **Year**           **Total**    **Any        **Legally   **Not Blind  **Any Blindness**      **Legally
                                  Blindness    Blind**     or Legally                          Blind**
                                  (Including               Blind**                             
                                  Legally                                                      
                                  Blind)**                                                     

  **Pedestrians in                                                                             
  motor vehicle                                                                                
  accidents**                                                                                  

  2001               23,237       52           \*          23,185       0.22%                  \*

  2002               27,728       75           42          27,653       0.27%                  0.15%

  2003               27,866       53           48          27,813       0.19%                  0.17%

  2004               26,733       94           59          26,639       0.35%                  0.22%

  **Average**        **26,391**   **68**       **38**      **26,323**   **0.26%**              **0.15%**

                                                                                               

  **Pedestrians in                                                                             
  motor vehicle                                                                                
  accidents, died in                                                                           
  hospital**                                                                                   

  2001               962          \*           \*          \*                                  

  2002               1,155        \*           \*          \*                                  

  2003               1,317        \*           \*          \*                                  

  2004               1,327        \*           \*          \*                                  

  **Average**        1,190        \*           \*          \*                                  

                                                                                               

  Source: Analysis                                                                             
  of HCUP National                                                                             
  Inpatient Sample                                                                             
  Files, 2001-2004                                                                             

  Notes: \* Data                                                                               
  suppressed to                                                                                
  comply with AHRQ                                                                             
  privacy guidelines                                                                           
  \-- too few                                                                                  
  observations to                                                                              
  publish.                                                                                     
  ------------------ ------------ ------------ ----------- ------------ ---------------------- -----------

**4.3 Attempts to quantify pedestrian injuries not requiring
hospitalization**

This section details several failed analyses that tried to estimate the
rate of injuries to blind pedestrians that were not fatal and did not
result in hospital inpatient admission. The main conclusion is that
blind pedestrian injuries are rare enough that samples of accident
reports are inadequate to characterize them. In addition, diagnosis
coding on outpatient visits does not appear good enough to capture the
"E-codes" (described above) for flagging such injuries.

The General Estimates System is analogous to the FARS, but contains data
on a roughly 1 percent sample of all reportable traffic accidents. With
a one-in-one hundred sample, the GES was unlikely to have enough cases
to provide a reliable estimate of blind pedestrian accidents. On
average, for all cases, the NHTSA data suggest that there are roughly 12
reportable injuries for pedestrians for every pedestrian death. For the
five blind pedestrian decedents per year, based on averages for all
pedestrians, one would therefore expect roughly 60 blind pedestrian
injuries total, or an average of 0.6 cases per year in the 1 percent
sample GES data. A cursory analysis of the 2006 GES and found only one
accident involving a blind pedestrian, which appears to validate that.
The GES sample is too thin to address this issue.

It is worth emphasizing why the GES is in adequate. *It is inadequate
for this issue because we expect to see only about 60 reportable
accidents involving blind pedestrian injuries per year, based on the
number of blind pedestrian deaths.* Clearly, this rules out essentially
every sample data source available, for looking at blind pedestrian
injuries.

Medicare claims data provide an alternative data source. Although
Medicare claims are only available for the disabled and elderly,
extracts of large samples of the claims data are available with only
modest data use restrictions. So, while the file is not ideal, it does
have the scope to be able to identify those rare events.

Using Medicare calendar year Outpatient Prospective Payment System
(OPPS) claims, the number of hospital outpatient claims for pedestrian
accidents for the blind were counted using the diagnosis codes and
"E-codes" on those claims. (In this file, emergency department and
outpatient claims are combined). Unfortunately, it largely appears that
hospitals typically don't bother to report the E-codes, or,
alternatively, that most elderly pedestrians injured in automobile
accidents are subsequently admitted to the hospital.

The OPPS file yielded just 628 total outpatient visits for pedestrian
accidents, of which one was for a legally blind pedestrian (two were for
persons with any blindness coded). For what it is worth, that legally
blind pedestrian accounted for 0.15 percent of all Medicare emergency
visits for injured pedestrians. Clearly, despite the fact that the data
are the universe of visits (no sampling error), and even assuming that
under-coding of E-codes is uniform for blind and non-blind pedestrians,
that information has to be put in the context of reflecting a single
claim. That said, it is completely consistent with the fraction of
deaths and hospitalizations for legally blind pedestrians.

The only conclusion that can be drawn from available non-death
non-hospital-admission data is that the number of treatable injuries
from blind pedestrian accidents that do not involve a hospitalization is
probably is quite small. Roughly speaking, there should be perhaps 60
reportable accidents involving blind pedestrian injuries each year
(assuming the ratio of injuries to deaths for the blind is similar to
that for the sighted). Of those, a count of hospitalizations accounts
for roughly 40 per year. That would leave another 20 or so reportable
injuries for blind pedestrians not resulting in admission. That is far
too few to find in most sample databases. A scan of Medicare 2006
outpatient claims reveals a general under-coding of accident codes
("E-codes"). Yet, legally blind pedestrians constituted 0.15 percent of
the Medicare claims for outpatient care, the same as their proportion of
inpatient admissions. (In other words, yet again, the ratio of legally
blind to total pedestrian deaths from the FARS data appears to be
roughly correct for emergency department visits as well.) This again
suggest that the number of emergency visits not resulting in
hospitalization really is as small as was been estimated, perhaps on the
order of 20 visits per year.

The only other data source that might plausibly be able to address this
issue is the AHRQ State Emergency Department Databases (SEDD), a
collection of all emergency department visits from several states.
Unfortunately, the online query system for the SEDD would not allow a
complex query of this type, and the analyst would have to purchase the
several separate state databases to do the analysis. Thus, the SEDD is a
potential data source for this issue that was not fully examined here.

**4.4 Blind and sighted pedestrian accident rates per capita**

This section provides a crude calculation of relative risk for
pedestrian injury for the legally blind and sighted US populations. That
is, in this section, we ask whether US legally blind individuals, on
average, are more or less likely than the sighted individual to injured
as a pedestrian.

First, one major caveat. We cannot accurately asses the risk of being a
legally blind pedestrian without accurate information on the amount of
time spent in that activity. That is, ideally, we would like to
calculate expected deaths or injuries per person-year or per hour of
that activity. Legally blind individuals might walk more or less than
the typical sighted person, so that the number of persons involved may
not be a good proxy for the actual time spent at risk. In particular, it
is worth noting that US legally blind individuals are highly
concentrated among the oldest old (those over age 80, see below), who
may or may not be capable of independent ambulation.

It is nevertheless reasonable to do what analysis we can (per person),
and to keep this caveat in mind. The only risk rate we can calculate is
per person, comparing the blind's proportion of deaths and injuries
above to the blind's proportion of the population (calculated below).

How many legally blind US residents are there? A 2004 estimate from the
US National Eye Institute (of the National Institutes of Health) showed
roughly 937,000 Americans age 40 or older were legally blind. Of those,
648,000 were age 80 and older.[^8] But that estimate is not the entire
US adult population, only those age 40 and over. The American Foundation
for the Blind (AFB), by contrast, cites a 10-year-old estimate of
roughly 1.3 million legally blind Americans of all ages.[^9] Starting
from that estimate, and ignoring population growth over the last ten
years, should provide a reasonable basis for calculating per-capita risk
rates.

Using the AFB estimate, 0.43 percent of the US population is legally
blind. Even netting out the oldest old (those over age 80), 0.23 percent
of the US under-80 population is legally blind. Based on this crude
measure (per person, not per hour walked), pedestrian activity does not
appear particularly risky for the legally blind. Their fraction of
pedestrian deaths (0.11 percent) and hospitalizations (0.15 percent) is
smaller than their fraction of the US population, even if the oldest old
are excluded.[^10]

Many factors might reasonably account for this. The legally blind may be
less likely to be pedestrians, or might be significantly more cautious
than others. The FARS provided little insight into this issue due to the
small number of observations.

Age does not appear to explain the below-average rate of pedestrian
deaths for the legally blind. The incidence of pedestrian deaths rises
with age, from 2 incidents per 100,000 for those age 20-24 to 4
incidents per 100,000 persons for those age 85 and older (calculated
from CDC Wonder, cited above.) But the FARS data show that the average
legally blind pedestrian decedent was *older* than sighted pedestrian
decedents (58 years versus 45 years). By itself, that suggests the
legally blind ought to have an *above-average* rate of pedestrian
deaths, instead of below-average.

Beyond. that, the FARS suggests little difference between blind and
sighted pedestrian decedents. In both cases, only a tiny minority of
fatal accidents occurred to pedestrians in crosswalks (11 percent for
the blind versus 9 percent for the sighted). Similarly, the majority of
decedents were listed as contributing to the accident in some fashion
(for example, "improper crossing"), with 74 percent of blind decedents
and 62 percent of sighted decedents so noted. Finally, there appeared to
be little difference in alcohol use when that was noted. Among those
tested, 37 percent of both blind and sighted pedestrian decedents tested
positive for alcohol.

**5 SUMMARY, INTERPRETATION, CAVEATS**

This research turned up no evidence to support the hypothesis that
hybrids are more dangerous than other cars, either to blind pedestrians
or to pedestrians in general. The best-selling US hybrid, the Prius, was
neither more nor less likely than average to be involved in a pedestrian
death. Instead, its rate of involvement in all pedestrian deaths over
this period exactly matched its prevalence among all registered US
passenger vehicles over this period.

This is clearly not a pure measurement, in the sense of a controlled
experiment. The observed data will reflect both the characteristics of
the car and those of the typical driver. However, it does put an upper
bound on any additional risk that persons can reasonably impute to
hybrids. Given the hundreds of thousands of Prius vehicles on the road
today, if they were significantly more dangerous than average, that
should have shown up in the data.

In short, the raw data suggest that hybrids are no more dangerous than
average, and even a more sophisticated perspective on the data says
that, at the minimum, they could not possibly be much more dangerous
than average.

For blind pedestrians, there are so few reported accidents that it is
difficult to make many definitive statements. But that, in and of
itself, is a relevant fact. In discussing this issue, we should note
that, as estimated here, accidents with blind pedestrians result in an
average of five deaths, 40 hospitalizations, and a (weakly estimated) 20
additional emergency room visits not requiring hospitalization. That is
the extent of the current problem, and it is the potential expansion of
that problem that the proposed legislation is attempting to address.

By and large, the circumstances surrounding blind pedestrian deaths
appear similar to those of sighted pedestrian deaths. Only a small
minority of either blind or sighted pedestrian decedents were in a
crosswalk at the time of accident. Rates of alcohol use and rates of
behavior cited as contributing to the accident were roughly similarly
for blind and sighted pedestrian decedents. The only notable difference
from the FARS data is that blind pedestrian decedents were older, on
average, than sighted pedestrian decedents.

Legally blind individuals appear less likely than others to be killed or
hospitalized as a result of being hit by a vehicle. Whether this is
because they have lower exposure (spend less time as pedestrians) or are
more cautious is impossible to determine from the data examined here.

One final caveat regards coding of the data. It is always possible that
the data simply do not reflect the true underlying rates, due to
mis-coding. In this case, however, the data were remarkably consistent
across completely different sources. FARs, HCUP, and Medicare claims all
suggest that blind pedestrians account for between 0.11 and 0.15 percent
of pedestrian deaths and injuries. Although that does not eliminate
coding concerns, it provides some comfort that miscoding does not
provide a gross under-estimate of the problem.

Together, the facts suggest that the Congress should move with caution
in mandating noise-making or other devices on hybrid and electric
vehicles. First, as detailed above, there is no hard evidence of any
problem. Second, there appears to be little qualitative difference
between blind and sighted pedestrian decedents, other than the generally
lower per-capita rate of death and injury for the legally blind. Third,
the current number of blind pedestrian deaths and hospitalizations is
small, while the number of cars to be modified is large and growing.
Even a modest cost per vehicle may result in a very large cost per
putative life saved.

Ideally, lawmakers should strive to judge the costs and benefits.

On the one hand, the US has a significant problem with oil use and all
that implies -- for US national security, for our balance of payments,
for the functioning of our economy, and for the potential harm from
global warming. These are real, genuine, and to a large degree
documented problems that are know to be issues right now, and known to
be affecting the well-being of almost all Americans. Hybrids and other
more efficient forms of transportation are part of the solution to those
current, well-understood, and widely shared problems. And hybrids are
being adopted as a part of the solution world-wide. The US is moving in
tandem with the rest of the developed world in this regard.

On the other hand, we have an allegation of potential harm for blind
Americans. In the US, no blind pedestrian has been killed by a hybrid.
Fundamentally, the Congress is making policy on the basis of anecdotes.
At this time, all available evidence suggests that hybrids are no more
hazardous than other vehicles to pedestrians in general. For the blind,
current level of deaths and hospitalizations from pedestrian accidents
is quite small. The per-capita rate of death and hospitalization from
pedestrian accidents is lower for the legally blind than for the
sighted. And the circumstances of their pedestrian deaths and injuries
appear no different from the sighted.

So it boils down to this: Does the Congress want to take hybrids, one of
the most promising solutions to our energy problems, and make them just
a little bit less acceptable to the average buyer? Does the Congress
want to take our urban areas and make them just a bit noisier? All in
order to solve a problem that may or may not actually exist, for a small
subset of the population? The Congress should ask for hard evidence of
actual current harm and risk from quiet cars before proceeding down this
path. As far as this analysis has shown, no such evidence exists.

[^1]: As of 4/21/2008, the text of the bill could be read at this URL at
    the Library of Congress:

    <http://thomas.loc.gov/cgi-bin/query/D?c110:1:./temp/~c110VCcZOD::>

[^2]: An overview of FARS can be found here:
    <http://www-nrd.nhtsa.dot.gov/departments/nrd-30/ncsa/FARS.html>

[^3]: A person is legally blind if vision is 20/200 or worse with
    correction, or if field of view is limited to 20 degrees or less.

[^4]: An overview of HCUP can be found here:
    <http://www.ahrq.gov/data/hcup/>

[^5]: CDC Wonder can be accessed here:
    <http://wonder.cdc.gov/mortSQL.html>

[^6]: Sources: Total US passenger vehicles:

    <http://en.wikipedia.org/wiki/Passenger_vehicles_in_the_United_States#Total_number_of_vehicles>

    Total US cumulative Prius sales:

    <http://www.automotive-usenet.com/alt-autos-lexus/4198-toyota-lexus-hybrid-unit-sales-history-usa.html>

[^7]: National Highway Transportation Safety Administration,
    Transportation Safety Facts 2006, Pedestrians, publication number
    DOT HS 810 810.
    [http://www.nhtsa.dot.gov/portal/nhtsa_static_file_downloader.jsp?file=/staticfiles/DOT/NHTSA/Traffic%20Injury%20Control/Articles/Associated%20Files/TSF2006_810810.pdf](http://www.nhtsa.dot.gov/portal/nhtsa_static_file_downloader.jsp?file=/staticfiles/DOT/NHTSA/Traffic Injury Control/Articles/Associated Files/TSF2006_810810.pdf)

[^8]: . Taken from the National Eye Institute of the National Institutes
    of Health, URL <http://www.nei.nih.gov/eyedata/pbd_tables.asp>. The
    original source was published in the Archives of Ophthalmology,
    Volume 122, April 2004.

[^9]: The American Foundation for the Blind cites a decade-old estimate
    of 1.3 million. Adjusted for population growth, that would yield
    slightly over 1.4 million currently. The citation can be found at:
    <http://www.afb.org/Section.asp?SectionID=15&DocumentID=1367>. The
    original data source for that estimate was the National Center for
    Health Statistics, National Health Interview Survey - Disability
    Supplement, 1994 and 1995.

[^10]: There is no way properly to use the National Eye Institute number
    for this calculation without considerably more work, because we
    would have to exclude the under-40 population from the decedent and
    hospitalization data. If we simply took the NEI data as the entire
    denominator, the blind would account for 0.31 percent of the
    population. It is also worth noting that the NEI data show a much
    larger pool of persons with low vision. Hence, any mis-reporting of
    persons with low vision as legally blind, in FARS or HCUP, could
    plausibly have boosted the apparent accident and hospitalization
    rate for the legally blind.