Office of Transportation EPA420-S-06-2006 

and Air Quality December 2006 

Motor Coach Idling Field 

Observation Study for 

Washington, DC, Metro Area 
EPA420-S-06-004 

December 2006 

Motor Coach Idling Field Observation Study

for Washington, DC, Metro Area 

Transportation and Regional Programs Division

and 

SmartWay Transport Partnership Group

Office of Transportation and Air Quality 

U.S. Environmental Protection Agency 
Table of Contents 

OVERVIEW .......................................................................................................................... 1 

METHODOLOGY.................................................................................................................. 2 

RESULTS ............................................................................................................................. 3 

CONCLUSION .................................................................................................................... 11 

Appendix A: General Results .......................................................................................... 12 

Appendix B: Results by Shift .......................................................................................... 16 

Appendix D: Results by Individual Site .......................................................................... 23 

Appendix E: Data ............................................................................................................ 32 

Appendix F: Sample Observation Form.......................................................................... 35 

Appendix G Washington, DC Department of Environment Comments ......................... 36 

i 
ACKOWLEDGEMENT 

The Environmental Protection Agency would like to acknowledgement the efforts of 

Sarabeth G. Craig of the University of New Hampshire and Aaron R. Wright of the Ohio 

State University, as part of The Washington Center Internship Program, without whom 

this study would not have been possible. 

ii 
OVERVIEW 

Motor coaches idle their main propulsion engine for long periods, primarily to maintain a 

comfortable interior compartment for their passengers (heat or air conditioning). Another 

often cited reason for bus idling is to maintain air brake pressure. Due to the cavernous 

interior compartment of motor coaches, maintaining a comfortable interior temperature 

requires substantially more time than the typical long-haul truck cab or personal 

passenger vehicle. In fact, it can take hours to bring the interior of a standing bus from 

20 degrees Fahrenheit to 60 degrees Fahrenheit. Long-duration idling waste a 

considerable amount of fuel (up to a gallon per hour) and exposes the driver, passengers, 

and the general public to harmful diesel air emissions, such as particulate matter and 

other air toxics.1 

Unlike long haul trucks idling at truck stops which are largely hidden from public view, 

motor coach idling is highly visible. Motor coaches transport passengers to popular 

public destinations. Consequently, many state and local jurisdictions have received 

complaints about idling buses, and many of these states and local jurisdictions have 

promulgated laws that restrict vehicle idling. The city of Washington, DC is one 

jurisdiction that has passed an anti-idling law. In 1999, the DC Department of Health 

amended a municipal regulation (Title 20, §900.1) that applies to both gasoline and diesel 

engines. The DC idling law, which applies to buses with a seating capacity of twelve or 

more, restricts idling to three minutes. The law exempts private passenger vehicles, 

idling to power on-board equipment (e.g., cement mixers), and idling when the 

temperature is thirty-two degrees Fahrenheit or below (5 minutes only). Fines can be up 

to $5,000. See Appendix G for more information on DC’s anti-idling law. 

In an effort to better understand motor coach idling, the Environmental Protection 

Agency (EPA) conducted a field observation of motor coaches in and around the 

Washington, DC metro area. The purpose of this study was to observe and report idling 

behavior of motor coaches in various zones. The ultimate goal of this study is to begin a 

dialogue that will reduce idling emissions through education, communication, and 

strategies and technologies; and maintain the needs of motor coach buses, and their 

drivers and passengers. 

This study was conducted in the summer months of 2005, which generally have warmer 

temperatures and more tourists visiting the nation’s capital than other months. 

Consequently, the findings from this study may reflect increased idling behavior during 

the summer season as compared to other seasons. Because Washington, DC has enacted 

an idling restriction law, this law also may have effected idling times. It should be noted 

that this study was limited to observations in the Washington, DC metro area only. Other 

jurisdictions may experience different results. 

 The terms “motor coach” and “bus” are used interchangeably throughout this document. 

1

1
METHODOLOGY 

Ten public zones were initially selected as locations to regularly monitor motor coach 

idling behavior. These zones were selected based on preliminary observations made 

around the major tourist attractions in Washington, DC. While other tourist attractions 

exist, initial observations confirmed that motor coaches regularly visit these locations. 

The original locations are as follows: 

1. North National Mall – Madison Dr. NW 

2. South National Mall – Jefferson Dr. SW 

3. Lincoln/F.D.R. Memorials – Ohio Dr. SW 

4. National Cathedral 

5. Waterfront 

6. Arlington National Cemetery (in Virginia) 

7. Union Station 

8. US Capital/Supreme Court/Library of Congress 

9. Ford’s Theatre/Hard Rock Café/FBI Building 

10. National Zoo 

Observations occurred over a nine-week period, beginning on June 10, 2005 and ending 

on August 9, 2005. After a two-week trial observation period, zones 8, 9, and 10 above 

were removed. These three zones did not have sufficient numbers of buses to continue 

observations, and had ongoing construction activities that limited the amount of parking 

or had no parking at all for buses. Finally, the Lincoln/FDR Memorials site was 

determined to be too large for one zone observation, so the site was split into two 

different zones. The final zones for observation were as follows: 

1. North National Mall – Madison Dr. NW 

2. South National Mall – Jefferson Dr. SW 

3. Lincoln Memorial 

4. F.D.R. Memorial – Ohio Dr. SW 

5. National Cathedral 

6. Waterfront 

7. Arlington National Cemetery 

8. Union Station 

These remaining eight zones were each visited a total of four times (with the exception of 

the South National Mall and F.D.R Memorial zones, which were visited 3 times), 

resulting in 30 full days of observations. Using a rotating schedule, each zone was 

visited on different days of the work week. Observations occurred in two shifts per 

location: from 10am-1pm and from 1pm-4pm. Each morning shift was viewed as 

independent from each afternoon shift, and information from one shift was shared with 

the second shift to avoid overlapping. In the end, the results from both shifts where 

combined into the results for the day. 

2
RESULTS 

General Results 

Of the 1,173 observed buses, 618 buses (53%) were idling and 555 buses (47%) were not 

idling. As demonstrated in Figures 1 and 2, most of the idling trucks were in violation of 

the 3-minute Washington, DC idling law. The median idling time was 11 minutes and 

the average idling time was 16 minutes. 

Figure 1 Figure 2 

Idling Buses vs Non-Idling Buses Idling Times for 618 Buses 

555 

47% 

618 

53% 

197 

32% 

168 

27% 

144 

23% 

109 

18% 

Idled 3 minutes or less

Number of Non-Idling Buses

Number of Idling Buses 

Idled between 4 and 10 minutes 

Idled between 11 and 20 minutes 

Idled more than 20 minutes 

Results by Shift 

As would be expected during the summer months, more buses were observed idling 

during the afternoon hours than in the morning when the temperatures are higher. In 

addition, a larger proportion of these trucks were idling for over 3 minutes in the 

afternoon than in the morning. 

Morning Observations (10am – 1pm): 

Of 465 observed buses, 155 buses (33%) were idling and 310 buses (67%) were not 

idling. The maximum idling time was 38 minutes, and the median idling time was 17 

minutes. The average idling time was 19 minutes. Figure 3 provides a breakdown of the 

number of buses idling for various time intervals. 

Afternoon Observations (1pm – 4pm): 

Of 708 observed buses, 463 buses (65%) were idling and 245 buses (35%) were not 

idling. The maximum idling time was 1 hour 4 minutes, and the median idling time was 

17 minutes. The average idling time was also 17 minutes. Figure 4 provides a 

breakdown of the number of buses idling for various time intervals. 

3
Figure 3

10am - 1pm Idling

36 

46 23% 

30% 

31 42 

20% 27% 

Idled 3 minutes or less 

Idled between 4 and 10 minutes 

Idled between 11 and 20 minutes 

Idled more than 20 minutes 

Results by Daily Temperature 

Temperature – below 80°F 

98 

21% 

137 

30% 

Figure 4 

1pm-4pm Idling 

73 

16% 

155 

33% 

Idled 3 minutes or less 

Idled between 4 and 10 minutes 

Idled between 11 and 20 minutes 

Idled more than 20 minutes 

Of the 66 observed buses, 53 (80%) were idling and 13 buses (20%) were not idling. The 

maximum idling time was 29.5 minutes, and the median idling time was 5 minutes. The 

average idling time was 7 minutes. 

Of the 53 buses that were observed 

idling, the majority of them were 

idling for over 3 minutes, in violation 

of the Washington, DC law. Figure 5 

provides a breakdown of the number 

of trucks idling for various time 

intervals. 

Figure 5 

Idling Times at below 80°F 

2 

4% 

7 14 

13% 26% 

30 

57% 

Idled 3 minutes or less 

Idled between 4 and 10 minutes 

Idled between 11 and 20 minutes 

Idled more than 20 minutes 

4
Temperature – between 80°F and 90°F 

Of the 758 buses observed, 373 buses 

(49%) were idling and 385 buses (51%) 

were not idling. The maximum idling 

time was 1 hour 11 minutes, and the 

median idling time was 11 minutes. The 

average idling time was 16 minutes. 

Of the 373 buses that idled, only 61 buses 

(16%) idled for 3 minutes or less. The 

remaining 312 buses (84%) idled for over 

3 minutes and were in violation of the 

idling law for Washington, DC. 

Continuing with the idling times 

breakdown: 122 buses (30%) idled for 

somewhere between 4 and 10 minutes, 108 

buses (29%) idled for somewhere between 

11 and 20 minutes, and 82 buses (22%) 

idled for more than 20 minutes. (Figure 6) 

Temperature – above 90°F 

Of the 349 buses observed, 192 buses (55%) were 

idling and 157 buses (45%) were not idling. The 

maximum idling time was 1 hour 11 minutes, and 

the median idling time was 12 minutes. The overall 

average idling time was 18 minutes. 

Of the 192 buses that idled, only 34 buses (18%) 

idled for 3 minutes or less. The remaining 158 

buses (82%) idled for over 3 minutes and were in 

violation of the idling law Washington, DC. 

Continuing with the idling times breakdown: 45 

buses (23%) idled for somewhere between 4 and 10 

minutes, 53 buses (28%) idled between 11 and 20 

minutes, and 60 buses (31%) idled for more than 20 

minutes. (Figure 7) 

Figure 6 

Idling Times at between 80°F and 90°F 

61 82 16% 22% 

122 

108 33% 

29% 

Idled 3 minutes or less 

Idled between 4 and 10 minutes 

Idled between 11 and 20 minutes 

Idled more than 20 minutes

 Figure 7

Idling Times at above 90°F

34 

18% 

60 

31% 

45 

23% 

53 

28% 

Idled 3 minutes or less 

Idled between 4 and 10 minutes 

Idled between 11 and 20 minutes 

Idled more than 20 minutes 

5
Results by Individual Sites 

North National Mall – Madison Dr. NW 

The area observed was Madison Dr. NW between 14th Ave. NW and 7th Ave. NW. 

Overall, of the 1,173 total buses observed, 175 buses (15%) were observed at this zone, 

the 3rd highest out of the 8 sites. Of the 618 total idling buses observed, 109 idling buses 

(17%) were observed in this zone, which was the highest overall (tied with Arlington 

National Cemetery). 

For the site, of the 175 buses observed, 109 buses (62%) were observed idling and 66 

buses (38%) were not idling. The maximum idling time was 1 hour 6 minutes, and the 

median idling time was 13 minutes. The average idling time was 16. 

Overall, of the 109 buses that idled, only 34 buses (31%) idled for 3 minutes or less. The 

remaining 75 buses (69%) idled for over 3 minutes and were in violation of the 

Washington, DC idling law. Continuing with the idling times breakdown: 43 buses 

(40%) idled for somewhere between 4 and 10 minutes, 22 buses (20%) idled for 

somewhere between 11 and 20 minutes, and 10 buses (9%) idled for more than 20 

minutes. 

South National Mall – Jefferson Dr. SW 

The area observed was Jefferson Dr. SW between 7th Ave. SW and 3rd Ave. SW. 

Overall, of the 1,173 total buses observed, 196 buses (17%) were observed in this zone, 

the 2nd highest out of the 8 sites. Out of the 618 total idling buses observed, 94 idling 

buses (15%) were observed in this zone, which was 2nd highest out of 8. 

For the site, of the 196 buses observed, 94 buses (48%) were observed idling and 102 

buses (52%) were not idling. The maximum idling time was 2 hours 7 minutes, and the 

median idling time was 11 minutes. The overall average idling time was 19 minutes. 

Overall, of the 94 buses that idled, only 36 buses (36%) idled for 3 minutes or less. The 

remaining 58 buses (64%) idled for over 3 minutes and were in violation of the 

Washington, DC idling law. Continuing with the idling times breakdown: 25 buses 

(27%) idled for somewhere between 4 and 10 minutes, 22 buses (23%) idled for 

somewhere between 11 and 20 minutes, and 11 buses (12%) idled for more than 20 

minutes. 

Lincoln Memorial 

The area observed was Daniel C. French Dr. SW between Lincoln Memorial Circle SW 

and Independence Ave. SW. 

6
Overall, of the 1,173 total buses observed, 118 buses (10%) were observed in this zone, 

the 6th highest out of the 8 sites. Of the 618 total idling buses observed, 72 idling buses 

(12%) were observed at this zone, which was 4th highest out of 8. 

For the site, of the118 buses observed, 72 buses (61%) were observed idling and 46 buses 

(39%) were not idling. The maximum idling time was 37 minutes, and the median idling 

time was 8.5 minutes. The average idling time was 12 minutes. 

Overall, of the 72 buses that idled, only 21 buses (29%) idled for 3 minutes or less. The 

remaining 51 buses (71%) idled for over 3 minutes and were in violation of the 

Washington, DC idling law. Continuing with the idling times breakdown: 21 buses 

(29%) idled for somewhere between 4 and 10 minutes, 15 buses (21%) idled for 

somewhere between 11 and 20 minutes, and 15 buses (21%) idled for more than 20 

minutes. 

F.D.R. Memorial – Ohio Dr. SW 

The area observed was W. Basin Dr. SW between Independence Ave. SW and Ohio Dr. 

SW and Ohio Dr. SW between W. Basin Dr. SW and the bridge over the Tidal Basin. 

Overall, of the 1,173 total buses observed, 82 buses (7%) were observed in this zone, the 

7th highest out of the 8 sites. Of the 618 total idling buses observed, 30 idling buses (5%) 

were observed at this zone, which was lowest overall. 

For the site, of the 82 buses observed, 30 buses (37%) were observed idling and 52 buses 

(63%) were not idling. The maximum idling time was 50 minutes, and the median idling 

time was 12 minutes. The average idling time was 19 minutes. 

Overall, of the 30 buses that idled, only 5 buses (17%) idled for 3 minutes or less. The 

remaining 25 buses (83%) idled for over 3 minutes and were in violation of the 

Washington, DC idling law. Continuing with the idling times breakdown: 10 buses 

(33%) idled for somewhere between 4 and 10 minutes, 8 buses (27%) idled for between 

11 and 20 minutes, and 7 buses (23%) idled for more than 20 minutes. 

7
National Cathedral 

The area observed was the bus drop-off zone in front of the National Cathedral. 

Overall, of the 1,173 total buses observed, 72 buses (6%) were observed in this zone, the 

lowest overall. Out of the 618 total idling buses observed, 58 idling buses (9%) were 

observed at this zone, which was 7th highest out of the 8 sites. 

For the site, of the 72 buses observed, 58 buses (81%) were observed idling and 14 buses 

(19%) were not idling. The maximum idling time was 22 minutes, and the median idling 

time was 3.5 minutes. The overall average idling time was 7 minutes. 

Overall, of the 58 buses that idled, only 17 buses (29%) idled for 3 minutes or less. The 

remaining 41 buses (71%) idled for over 3 minutes and were in violation of the 

Washington, DC idling law. Continuing with the idling times breakdown: 31 buses 

(54%) idled for somewhere between 4 and 10 minutes, 7 buses (12%) idled for 

somewhere between 11 and 20 minutes, and 3 buses (5%) idled for more than 20 

minutes. 

Waterfront 

The area observed was Maine Ave. SW between M St SW and the Interstate 395 

overpass. 

Overall, of the 1,173 total buses observed, 229 buses (19%) were observed in this zone, 

the highest overall. Out of the 618 total idling buses observed, 66 idling buses (11%) 

were observed at this zone, which was 6th highest out of the 8 sites. 

For the site, of the 229 buses observed, 66 buses (29%) were observed idling and 163 

buses (71%) not idling. The maximum idling time was 1 hour 49 minutes, and the 

median idling time was 12 minutes. The average idling time was 22 minutes. 

Overall, of the 66 buses that idled, only 10 buses (15%) idled for 3 minutes or less. The 

remaining 56 buses (85%) idled for over 3 minutes and were in violation of the 

Washington, DC idling law. Continuing with the idling times breakdown: 19 buses 

(29%) idled for somewhere between 4 and 10 minutes, 19 buses (29%) idled for 

somewhere between 11 and 20 minutes, and 18 buses (27%) idled for more than 20 

minutes. 

8
Arlington National Cemetery 

The area observed was the bus parking lot at the Arlington National Cemetery in 

Virginia. 

Overall, of the 1,173 total buses observed, 162 buses (14%) were observed at this zone, 

the 4th highest out of the 8 sites. Out of the 618 total idling buses observed, 102 idling 

buses (11%) were observed at this zone, which was the highest out of 8 (tied with 

National Mall-Madison Dr.). 

For the site, out of 162 buses observed, 102 buses (63%) were observed idling and 60 

buses (37%) were not idling. The maximum idling time was 1 hour 32 minutes, and the 

median idling time was 13 minutes. The overall average idling time was 20 minutes. 

Virginia has an anti-idling law which allows buses to idle for up to 10 minutes during hot 

weather in order to maintain power to the air conditioning system. Of the 102 buses that 

idled, only 47 buses (46%) idled for 10 minutes or less. The remaining 55 buses (54%) 

idled for over 10 minutes and were in violation of Virginia law. Continuing with the 

idling times breakdown: 17 buses (17%) idled for somewhere between 11 and 20 

minutes and 38 buses (37%) idled for more than 20 minutes. 

Union Station 

The area observed was the parking garage behind Union Station. 

Overall, of the 1,173 total buses observed, 139 buses (12%) were observed in this zone, 

the 5th highest overall. Out of the 618 total idling buses observed, 87 idling buses (14%) 

were observed at this zone, which was 3rd highest out of the 8 sites. 

For the site, of the 139 buses observed, 87 buses (63%) were observed idling and 52 

buses (37%) were not idling. The maximum idling time was 1 hour, and the median 

idling time was 13 minutes. The average idling time was 18.9 minutes. 

Overall, of the 87 buses that idled, only 14 buses (16%) idled for 3 minutes or less. The 

remaining 73 buses (84%) idled for over 3 minutes and were in violation of the 

Washington, DC idling law. Continuing with the idling times breakdown: 20 buses 

(23%) idled for somewhere between 4 and 10 minutes, 34 buses (39%) idled for 

somewhere between 11 and 20 minutes, and 19 buses (22%) idled for more than 20 

minutes. 

Summary of Results for All Sites 

For all sites, a total of 1,173 parked buses were observed. Figure 8 demonstrates the 

number of buses (and the proportion of the total) that were parked at each site. Of these 

1,173 buses, 618 were observed idling. Figure 9 shows the proportion of these buses that 

were idling at each site. The largest number of buses observed idling was at the two 

9
combined National Mall locations. Figure 10 demonstrates the average idling times for 

each site. 

 Figure 8 Figure 9 

Number of Parked Buses by Site Number of Idling Buses by Site 

139 175 87 12% 15% 109 

14% 17% 

162 

14% 

196 102 

17% 17% 94 

15% 

229

19% 118 66

10% 11% 72 

72 82 

7% 58 30 12% 

6% 9% 5% 

National Mall A - Madison Ave. 

National Mall B - Jefferson Ave. 

Lincoln Memorial 

Ohio Drive - F.D.R. Memorial 

National Cathedral 

Waterfront 

Arlington National Cemetery 

Union Station 

National Mall A - Madison Ave. 

National Mall B - Jefferson Ave. 

Lincoln Memorial 

Ohio Drive - F.D.R. Memorial 

National Cathedral 

Waterfront 

Arlington National Cemetery 

Union Station Minutes

Figure 10

Average Idling Times by Site 25 

22 

19 20 20 19 19

15 

15 

10 

5 

0 

11 

7 

National Mall National Mall Lincoln Ohio Drive - National Waterfront Arlington Union Station 

A - Madison B - Jefferson Memorial F.D.R. Cathedral National 

Ave. Ave. Memorial Cemetery 

10
CONCLUSION 

This field observation found that the majority of motor coaches in Washington, DC idle 

their engines. Of this majority, over 80% idled beyond Washington, DC’s idling law 

limit. The average idling time ranged from 15-22 minutes with several instances of 

idling greater than one hour. 

Motor coaches were found to idle throughout the Washington, DC metropolitan area. 

This study focused on observing buses at eight popular tourist sites. However, motor 

coaches have been observed to park and idle at almost any available parking spaces in the 

city. 

A companion document to this field observation will discuss potential policy, technical, 

and strategic solutions to motor coach idling. 

11
Appendix A 

General Results 

Median and Average Idling Times....................................... 15 Breakdown of Number of Parked Buses by Site ....................... 16 Breakdown of Number of Idling Buses by Site ...........................17 

12 
Median and Average Idling Times 

Median Idling Time Average Idling Time 

10.66666667 

16.39663191 

0 2 4 6 8 

10 12 14 16 18 

minutes 

13
Breakdown of Number of Parked Buses by Site 

139 175

12% 

196 

17% 

15% 

162 

14% 

229 

118 19% 

10% 

82 72 7% 6% 

NaNaLinOhNaWaArlUn

14
Breakdown of Number of Idling Buses by Site 

87 109 14% 17% 

102 

17% 

94 

15% 

58 

9% 

30 

5% 

66

11% 72 

12% 

National Mall A - MadisoNational Mall B - JeffersoLincoln Memorial Ohio Drive - F.D.R. MemNational Cathedral Waterfront Arlington National CemetUnion Station 

15
Appendix B 

Results by Shifts 

Idling Buses vs Non-Idling Buses (10 am-1pm Observations).................... 19 Breakdown of Idling Times (10 am-1pm Observations)........................ 19 Idling Buses vs Non-Idling Buses (1pm-4pm Observations).................... 19 Breakdown of Idling Times (1pm-4pm Observations)............................19 Median and Average Idling Times (10 am-1pm Observations)............... 20 Median and Average Idling Times (1pm-4pm Observations).................. 20 

16
Idling Buses vs Non-Idling Buses 

(10am - 1pm Observations) 

Breakdown of Idling Times 

(10am - 1pm Observations) 

36 

23% 

46

155 30%

33%

Number of Idling Buses Number of Non-Idling Buses 

310

67%

Idling Buses vs Non-Idling Buses 

(1pm - 4pm Observations) 

245 

35% 

42 

27% 

31 

20% 

Breakdown of Idling Times 

(1pm - 4pm Observations) 

73

98 16%

21% 

Number of Idling Buses Number of Non-Idling Buses 

463 

65% 

137 

155 

33% 

30% 

17
Median and Average Idling Times 

(10am - 1pm Observations) 

17 

18.54155556 

16 

16.5 

17 

17.5 

18 

18.5 

19 

minutes 

Median Idling Time Average Idling Time Median and Average Idling Times 

(1pm - 4pm Observations) 

18161412

minutes 10

86420 

10.67857143 

Median Idling Time A

18
Appendix C 

Results by Daily Temperature 

Idling Buses vs. Non Idling Buses Below 80E F............... 22 Breakdown of Idling Times Below 80E F........................ 22 Median and Average Idling Times Below 80E F................ 22 Idling Buses vs. Non Idling Buses Between 80-90E F........ 23 Breakdown of Idling Times Between 80-90E F................ 23 Median and Average Idling Times Between 80-90E F........ 23 Idling Buses vs. Non Idling Buses Above 90E F................ 24 Breakdown of Idling Times Between Above 90E F............ 24 Median and Average Idling Times Above 90E F............... 24 

19
Idling Buses vs Non-Idling Buses 

(Temperatures below 80°F) 

Breakdown of Idling Time

(Temperatures below 80°F

2 

4% 

13 7 

13% 20% 14

26%

Number of Idling Buses Number of Non-Idling Buses 

53 30 

80% 57% 

Median and Average Idling Times 

(Temperatures below 80°F) 

Median Idling Time Average Idling Time 

4.75 

7.386178862 

0 1 2 3 4 5 6 7 8 

minutes 

20
Idling Buses vs Non-Idling Buses Breakdown of Idling Times 

(Temperatures between 80°F and 90°F) (Temperatures between 80°F and 90°F

61 

16% 82 

22% 

373 

Number of Idling Buses 385 49% Number of Non-Idling Buses 51% 

122 

33% 

108 

29% 

Median and Average Idling Times 

(Temperatures between 80°F and 90°F) 

Median Idling Time Average Idling Time 

10.35294118 

16.30044454 

0 2 4 6 8 

10 12 14 16 18 

minutes 

21
Idling Buses vs Non-Idling Buses Breakdown of Idling Times 

(Temperatures above 90°F) (Temperatures above 90°F) 

34 

18% 

60 

31% 

157 

45% 

Number of Idling Buses Number of Non-Idling Buses 

55% 

192 

2

Median and Average Idling Times 

(Temperatures above 90°F) 

53 

28% 

Median Idling Time Average Idling Time 

12.22727273 

18.1835493 

0 2 4 6 8 

10 12 14 16 18 20 

minutes 

22
Appendix D 

Results by Site 

North National Mall – Madison Dr. NW........................ 26 South National Mall – Jefferson Dr. SW........................ 27 Lincoln Memorial................................................... 28 F.D.R. Memorial – Ohio Dr. SW.................................29 National Cathedral.................................................. 30 Waterfront............................................................31 Arlington National Cemetery......................................32 Union Station........................................................ 33 

23
Idling Buses vs Non-Idling Buses Breakdown of Id

(North National Mall - Madison Dr. NW) (North National Mall - M

10 

9% 

22 

20% 

66 

38% 

Number of Idling Buses Number of Non-Idling Buses 

109

62%

43 

40% 

24
Idling Buses vs Non-Idling Buses Breakdown of Idlin

(South National Mall - Jefferson Dr. SW) (South National Mall - Jeff

11 

12% 

22 

23% 

94

48% Number of Idling Buses 

102 Number of Non-Idling Buses 

52% 

25 

27% 

25
Idling Buses vs Non-Idling Buses Breakdown of Idli

(Lincoln Memorial) (Lincoln Mem

15 

21% 

2

29

46 

39% 

Number of Idling Buses Number of Non-Idling Buses 

72 15 

61% 21% 

21 

29% 

26
Idling Buses vs Non-Idling Buses 

(F.D.R. Memorial - Ohio Dr. SW) Breakdown of Idling 

(F.D.R. Memorial - Ohio 

5 

7 17% 

23% 

30

37%

Number of Idling Buses Number of Non-Idling Buses 

52 

63% 

10 

33% 

8 

27% 

27
Idling Buses vs Non-Idling Buses 

(National Cathedral) 

Breakdown of Id

(National Cat

3 

5% 

7

14 12%

19% 

2

Number of Idling Buses Number of Non-Idling Buses 

58

81%

31 

54% 

28
Idling Buses vs Non-Idling Buses Breakdown of Idlin

(Waterfront) (Waterfront) 

10 

15% 

18

66 27%

29%

Number 

of Idling Buses 

Number 

of Non-Idling Buses 

163 

71% 

19 

29% 

29
Idling Buses vs Non-Idling Buses 

(Arlington National Cemetery) Breakdown of Idli

(Arlington National 

21 

21% 

Number of Idling Buses Number of Non-Idling Buses 

60 

37% 38 

37% 

102

63%

17 

17% 

30
Idling Buses vs Non-Idling Buses Breakdown of Idlin

(Union Station) (Union Statio

14 

19 16% 

22% 

52 

37% 

Number of Idling Buses Number of Non-Idling Buses 

87 

63% 

34 

39% 

31
Appendix E 

Data 

32 
Number of Buses Idling at Each Site, by Temperature and Shift 

Sites Temperature Not Idling Total Idling Total 

AM PM AM PM 

North National Mall - Less than 80° 12 0 12 0 0 0 

Madison Dr. NW 80°-90° 8 27 35 8 71 79 

More than 90° 3 16 19 3 27 30 

Total=175 23 43 66 11 98 109 

South National Mall - Less than 80° 0 18 31 0 32 32 

Jefferson Dr. SW 80°-90° 41 43 84 13 49 62 

More than 90° 0 0 0 0 0 0 

Total=196 41 61 102 13 81 94 

Lincoln Memorial Less than 80° 0 1 1 0 19 19 

80°-90° 19 4 23 10 5 15 

More than 90° 20 2 22 20 18 38 

Total=118 39 7 46 30 42 72 

F.D.R. Memorial - Ohio Dr. Less than 80° 0 0 0 0 0 0 

SW 80°-90° 23 29 52 10 20 30 

More than 90° 0 0 0 0 0 0 

Total=82 23 29 52 10 20 30 

National Cathedral Less than 80° 13 0 13 15 0 15 

80°-90° 0 0 0 0 38 38 

More than 90° 0 1 1 0 5 5 

Total=72 13 1 14 15 43 58 

Waterfront Less than 80° 46 0 46 5 0 5 

80°-90° 16 39 55 2 26 28 

More than 90° 19 43 62 6 27 33 

Total=229 81 82 163 13 53 66 

Arlington National Less than 80° 36 0 36 9 0 9 

Cemetery 80°-90° 0 9 9 0 35 35 

More than 90° 14 1 15 32 26 58 

Total=162 50 10 60 41 61 102 

Union Station Less than 80° 0 0 0 0 0 0 

80°-90° 40 6 46 22 34 56 

More than 90° 0 6 6 0 31 31 

Total=139 40 12 52 22 65 87 

ALL SITES Less than 80° 107 19 139 29 51 80 

80°-90° 147 157 304 65 278 343 

More than 90° 56 69 125 61 134 195

Total=1,173 310 245 568 155 463 618 

33 
Number of Buses Idling at Each Site, by Temperature, Shift, and Length of Time 

Sites Temperature 3 minutes or 4 to 10 11 to 20 More than Total 

less minutes minutes 20 minutes 

AM PM AM PM AM PM AM PM 

North National Mall - Less than 80° 0 0 0 0 0 0 0 0 0 

Madison Dr. NW 80°-90° 6 1 1 22 1 31 0 17 79 

More than 90° 0 3 1 10 1 10 1 4 30 

Total=175 6 4 2 32 2 41 1 21 109 

South National Mall - Less than 80° 0 2 0 18 0 6 6 0 32 

Jefferson Dr. SW 80°-90° 4 5 5 13 17 2 14 2 62 

More than 90° 0 0 0 0 0 0 0 0 0 

Total=196 4 7 5 31 17 8 20 2 94 

Lincoln Memorial Less than 80° 0 6 0 7 0 5 0 1 19 

80°-90° 2 2 2 2 1 0 5 1 15 

More than 90° 6 5 4 6 4 5 6 2 38 

Total=118 8 13 6 15 5 10 11 4 72 

F.D.R. Memorial - Ohio Dr. Less than 80° 0 0 0 0 0 0 0 0 0 

SW 80°-90° 3 2 4 6 7 1 5 2 30 

More than 90° 0 0 0 0 0 0 0 0 0 

Total=82 3 2 4 6 7 1 5 2 30 

National Cathedral Less than 80° 3 0 10 0 1 0 1 0 15 

80°-90° 0 11 0 20 0 6 0 1 38 

More than 90° 0 3 0 1 0 0 0 1 5 

Total=72 3 14 10 21 1 6 1 2 58 

Waterfront Less than 80° 1 0 3 0 1 0 0 0 5 

80°-90° 0 5 0 10 2 4 0 7 28 

More than 90° 0 4 1 5 5 7 0 11 33 

Total=229 1 9 4 15 8 11 0 18 66 

Arlington National Less than 80° 0 0 1 0 4 0 4 0 9 

Cemetery 80°-90° 0 11 0 15 0 3 0 6 35 

More than 90° 7 3 6 4 3 7 16 12 58 

Total=162 7 14 7 19 7 10 20 18 102 

Union Station Less than 80° 0 0 0 0 0 0 0 0 0 

80°-90° 4 4 4 5 5 18 9 7 56 

More than 90° 0 6 0 11 0 11 0 3 31 

Total=139 4 10 4 16 5 29 9 10 87 

ALL SITES Less than 80° 4 8 14 25 6 11 11 1 80 

80°-90° 19 41 16 93 33 65 33 43 343 

More than 90° 13 24 12 37 13 40 23 33 195

Total=1,173 36 73 42 155 52 116 67 77 618 

34
Appendix F 

Sample Observation Form 

TODAY’S DATE: _____________________ TODAY’S TEMP. (F): _____________________ LOCATION: 

_____________________ 

OBSERVER (print): _____________________ OBSERVER (signature): _____________________ 

NO. TOUR BUS 

COMPANY NAME 

LICENSE PLATE # IDLING 

START TIME (am/pm) 

IDLING STOP TIME (am/pm) 

TOTAL IDLING TIME (MIN/HR) 

COM

Total Buses Parked = xx Total Buses Idling = xx Min Idling Time = xx minutes Max Idling Time = xx minutes Median Idling Time = xx minutes Mean Idling Time = xx minutes xx seconds 

35 
Appendix G 

Comments from the District of Columbia Air Quality Division 

Although the District of Columbia Air Quality Division has focused compliance 

initiatives on engine idling in the past five years, the United States Environmental 

Protection Agency (EPA) Motor Coach Study conducted in the summer of 2005 indicates 

that more work still needs to be done. 

The District of Columbia engine idling regulation was originally enacted in 1972. 

DC Rules & Regulations, Reg. 72-18. Later, the air quality regulations were reorganized 

and the idling regulation was adopted into Section 3 of the District’s Air Pollution 

Control Act of 1984 (D.C. Law 5-165, effective March 15, 1985; 20 DCMR 900.1, as 

amended). In an effort to curb motor vehicle emissions the District has amended the 

engine idling regulation several times since its original inception. Recent amendments 

have targeted limiting the number of exceptions to the three (3) minute time period 

allowed for idling, and increasing the penalty amount for violations. These measures 

have been necessary to reduce the amount of emissions during warm weather months 

when ozone reaches unsafe levels. As a result of these amendments, the District’s current 

engine idling regulation provides that: 

The engine of a gasoline or diesel powered motor vehicle, the engine of a 

public vehicle for hire, including buses with a seating capacity of twelve 

(12) or more persons, on public or private space shall not idle for more 

than three (3) minutes while the motor vehicle is parked, stopped, or 

standing, including for the purpose of operating air conditioning 

equipment in those vehicles, except as follows: 

(a) To operate private passenger vehicles; 

(b) To operate power takeoff equipment including, 

dumping, cement mixers, refrigeration systems, content 

delivery, winches, or shredders; or 

(c) To idle the engine for five (5) minutes to operate 

heating equipment when the ambient air temperature is 

thirty-two degrees Fahrenheit (32oF) or below. 

20 DCMR 900.1. The District of Columbia Department of Motor Vehicles (DMV) has a 

synonymous regulation codified in 18 DCMR 2418.3, which is enforced by other District 

and federal government agencies. 

Although the District has taken many measures to improve the air quality, the DC 

metropolitan area continues to fall below air quality standards established in the federal 

Clean Air Act, 42 U.S.C. §7401 et seq. Accordingly, EPA has identified the DC 

metropolitan area as a non-attainment area for ozone and particulate matter (PM) ambient 

air quality standards. As the District has very few industrial activities, the largest and 

most significant sources of the District’s air pollution problem are motor vehicles. 

36 
Vehicle exhaust emits nitrogen oxides (NOx), carbon monoxide (CO), 

hydrocarbons (HC), including volatile organic compounds (VOCs), and particulate 

matter (PM) into the atmosphere. In the presence of heat and sunlight, these pollutants 

create ozone. Ozone and some of the other pollutants mentioned above, especially PM, 

are the cause of many respiratory illnesses. Vehicles are most inefficient while idling 

because the fuel is not completely combusted and pollutants are released in higher level 

than when the vehicle is in operation. Therefore, excessive idling leads not only to many 

respiratory illnesses, but also the exhaust fouls the air with various pollutants that erode 

buildings and monuments. In short, vehicle exhaust causes damage to personal and real 

property. 

After observing an increase of violations in 2002 the District started an aggressive 

campaign to eradicate engine idling problems. The Air Quality Division stepped up 

enforcement and designed flyers to educate drivers about the engine idling regulation. 

Air quality inspectors hand out the flyers in high volume engine idling areas (markets, 

warehouses, and certain areas where tour buses park while waiting out the day), and the 

division sends the flyers to busing and trucking companies for postings in newsletters. In 

addition, the air quality attorney often settles cases for a lower penalty if the violator 

takes action to inform other drivers about the District’s engine idling regulation (i.e. 

notices in newsletters, notices attached to paychecks, letters to each driver in smaller 

companies, etc.). Due to these compliance and enforcement efforts, engine idling has 

been reduced in the District.2 

A disconcerting part of the EPA Motor Coach Study is that many of the violations 

occurred in areas not patrolled by the Air Quality Division. The federal Park Police and 

Capitol Police have primary jurisdiction over zones 3, 4, 5, and 7, and a significant 

portion of zones 1 and 2. Therefore, the District’s Air Quality Division must make better 

efforts to coordinate compliance initiatives with other District and federal agencies. The 

Air Quality Division plans to establish an engine idling task force with representatives 

from other agencies that have authority to enforce engine idling regulations including: the 

Department of Public Work’s Parking Enforcement Division; the Department of Motor 

Vehicles; the Metropolitan Police Department’s Motor Carrier Division; and federal 

agencies, such as the Park Police and Capitol Police. 

The District needs cooperation from the busing industry as well. Tour buses that 

idle for cabin temperature is particularly important for the transportation of senior 

citizens who are susceptible to health problems. The District understands that a 

comfortable cabin temperature is important for senior citizen health, but so is the impact 

2 Notices of Infraction (tickets) issued for violations of the District's engine idling regulations: 

2000: AQD 99 DMV 32 Total = 131 

2001: AQD 126 DMV 15 Total = 141 

2002: AQD 187 DMV 10 Total = 197 

2003: AQD 44 DMV 20 Total = 64 

2004: AQD 48 DMV 41 Total = 89 

37 
of inhalation from bus exhaust. The District cannot allow buses to idle for excessive 

periods of time simply to keep air conditioners running because that would frustrate the 

purpose of the idling law. Seniors who require ambulatory assistance and the wheelchair 

lift can take up to five minutes to safely load onto a bus. The District reasonably enforces 

the engine idling regulation and does not issue citations when passengers are loading or 

unloading. 

 Responsibility for controlling excessive idling must be shared with the 

government and the regulated industry. Engine idling can be greatly reduced through 

current technologies, such as mobile idle reduction technologies, which provide auxiliary 

power to replace or supplement diesel engine idling while the vehicle is stopped. These 

units reduce idling, reduce fuel consumption, extend engine maintenance intervals, 

reduce wear on engines and help vehicles comply with anti-idling laws. These 

technologies can be safely installed into one luggage space of tour buses, and would 

greatly reduce excessive idling. In addition, other technologies are available, such as 

stationary electrified parking spaces, wherein drivers hook up to a metered machine that 

provides heating, air-conditioning, phone service and electricity. Busing and trucking 

companies can install mobile idle reduction technologies on their own vehicles. 

However, a stationary electrified parking system would require a coordinated industry 

effort due to the necessity to have a convenient area where large vehicles could park and 

hook up to the machines. 

The District is committed to reducing engine idling and is willing to work with 

the regulated industry and other governmental entities to accomplish this goal. The 

planned task force will help coordinate enforcement initiatives, but education and 

assistance with preventative technologies will provide the most benefit for the citizens 

and visitors to the District of Columbia. 

Kimberly Katzenbarger Neil Williams 

Counsel to the Air Quality Division Air Quality Division Environmental Engineer 

The District of Columbia Air Quality Division 

51 N Street, NE 

Washington, DC 20002 

202-535-2257 

38