# Weather-Related Crashes on U.S. Highways in 2001

Lynette C. Goodwin

Mitretek Systems, Inc.

December 19, 2003

## INTRODUCTION

This paper summarizes 2001 crashes, crash fatalities and crash injuries
on U.S. highways that occurred in adverse road weather conditions. Crash
data were obtained from National Highway Traffic Safety Administration
(NHTSA) databases, including the General Estimates System (GES) and the
Fatality Analysis Reporting System (FARS). The GES derives totals from
sample estimates rather than direct counts.

Weather-related crashes are defined as those crashes that *occur* in the
presence of adverse weather or slick pavement. It should be noted that
these conditions may not necessarily be the *cause* of weather-related
crashes. Crash data cover all types of vehicles including passenger
cars, light trucks (e.g., pickups, vans), large trucks (e.g., tractor
tailors), motorcycles, buses and other vehicles (e.g., motorhomes). This
paper does not distinguish vehicle types or discuss the number of
vehicles involved in crashes.

**2001 CRASH DATA**

There were over 6,314,000 vehicle crashes on U.S. highways in 2001. Over
22 percent of these crashes were weather-related. Police-reported
crashes, fatalities and injuries are presented in Table 1. In the tables
and figures below "Slick Pavement" includes wet, snowy, slushy, or icy
pavement. "Adverse Weather" includes rain, sleet, snow, fog, (rain and
fog), as well as (sleet and fog). "Other/Unknown Weather" includes smog,
smoke, blowing sand, blowing snow, blowing dust and crosswinds.
"Other/Unknown Pavement" includes pavement with sand, dirt and oil.

**Table 1 -- 2001 Crashes, Fatalities and Injuries by Weather and
Pavement Condition**

+-------------------------------+-------+----+-----+-----+------+----+
|                               | *     |    | **  |     | **P  |    |
|                               | *Vehi |    | Per |     | erso |    |
|                               | cle** |    | son |     | ns** |    |
|                               |       |    | s** |     |      |    |
|                               | *     |    |     |     | **I  |    |
|                               | *Cras |    | *   |     | njur |    |
|                               | hes** |    | *Ki |     | ed** |    |
|                               |       |    | lle |     |      |    |
|                               |       |    | d** |     |      |    |
+-------------------------------+-------+----+-----+-----+------+----+
| Total                         | 6,31  |    | 42, |     | 3    |    |
|                               | 4,056 |    | 116 |     | ,032 |    |
|                               |       |    |     |     | ,673 |    |
+-------------------------------+-------+----+-----+-----+------+----+
| Non-Adverse Conditions        | 4,90  | 7  | 35, | 83  | 2    | 7  |
|                               | 5,559 | 7. | 198 | .6% | ,417 | 9. |
|                               |       | 7% |     |     | ,244 | 7% |
+-------------------------------+-------+----+-----+-----+------+----+
| **Adverse Road Weather        | 1,40  | 2  | 6,  | 16  | 615  | 2  |
| Conditions**                  | 8,496 | 2. | 918 | .4% | ,429 | 0. |
|                               |       | 3% |     |     |      | 3% |
+-------------------------------+-------+----+-----+-----+------+----+
| **Slick Pavement & Clear      | 48    | 3  | 2,  | 31  | 222  | 3  |
| Weather**                     | 4,449 | 4. | 204 | .9% | ,645 | 6. |
|                               |       | 4% |     |     |      | 2% |
+-------------------------------+-------+----+-----+-----+------+----+
| **Slick Pavement &            | 1     | 0. | 46  | 0   | 3    | 0. |
| Other/Unknown Weather**       | 1,182 | 8% |     | .7% | ,543 | 6% |
+-------------------------------+-------+----+-----+-----+------+----+
| **Slick Pavement & Adverse    | 89    | 6  | 4,  | 61  | 379  | 6  |
| Weather**                     | 2,835 | 3. | 264 | .6% | ,001 | 1. |
|                               |       | 4% |     |     |      | 6% |
+-------------------------------+-------+----+-----+-----+------+----+
| **Other/Unknown Pavement &    | 300   | 0. | 9   | 0   | 1    | 0. |
| Adverse Weather**             |       | 0% |     | .1% | ,236 | 2% |
+-------------------------------+-------+----+-----+-----+------+----+
| **Dry Pavement & Adverse      | 1     | 1. | 395 | 5   | 9    | 1. |
| Weather**                     | 9,731 | 4% |     | .7% | ,003 | 5% |
+-------------------------------+-------+----+-----+-----+------+----+

As shown in the table above, over 6,900 people were killed and
approximately 615,000 people were injured in weather-related crashes in
2001. The crash analysis revealed that most weather-related crashes
happen in the presence of rain and wet pavement. Nearly 79 percent of
weather-related crashes occurred on wet pavement and 49 percent happened
during rainfall. Nearly 5,400 people were killed and nearly 511,000
people were injured in crashes on wet pavement. Over 3,200 people were
killed and nearly 309,000 people were injured in crashes during
rainfall.

Twenty percent of weather-related crashes occurred on snowy or slushy
pavement and 13 percent happened during snowfall or sleet. Over 1,100
people were killed and nearly 95,000 people were injured in crashes on
snowy or slushy pavement. During snowfall or sleet there were nearly 790
crash fatalities and nearly 62,000 crash injuries. Only three percent of
weather-related crashes---nearly 44,000---occurred in fog. Over 670
people were killed and over 19,000 people were injured in fog-related
crashes.

Figure 1 depicts crashes on slick pavement. In 2001, more than 1,388,000
crashes occurred on slick pavement. Nearly 80 percent of these crashes
happened on wet pavement. Roughly 12 percent of these crashes occurred
on icy pavement, while 8 percent took place on snowy or slushy pavement.
Over 6,500 persons were killed and more than 605,000 people were injured
in crashes on slick pavement.

Nearly 913,000 crashes happened in adverse weather conditions. As shown
in Figure 2, over 75 percent of these crashes occurred in the rain,
while more than 18 percent took place during snowfall. Approximately
five percent happened in foggy conditions and roughly two percent
occurred in sleet, (rain and fog) and (sleet and fog). More than 4,600
people were killed and over 389,000 people were injured in crashes in
adverse weather.

![](media/image2.wmf){width="3.232638888888889in"
height="2.9256944444444444in"}

Figure 1 -- 2001 Crashes on Slick Pavement

![](media/image3.wmf){width="3.7819444444444446in" height="2.9375in"}

Figure 2 -- 2001 Crashes in Adverse Weather

Crashes by weather and pavement condition are shown in Table 2.
Fatalities and injuries in crashes are summarized by condition in Table
3 and Table 4, respectively.

**Table 2 -- 2001 Crashes by Weather and Pavement Condition**

  -------------- ----------- --------------- ------------- ------------ ------------- ------------ ----------- --------- ------------ ------------ ---------------
                             **Weather                                                                                                             
                             Conditions**                                                                                                          

                             Clear           Rain          Sleet        Snow          Fog          Rain, Fog   Sleet,    Other        Unknown      **Total**
                                                                                                               Fog                                 

  **Pavement     Dry         4,850,722       626           0            146           18,958       0           0         7,900        4,586        **4,882,939**
  Conditions**                                                                                                                                     

                 Wet         381,936         673,601       3,058        24,024        19,529       2,213       275       2,323        1,559        **1,108,518**

                 Snow, Slush 30,145          1,272         2,505        73,835        755          2           79        712          767          **110,072**

                 Ice         72,368          10,096        10,320       69,296        1,581        393         2         3,466        2,355        **169,876**

                 Sand, Dirt, 9,197           101           0            0             0            0           0         2            96           **9,396**
                 Oil                                                                                                                               

                 Other       8,225           0             0            82            4            0           0         64           265          **8,640**

                 Unknown     14,798          0             0            112           1            0           0         0            9,704        **24,615**

                 **Total**   **5,367,391**   **685,696**   **15,882**   **167,495**   **40,828**   **2,608**   **356**   **14,467**   **19,332**   **6,314,056**
  -------------- ----------- --------------- ------------- ------------ ------------- ------------ ----------- --------- ------------ ------------ ---------------

**Table 3 -- 2001 Fatalities by Weather and Pavement Condition**

  -------------- ----------- -------------- ----------- --------- --------- --------- -------- -------- --------- --------- ------------
                             **Weather                                                                                      
                             Conditions**                                                                                   

                             Clear          Rain        Sleet     Snow      Fog       Rain,    Sleet,   Other     Unknown   **Total**
                                                                                      Fog      Fog                          

  **Pavement     Dry         34,638         1           0         4         390       0        0        71        45        **35,149**
  Conditions**                                                                                                              

                 Wet         1,803          3,156       35        117       209       35       5        13        14        **5,387**

                 Snow, Slush 130            12          27        334       4         3        0        1         2         **513**

                 Ice         271            43          80        182       20        0        2        13        3         **614**

                 Sand, Dirt, 41             2           0         0         0         0        0        3         1         **47**
                 Oil                                                                                                        

                 Other       60             0           0         1         4         0        0        5         0         **70**

                 Unknown     71             0           0         1         1         0        0        0         263       **336**

                 **Total**   **37,014**     **3,214**   **142**   **639**   **628**   **38**   **7**    **106**   **328**   **42,116**
  -------------- ----------- -------------- ----------- --------- --------- --------- -------- -------- --------- --------- ------------

**Table 4 -- 2001 Injuries by Weather and Pavement Condition**

  -------------- ----------- --------------- ------------- ----------- ------------ ------------ ----------- --------- ----------- --------- ---------------
                             **Weather                                                                                                       
                             Conditions**                                                                                                    

                             Clear           Rain          Sleet       Snow         Fog          Rain, Fog   Sleet,    Other       Unknown   **Total**
                                                                                                             Fog                             

  **Pavement     Dry         2,402,917       351           0           185          8,468        0           0         4,917       0         **2,416,837**
  Conditions**                                                                                                                               

                 Wet         185,763         302,734       1,722       10,251       6,884        1,827       263       1,231       0         **510,675**

                 Snow, Slush 10,648          637           1,270       23,730       244          0           0         374         0         **36,901**

                 Ice         26,235          4,107         3,242       21,092       921          79          0         1,938       0         **57,613**

                 Sand, Dirt, 4,948           887           0           0            349          0           0         0           0         **6,184**
                 Oil                                                                                                                         

                 Other       4,402           0             0           0            0            0           0         60          0         **4,462**

                 Unknown     0               0             0           0            0            0           0         4,917       0         **0**

                 **Total**   **2,634,913**   **308,715**   **6,234**   **55,257**   **16,866**   **1,906**   **263**   **8,520**   **0**     **3,032,673**
  -------------- ----------- --------------- ------------- ----------- ------------ ------------ ----------- --------- ----------- --------- ---------------

Vehicle crashes in Table 2 are categorized by type in the following
tables. Tables 5 and 6 summarize fatal crashes and injury crashes,
respectively. Table 7 includes property-damage-only crashes.

**Table 5 -- 2001 Fatal Crashes by Weather and Pavement Condition**

  -------------- ----------- -------------- ----------- --------- --------- --------- -------- -------- -------- --------- ------------
                             **Weather                                                                                     
                             Conditions**                                                                                  

                             Clear          Rain        Sleet     Snow      Fog       Rain,    Sleet,   Other    Unknown   **Total**
                                                                                      Fog      Fog                         

  **Pavement     Dry         31,161         1           0         4         335       0        0        61       43        **31,605**
  Conditions**                                                                                                             

                 Wet         1,641          2,775       33        103       184       33       3        12       12        **4,796**

                 Snow, Slush 113            11          26        307       4         2        0        1        2         **466**

                 Ice         237            37          72        143       20        0        2        9        3         **523**

                 Sand, Dirt, 37             2           0         0         0         0        0        2        1         **42**
                 Oil                                                                                                       

                 Other       57             0           0         1         4         0        0        4        0         **66**

                 Unknown     65             0           0         1         1         0        0        0        230       **297**

                 **Total**   **33,311**     **2,826**   **131**   **559**   **548**   **35**   **5**    **89**   **291**   **37,795**
  -------------- ----------- -------------- ----------- --------- --------- --------- -------- -------- -------- --------- ------------

**Table 6 -- 2001 Injury Crashes by Weather and Pavement Condition**

  -------------- ----------- --------------- ------------- ----------- ------------ ----------- --------- --------- ----------- ------------ ---------------
                             **Weather                                                                                                       
                             Conditions**                                                                                                    

                             Clear           Rain          Sleet       Snow         Fog         Rain, Fog Sleet,    Other       Unknown      **Total**
                                                                                                          Fog                                

  **Pavement     Dry         1,559,027       351           0           62           5,144       0         0         2,787       4,543        **1,571,914**
  Conditions**                                                                                                                               

                 Wet         102,221         206,221       955         7,332        3,327       832       263       943         1,547        **323,641**

                 Snow, Slush 5,829           361           1,034       17,915       79          0         0         374         765          **26,357**

                 Ice         17,813          3,078         2,500       14,717       351         79        0         1,264       2,352        **42,154**

                 Sand, Dirt, 2,326           99            0           0            0           0         0         0           95           **2,520**
                 Oil                                                                                                                         

                 Other       2,640           0             0           0            0           0         0         60          265          **2,965**

                 Unknown     14,733          0             0           111          0           0         0         0           9,474        **24,318**

                 **Total**   **1,704,589**   **210,110**   **4,489**   **40,137**   **8,901**   **911**   **263**   **5,428**   **19,041**   **1,993,869**
  -------------- ----------- --------------- ------------- ----------- ------------ ----------- --------- --------- ----------- ------------ ---------------

**Table 7 -- 2001 Property-Damage-Only Crashes by Weather and Pavement
Condition**

  -------------- ----------- --------------- ------------- ------------ ------------- ------------ ----------- -------- ----------- --------- ---------------
                             **Weather                                                                                                        
                             Conditions**                                                                                                     

                             Clear           Rain          Sleet        Snow          Fog          Rain, Fog   Sleet,   Other       Unknown   **Total**
                                                                                                               Fog                            

  **Pavement     Dry         3,260,534       274           0            80            13,479       0           0        5,052       0         **3,279,420**
  Conditions**                                                                                                                                

                 Wet         278,074         464,605       2,070        16,589        16,018       1,348       9        1,368       0         **780,081**

                 Snow, Slush 24,203          900           1,445        55,613        672          0           79       337         0         **83,249**

                 Ice         54,318          6,981         7,748        54,436        1,210        314         0        2,193       0         **127,199**

                 Sand, Dirt, 6,834           0             0            0             0            0           0        0           0         **6,834**
                 Oil                                                                                                                          

                 Other       5,528           0             0            81            0            0           0        0           0         **5,609**

                 Unknown     0               0             0            0             0            0           0        0           0         **0**

                 **Total**   **3,629,491**   **472,760**   **11,262**   **126,799**   **31,379**   **1,662**   **88**   **8,950**   **0**     **4,282,392**
  -------------- ----------- --------------- ------------- ------------ ------------- ------------ ----------- -------- ----------- --------- ---------------

**CONCLUSION**

In 2001, more than 22 percent of vehicle crashes were weather-related.
Over 16 percent of crash fatalities and more than 20 percent of crash
injuries in passenger vehicles occurred in adverse weather and/or slick
pavement. Most weather-related crashes occur when the pavement is wet
and during rainfall.

**REFERENCES**

1.  U.S. DOT, "Traffic Safety Facts 2001: A Compilation of Motor Vehicle
    Crash Data from the Fatality Analysis Reporting System (FARS) and
    the General Estimates System (GES)," National Highway Traffic Safety
    Administration (NHTSA), DOT HS 809 484, December 2002,
    <http://www-nrd.nhtsa.dot.gov/pdf/nrd-30/ncsa/tsfann/tsf2001.pdf>.

2.  U.S. DOT, "Fatality Analysis Reporting System (FARS)", National
    Highway Traffic Safety Administration (NHTSA),
    <http://www-fars.nhtsa.dot.gov/>.

3.  U.S. DOT, "General Estimates System (GES)", National Highway Traffic
    Safety Administration (NHTSA),
    <http://www-nrd.nhtsa.dot.gov/departments/nrd-30/ncsa/ges.html>.