EPA-AA-ECTD 74-2
Amendments to the Report on
Development of a Highway Driving Cycle
for Fuel Economy Measurements
by
C. Don Paulsell
April, 1974
' Environmental Protection Agency
Office of Air Programs
Office of Mobile Source Air Pollution Control
Emission Control Technology Division
Procedures Development Branch
Ann Arbor, Michigan
-------
Introduction:
>i • I •• ' * * ' ~
This report addresses several changes which have been made to
the highway driving cycle described in the report entitled, "Develop-
ment of a Highway Driving Cycle for Fuel Economy Measurements," dated
March, 1974. . - .
Purpose: •
The purpose of this report is to explain the reasons for modifying
the driving cycle and to summarize the characteristics of the updated
tabulation of the cycle.
Objective:
The objective of this report is to produce an amended speed versus
time tabulation of the highway driving cycle that is compatible with
all chassis dynamometers. .
- • :
Background:
The initial tabulation of the highway driving cycle was derived
in a three step process. The speeds were read from the actual trace
at .1 inch intervals, each interval representing 1.5 seconds. This
file was recomputed by a linear interpolation to yield a file with
speeds for each .5 second interval. By deleting ever/other point
from this .5 second file, a tabulation of speed versus time was
constructed at 1.0 second intervals.
s-
The characteristics of the various segments of the cycle were com-
puted from the "1.5" second file and were published as Table 3 in the
March, 197.4 report on cycle development.
Several organizations that have used the highway driving cycle
0.0 second tabulation) reported that the initial acceleration and
final deceleration rates were high enough to cause belt slippage on
dynamometers with belt-driven inertia weights. Calculations show
that the rates were about 4.9 mph/sec.
. The MSAPC laboratory has had no problems driving the cycle on the
direct-drive dynamometers. However, our experience with the development
of the LA-4 on belt-driven dynamometers supports the problem cited
above. The accelerations and decelerations on the LA-4 were normalized
to 3.3 mph/sec or less to avoid the slippage and wear problems.
This precedent has been applied to the highway driving cycle to
permit the use of this cycle on all existing equipment without causing
abnormal slippage'and wear.
-------
-2-
It was also reported that a summation of the (1-0 second) speed
versus time list did not agree exactly with the values shown in
Table 3. 'Although the differences were very small, this report will
summarize the characteristics for the updated speed-time tabulation.
Discussion of Amendments:
It was agreed among the engineers involved in the cycle development
that changes should be made only to the segments that were above the 3.3
rnph/sec limit rather than a simple linearization to 0 mph at each end of
the trace. Table A shows the tabulations of the two versions to illus-
trate which speeds were changed. Two seconds were added to the accelera
tion and a one second shift was made on the deceleration profile.
After these changes were made, a summation of the entire file
was computed for each segment and for the total cycle. This exercise
revealed the reason for the disparity between Table 3 and the summary
of the tabulated speeds. The values in Table 3 were computed from
the (1.5 second) file of speed versus time. In that file, two segments,
C and B ended on half seconds; therefore, these points were not shown ir
the .(1.0 second) tabulation.
This difference and the fact that the composite of Table 3 is
simply a summation of the four segments produces a small variation in
the final numbers.
Because the official version of the highway driving cycle will be
the one second tabulation of speed versus time, the appropriate summary
of characteristics should be based on this tabulation. This summary '
has been made.. The values have been shown in parentheses with the
previous values of Table 3 for comparison. Note that the average speed
is now based on total sample time rather than total driving time. This
value has no impact on the calculation of fuel economy.
The value of major impact on the calculation of fuel economy is
the total distance traveled. The new value of 10.242 miles differs
by + .16% from the previous value of 10.225. This updated value re-
flects the increase in time and the changes in speeds made to normalize
the acceleration and deceleration rates.
Conclusions and Recommendations:
The changes which have been made to the highway driving cycle
should permit its use without problems. The updated tabulation dated
(Monday April'22,'1974) is recommended for adoption as the official
driving cycle for highway fuel economy measurements.
-------
-3-
The magnitude of the changes which have been incorporated into
the updated version are not significant enough to invalidate any
tests which have been performed using the previous version. It is
recommended that previous measurements be accepted as valid and equi-
valent indications of highway fuel economy.
-------
TABLE A
.**** EPA HIGHWAY FUEL ECONOMY DRIVING CYCLE
*** SPEED (MPH) VS TIME (SEC) **»
ORIGINAL
CYCLE
MARCH 1974
SEC
0
1
2
3
4
5
6
7
8
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
MPH
SAMPLE ON
0.0
0.0
4.7
9.6
14.5
17.4
19.8
21.8
42.5
40.2
36.7
32.0
28.0
24.5
21.5
19.5
17.4
' 15.1
12.4
9.7
7.0
5.0
3.3
2.0
0.7
0.0
0.0
AMENDED
CYCLE
MON APR 22/74
SEC
MPH
0 SAMPLE ON
1
2
3
4
5
6
7
8
9
10
0.0
0.0
2.0
4.9
8.1
11.3
14.5
17.3
19.6
21.8
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
42.5
39.2
35.9
32.6
29.3
26.8
24.5
21.5
19.5
17.4
15.1
12.4
9.7
7.0
5.0
3.3
2.0
0.7
0.0
0.0
INITIAL
ACCELERATION
FINAL
DECELERATION
NEW POINT
762 SAMPLE OFF
765 SAMPLE OFF
MON APR 22/74
-------
TABLE 3
Characteristics of Composite Highway Driving Cycle*
Segment
Lenght
(IN)
9.5
11.5
17.0
12.5
( 0.13)
(9.60)
(11.53)
(17.00)
(12.60)
( 0.13)
50.5. (51.0 )
Inches
Segment
(Idle)
D
C
A
B
(Idle)
Overall
Total
Average
Speed
(MPH)
41.157
43.841
56.096
48.421
( 0.0 )
(40.736)
(43.835
(56.110)
(48.230)
( 0.0 )
48.595 (48.200)
MPH
1
2
3
2
•' 10
Distance
Traveled
(Miles)
( 0
.629 ( 1
<101 2
.973 ( 3
.522 ( 2
( o
.225 (10
Miles
• 0 ).'
.629)
.107)
.974)
.532)
.0 )
.242)
Elapsed
Time
(MIN) (SEC)
2.375
2.875
4.250
3.125
12.625
Minutes
2
144
173
255
189
2
765
Seconds
, % Total
Miles
15.93
20.55
38.85
24.67
100,0%
( o.o )
( 15.91)
(20.57)
( 38.80)
( 24.72)
( 0.0 )
(100.02)
(12.750)
NOTE: Previous overall average speed did not Include 4 second idle period,
*Values applicable to the amended version (Mon. April 22, 1974) are shown in parentheses.
-------
***** EPA HIGHWAY FUEL ECONOMY DRIVING CYCLE *****
*** SPEED (MPH) VS TIME (SEC) **+
MON APR 22/74
sec
0
i
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
1ft
19
20
21
22
£3
24
25
•t*6
27
2«
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
•48
49
MPH
SAMPLE
0.0
n.o
2.0
4.9
fi.-l
11.3
14.5
17.3
.' 19.6
21.8
24.0
?S.8
27.1
2*).0
29.0
30.0
30.7
31.5
32.2
3^.9
33.5
.34.1
34.6
34.9
3b.l
35.7
3b.9
35.8
35.3
34.9
34.5
34.6
34.8
35.1
35.7
36.1
3^.2
36.5
36.7
36.9
37.0
. 37.0
37.0
37.0
37.0
37.0
' 37.1
37.3
37.8
SEC
/
ON ' 50
bl
52
53
54
55
b6
57
58
S9
60
61
*2
63
64
65
66
67
68
69
70
71
72
73
74
. . 75
76
77
78
79
ao
HI'
82
83
84
fi5
86
87
flfl
*9
90
91
92
93
94
95
96
97
98
99
MPH
38.6
39.3
40.0
40.7
41.4
42.2
42.9
43. b
44. U
44.3
44.5
44.8
44.9
45.0
45.1
45.4
<;'5.7
46.0
46.3
46.5
46.8
46.9
47.0
47.1
47.2
47.3
47.2
47.1
47.0
46.9
46.9
46^9
47.0
47.1
47.1
47.2
4 V.I
47.0
46.9
46. b
4t>.3
46.2
46.3
46.5
46.9
47.1
47.4
47.7
4b.O
48.2
SEC
100
101
102
103
104
105
106
107
lOd
109
110
111
112
113
114
15
16
17
1H
19
20
121
122
123
' 124
125
126
127
128
129
130 '
131
132
133
134
135
136
137 '
133
139
140
141
. 142
143
144
145
146
147
14H
149
MPH
48.5
44.8
49.1
49.2
49.1
4*. 1
49.0
49.0
49.1
49.2
49.3
49.4
49. S
49.5
49.5
49.4
49.1
4f .9
40.6
48. 4
4M.1
47.7
47.4
47.3
47.5
47.8
47.9
48.0
47.9
47.9
47.9
4M.O
4B.O
44.0
47.9
47.3
46.0
43.3
41.2
39.5
39.2
39.0
39.0
39.1
39.5 '
40.1
41.0
42.0
43.1
43.7
SEC
150
151
152
153
154
155
156
157
15fl
159
160
161
16?
163
164
165
166
167
16A
169
170
171
172
173
174
175
176
177
178
179
180
181
1B2
Ifl3
184
1R5
186
187
IH(\
189
190
191
192
193
194
195
196
197
198
199
MPH
44.1
44.3
44.4
44.6
44.7
44.9
45.2
' 45.7
45.9
46.3
46.8
46.9
47.0
47.1
47,6
47.9
48.0
48.0
47.9
4V. 8
47.3
46.7
46.2
45.9
45.7
4b. 5
4b.4
4b.3
45.0
44.0
43.1
42.2
41.5
41.5
42.1
42.9
43.5
43.9
43.6
43.3
43.0
4J.1
43.4
43.9
44.3
44,6
44.9
44.8
44.4
43.9
SEC
200
201
202
203
• 204
. 20b
206
207
208
209
210
211
212
213
214';
215
216
21 7
210
219
220
221
222
223
224
22b
226
'ddl
228
229
230
231
232
233
234
23b
236
237
238
239
240
241
242
243
244
245
246
247
248
249
MPH
43.4
43i2
43.2
43.1
43.0
43.0
43.1
43.4
43.9
• 44.0
43. b
42.6
41.5
40.7
40.0
40.0
40.3
41.0
42.0
42.7
43.1
43.2
43.4
43.9
44.3
44.7
45.1
45.4
4b.B
46.5
46.9
47.2
47.4
47.3
47.3
47.2
47.2
47.2
47.1
47.0
47.0
46.9
4b,8
46.9
47.0
47. t
47. S
47.9
48.0
48.0
SEC
250
2bl
252
253
254
. 255
256
257
2b8
259
260
261
. 262
263
264
265
266
267
268
269
270
271
272
273
274
275
276 ..
277
278
279
280 •
281
282
283
2U4
285
286
287
288
289
290
291
292
293
294
295
296
297
298 '
299
MPH
48.0
48.0
48.0
48.1
48.2
.48.2
48.1
48.6
48.9
49.1
49.1
49.1
49.1
49.1
49.0
48.9
48.2
47.7
47.5
47.2
46.7
46.2
46.0
45.8
45.6
45.4
45.2
45.0.
44.7
44.5
44.2
43.5
42.8
42.0
40.1
3FU6
37.5
35.8
•34.7
34.0
33.3
32.5
31.7
30.6
29.6
28.8
28.4
28.6
29.5
31.4
SEC
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
. 330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
MPH
33.4
35.6
37.5
39.1
40.2
41.1
41.8
42.4
42.8
43.3
43.8
44.3
44.7
45.0
45.2
45.4
45.5
45.8
46.0
46.1
46.5
46.8
47.1
47.7
48.3
49.0
49.7
50.3
51.0
51.7
S2.4
53.1
53.8
54.5
55.2
55.8
56.4
56.9
57.0
57.1
57.3 .
57.6
57.8
58.0
58.1
58.4
53.7
58.8
58.9
b9.0
SEC
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
.373
374
375
376
377
378
379
380
381
382
383
384
385
3B6
387
388
389
390
391
392
393
394
395
396
39?
398
399
MPH
59.0
58.9
58.8
58.6
b8.4
58.2
58.1
58.0
57.9
57.6
57.4
b7.2
b7.1
57.0
57.0
56.9
56.9
56.9
57.0
57.0
57.0
57.0
57.0
57.0
57.0
57.0
57.0
56.9
56.8
56.5
56.2
56. 0
56.0
56,0.
S6.1
56.4
56.7
56.9
57.1
57.3
57.4
57.4
57.2
57.0
56. 9
S6.6
56.3
5A.--1
56.4
56.7
-------
SEC MPH
SEC MPH
SEC MHH
SEC MPH
SEC MPH
SEC MPH
SEC MPH
SEC MPH
400
401
402
403
404
405
406
407
4Q8
409
410
411
412
413
M4
415
416
417
418
419
420
421
422
423
424
425
426
427;
428
429
430
431
432
433
434
435
4 J6
437
43B
439
440
441
44?
443
444 '
445
446
447
448
449 .
57. 1
57.5
57.8
58.0
58.0
58.0
.58.0
5B.O
58.6
57.9
57.8
57.7
57.7
57 . 8
57.9
58.0
58.1
Sfl.4
58.9
59.1
5 9'. 4
59.8
59.9
59.9
59.8
59.6
b9.4
59.2
59.1 '
5^.0
58.9
bH.7
5H.6
58.5
5ri.4
5 ft. 4
5H.3
50.2
58.1
b8.0
57.9
57.9
57.9
57.9
57.9
58.0
5ft. 1 :
58.1
58.2
58.2 .
450
451 '
452
4S3
4S4
455
456
457'
4S8 v
459
460
461
462
463
4h4
465
466
A67
468
469
470
471
472
473
474
475
476
477
478
479
4ftO
481
482
483
484
485
486
487
488
4ft9
490
4('l
492
493
494
495
496
497
498
499
58.2 '
58.1
58.0
5ft. 0
58.0
b8.0
58.0
58.0
57.9
57.9
58.0
58.1
58. 1
58. 2
58. J
b8.3
58.3
'J8.2
56.1
S8.0
57.8
57.5
57.1
b7.0
56.6
56.1
b6.0
55,8
Sb.b
bb.2
5S.1
bh.O
54.9
54.9
b'4.9
54.9
54.9
54.9
S5.0
55.0
55.0
b5.0
SS.O
55.0
55.1
55.1
55.0
54.9
b'4.9
54. B
500
501
502
503
50<»
• 50b
506
507
508
S09
blO
511
b!2
513
514
515
bi6
517
S1H
M9
520
521
b2/?
S23
524
S2b
b2<»
b?7
528
529
530
S31
532
533
b.'j4
535
536
537
53ft
539
540
541
542
543
544
545
546
547
548
549
54.7
54.6
54.4
54.3
54.3
54.2
54.1
54.1
b4.1
54.0
54.0
54.0
54.0
54.0
54.0
b4.0
54.0
. 5t. 1
54.2
S4.b
54. H
54.9
5S.O
5S. 1
55.2
b'i.2
5S.3
5S.4
55.5
bS.6
5S.7
5'i.8
B'i.9
56.0
56.0
56.0
56.0
b6,0
56.0
56.0
56.0
bh.O
5h. 0
b6.0
5ft. 0
56.0
56.0
bb.9
55.9 '
55.9
550
b51
552
553
554
555
556
557
bS8
559
560
561
f>6?
563
5h4
565
566
567
56fl
569
570
571
572
573
574
575
576
577
57«
b79
580
581
5F2
583
5f 4
585
5ft6
587
5P3
b89
590
591
592
593
b94
595
596
597
593
599
• ss. a
5b.6
Sb.4
55.2
Sb.l
bS.O '
54.9
54.6
St. 4
54.2
54.1
53.8
S3. 4
53i3
SJ.l
52.9
52.6
52.4
52.2 .
52.1
52.0
52.0
52.0
52.0
52.1
52.0
b2.0
51.9
51.6
51.4
51.1
b'0.7
50.3
49.8
49.3
48.7
48.2
48. I
48. 0
48.0
48.1
48.4
48.9
49.0
4^.1
49.1
49.0
49.6
' 48.9
48.6
600
601
602
603
604
60b
606
607
608
60V
610
611
612
613
614
61b
616
617
618
619
620
621
622
623 .
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
48.3
48.0
47,9
47.8
47.7
47.9
48*3
49.0
49.1
49.0
48.9
4H.O
47.1
46.2
46.1
4h.l
46.2
46.9
47.8
49.0
49.7
sn.6
51.5
52.2
52.7
53.0
b3.6
54.0
54.1
54.4
54.7
5S.1
55.4
55. 4
55.0
54.5
53.6
b2.S
50.2
48. 2
46.5
46.2
46.0
46.0
46.3
46,8
47. b
4*. 2
43.8
49. b
' • 650
651
652
653
6b4
655
656
6b7
658
bb'9
660
661
662
663
664
66b
666
667
668
669
670
671
672
673
674
67b
676
. 677
678 •
6/9
680
681
682
. 683 .
684
685
686
687
688
689
690
691
692
693
694
69b
696
697
698
699
50.2
bO.7
51. 1
SI. 7
b2.2
52.5
52.1
51.6
M.I
51.0
51.0
51.1
bl.4
bl.7
52.0
b2.2
S2.5
b2.8
52.7
52.6
52.3
52.3
b2.4
52.5
52.7
52.7
b2.4
52.1
51.7
51. 1
• bO.5
bO.l
49.8
49.7
49.6 •
49.5
49.5.
49.7
50.0
50.2
50.6
•51.1
51.6
51.9
52.0
52.1
52.4
52.9
b'3.3
53.7
700
701
702
703
704
70S
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
54.2
54.5
54.8
55.0
55.5
55.9
56.1
56.3
56.4
56.5
56.7
56.9
57.0
57.3
57.7
58.2
58.8
59.1
59.2
59.1
58.8
58.5
53.1
57.7
57.3
57.1
56. a
56. S
56.2
55.5
54.6
54.1
53.7
53.2
52. '9
52.5
52.0
51.3
50.5
49.5
48.5
47.6
46.8
45.6
44.2
42. S
39.2
35.9
32.6
29.3
750 . 26.8
751 24.5
752 21.5
753 19.5
754 17.4
755 15.1
756 12.4
757 9.7
758 7.0
759 5.0
760 3.3
761 2.0
762 0.7
763 0.0
764 0.0
765 SAMPLE OFF
MON APR 22/74
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