motorcycles: myths, methodologies and momentum · 2018-05-02 · motorcycles and the mean drag...

Motorcycles: Myths, Methodologies

and Momentum

Detective Ken Strohmeyer

Scottsdale (Arizona) Police Department

Motorcycles:Myths, Methodologies and Momentum

So, you want to ride a Motorcycle?

▪ 29 times more likely to die than a passenger car occupant per vehicle mile driven

▪ 40% of the time it is a single vehicle crash

▪ 91% of all fatalities are male

▪ 68% of female fatalities are passengers

▪ 35% of all fatalities are over 50 years of age, 29% under 29 years of age

▪ Major Roads (main city streets) account for 62% of fatalities (12% Interstate)

▪ 48% of fatalities happen on the weekend

Motorcycles: Myths, Methodologies and Momentum

Occupant Fatality Rates by Vehicle Type, 2006 and 2015

Fatality Rate Motorcycle Light Trucks Passenger Car

2006

Per 100k registered 72.42 13.01 13.08

Per 100m miles traveled 40.14 1.1 1.11

2015

Per 100k registered 57.85 7.7 9.48

Per 100m miles traveled 25.38 0.72 0.89

Percent Change

Per 100k registered -20.10% -40.80% -27.50%

Per 100m miles traveled -36.8% -34.5% -19.8%


Source: U.S. Dept. of Transportation and National Highway Traffic Safety Administration

Wear a helmet or not, that is the question…

▪ 37% effective in preventing deaths

▪ 67% effective in preventing serious brain injury


Can we say a helmet will prevent fatalities?

What is the likelihood of the death if the rider

was wearing a helmet?

Myths: What have you heard?Motorcycles: Myths, Methodologies and Momentum

What have you been told?

▪ S curved skid marks are a sign of rear wheel braking

▪ Straight skids are a sign the front brake was used.


What have you been told?▪ “a single long straight skid mark may well be caused by a rear wheel skid generated while

the front brake was used (particularly if the motorcycle was still traveling at some speed at the end of the mark), but one can NOT be confident to the level of ‘more likely than not’, let alone ‘beyond a reasonable doubt’ that this is true. The ‘lazy-S’ shape clearly indicates a rear brake skid mark, but without additional supporting information does not indicate ‘to a reasonable degree of certainty’ that the front brake was not used. Similarly, a serpentine mark can be generated with front brake use, and is dependent on the operator's ‘body language’. Without testing the actual tires in use on particular the bike, or in some cases examining the tires themselves prior to their being driven on much, it may not be possible to confidently identify which tire made a particular short mark, or the vehicle's braking condition. With representative exemplar marks made under known conditions (rear only and front with rear) and using the actual tires in use on the accident unit, it would probably be possible to identify the braking condition at the time of the accident.”

▪ Bartlett, Wade, “Interpretation of Motorcycle Rear-Wheel Skid marks for Accident Reconstruction,” Proceedings, Fourth International Conference on Accident Investigation, Reconstruction, Interpretation and the Law, Vancouver BC, Canada, August 2001.

▪ “it is difficult to determine which brakes the rider used from only the observation of braking marks.”

▪ Dunn, A.L., et al, “Analysis of Motorcycle Braking Performance and Associated Braking Marks,” SAE Technical Paper 2012-01-0610, 2012, doi:10.4271/2012-01-0610.


What does that mean?

▪ Underestimating pre-crash braking▪ Standard Brakes (no ABS or Linking)

▪ Rear: 0.37 ± 0.6

▪ Front: 0.60 ± 0.16

▪ Both: 0.74 ± 0.15

▪ Bartlett, Wade, Baxter, Al, Robar, Neil, “Motorcycle Braking Tests: IPTM Data Through 2006,” Accident Reconstruction Journal, July/August 2007.


Average Deceleration (g)

Standard Integrated ABS Integrated

ABS

Linked

Rear 51% 70% 49% 121% 75%

Front 78% 89% 108% 111% 104%

Both 85% 107% 113% 119% 112%

Anderson, B., Baxter, A., Robar, N., “Comparison of Motorcycle Braking System Effectiveness,”

SAE Technical Paper 2010-01-0072, 2010, doi:10.4271/2010-01-0072

Roadway Automobile μ = 0.83

Average Deceleration (g)

Standard Integrated ABS Integrated

ABS

Linked

Rear 0.42 0.58 0.40 1.00 0.62

Front 0.60 0.73 0.89 0.92 0.86

Both 0.70 0.88 0.93 0.98 0.92

Anderson, B., Baxter, A., Robar, N., “Comparison of Motorcycle Braking System Effectiveness,”

SAE Technical Paper 2010-01-0072, 2010, doi:10.4271/2010-01-0072

Roadway Automobile μ = 0.83

What have you Heard?

▪ Drag Factor▪ At least 15 different studies have been conducted on a motorcycle sliding

on pavement. (published works)

▪ Tests were done with all types of “clad” and “unclad” motorcycles, in some the type was specified and in others it was not.

▪ Different test modalities

▪ Small data sets



▪ Drag Factor▪ Bartlett, et al (2007) summarized 162 IPTM tests using 99 different

motorcycles and the mean drag factor was 0.521 with a standard deviation of 0.140.

▪ They then combined this with other research to build a database of 386 tests. The mean was 0.480 with a standard deviation of 0.134.

▪ Separating out the data for fully clad motorcycle, the mean was 0.37 with a standard deviation of 0.08


Bartlett, W., Baxter, A., Robar, N., “Motorcycle Slide-to-Stop Tests: I.P.T.M. Data

Through 2006,” Accident Investigation Quarterly Vol. 46, Spring 2007.


▪ Drag Factor▪ Day and Smith (84) tested unclad motorcycles and determined a range of

0.45 – 0.58

▪ Peck, Focha, Gloekler (2014) tested motorcycles with plastic sliders the results were an average of 0.45 and a standard deviation of 0.09 which is more consistent with unclad motorcycles.

▪ Interesting to note that for the slider tests all had riders.


Day, T. and Smith, J., “Friction Factors for Motorcycles Sliding on Various

Surfaces,” SAE Technical Paper 840250, 1984, doi:10.4271/840250

Peck, L., Focha, W., Gloekler, T., “Motorcycle Sliding Friction for Accident

Investigation,” Proceedings of the 10th International Motorcycle Conference,

Institute for Motorcycle Safety, Essen, Germany, 2014.

386 Tests


0

50

100

150

200

250

300

350

400

450

0.0

15

431

54

0.0

50

411

10.0

85

390

66

0.1

20

370

22

0.1

55

349

78

0.1

90

329

34

0.2

25

308

899

0.2

60

288

459

0.2

95

268

019

0.3

30

247

579

0.3

65

227

139

0.4

00

206

699

0.4

35

186

259

0.4

70

165

818

0.5

05

145

378

0.5

40

124

938

0.5

75

104

498

0.6

10

084

058

0.6

45

063

618

0.6

80

043

177

0.7

15

022

737

0.7

50

002

297

0.7

84

981

857

0.8

19

961

417

0.8

54

940

977

0.8

89

920

537

0.9

24

900

096

0.9

59

879

656

0.9

94

859

216

1.0

29

838

776

1.0

64

818

336

Fre

qu

en

cy

Bin

Frequency

Average 0.519

std dev 0.140

Range 0.239 to 0.799

Day and Smith


050

100150200250300350400450

0.3

64

6

0.3

76

225

541

0.3

87

801

47

0.3

99

377

4

0.4

10

953

329

0.4

22

529

258

0.4

34

105

188

0.4

45

681

117

0.4

57

257

046

0.4

68

832

975

0.4

80

408

905

0.4

91

984

834

0.5

03

560

763

0.5

15

136

693

0.5

26

712

622

0.5

38

288

551

0.5

49

864

48

0.5

61

440

41

0.5

73

016

339

0.5

84

592

268

0.5

96

168

198

0.6

07

744

127

0.6

19

320

056

0.6

30

895

985

0.6

42

471

915

Fre

qu

en

cy

Bin

Frequency

avg 0.514

std dev 0.037

Range 0.440 to 0.589

020406080

100120140160180

0.4

50

003

967

0.4

58

528

297

0.4

67

052

627

0.4

75

576

957

0.4

84

101

287

0.4

92

625

617

0.5

01

149

947

0.5

09

674

277

0.5

18

198

607

0.5

26

722

937

0.5

35

247

267

0.5

43

771

597

0.5

52

295

927

0.5

60

820

257

0.5

69

344

587

0.5

77

868

917

Fre

qu

en

cy

Bin

Frequency

Clad Motorcycles


0

100

200

300

400

500

600

0.1

04

246

494

0.1

31

412

105

0.1

58

577

716

0.1

85

743

326

0.2

12

908

937

0.2

40

074

548

0.2

67

240

159

0.2

94

405

77

0.3

21

571

38

0.3

48

736

991

0.3

75

902

602

0.4

03

068

213

0.4

30

233

823

0.4

57

399

434

0.4

84

565

045

0.5

11

730

656

0.5

38

896

267

0.5

66

061

877

0.5

93

227

488

0.6

20

393

099

0.6

47

558

71

0.6

74

724

32

0.7

01

889

931

0.7

29

055

542

0.7

56

221

153

0.7

83

386

763

0.8

10

552

374

0.8

37

717

985

0.8

64

883

596

0.8

92

049

207

0.9

19

214

817

Fre

qu

en

cy

Bin

Frequency

Avg 0.370

Std Dev 0.079

Range 0.212 to 0.528

Sliders & Riders


0

100

200

300

400

500

6000.1

04

246

494

0.1

31

412

105

0.1

58

577

716

0.1

85

743

326

0.2

12

908

937

0.2

40

074

548

0.2

67

240

159

0.2

94

405

77

0.3

21

571

38

0.3

48

736

991

0.3

75

902

602

0.4

03

068

213

0.4

30

233

823

0.4

57

399

434

0.4

84

565

045

0.5

11

730

656

0.5

38

896

267

0.5

66

061

877

0.5

93

227

488

0.6

20

393

099

0.6

47

558

71

0.6

74

724

32

0.7

01

889

931

0.7

29

055

542

0.7

56

221

153

0.7

83

386

763

0.8

10

552

374

0.8

37

717

985

0.8

64

883

596

0.8

92

049

207

0.9

19

214

817

Fre

qu

en

cy

Bin

Frequency

Avg 0.451

Std Dev 0.090

Range 0.271 to 0.630

Summary


Avg Std Dev Range: 2SD

386 Tests 0.519 0.140 0.239 to 0.799

Day and Smith 0.514 0.037 0.440 to 0.589

Clad Motorcycles 0.370 0.079 0.212 to 0.528

Sliders & Riders 0.451 0.090 0.271 to 0.630

Methodologies: How Fast was he going?


Slide to Stop

𝑆 = 30𝑑𝑓

▪ Works well for:

▪ Single vehicle crashes with no impacts

▪ Motorcycle down and misses the other vehicle

▪ Parts separated from the motorcycle in the crash


Slide to Stop

𝑆 = 30𝑑𝑓

▪ Issues:

▪ Determining total distance

▪ Tumbling, sliding, multiple surfaces

▪ What drag factor to use


Slide to Stop


Slide to Stop


The motorcycle left tire marks leading up to the point where it went down and the

motorcycle and rider went in different directions. The riders first mark on the roadway

appears to be a helmet scuff approximately 66 feet from the last tire mark. The

motorcycle's first mark after the last tire mark is a gouge approximately 17 feet away.

The motorcycle left marks consistent with the crash bars sliding on the roadway. The rear

crash bar on the left side was heavily worn. The motorcycle went approximately 596 feet

before colliding with the barrier wall on the west side of the freeway. It went another 142

feet along the wall before coming to rest on its right side facing southeast.

Based on published data, metal sliding on asphalt generated a drag factor of 0.45 (f=0.45).

The total distance for the motorcycle is 738 feet. Using the basic speed formula, the

motorcycle was traveling approximately 99.81 mph. This is a minimum speed and does

not take into consideration the energy lost in the impact with the wall.

30𝑑𝑓 = 30 ∗ 738 ∗ 0.45 = 9963 = 99.81 𝑚𝑝ℎ

Slide to Stop


The rider traveled 397 feet from first mark to last mark. Data shows a

tumbling body generates a drag factor of 0.60 to 1.0 depending on the type

of clothing and how much tumbling versus sliding. In this case, a drag

factor of 0.80 (f=0.80) was used. The basic speed formula produces a

speed of 97.61 mph.

30𝑑𝑓 = 30 ∗ 397 ∗ 0.80 = 9528 = 97.61 𝑚𝑝ℎ

Slide to Stop


The speed at the start of the tire marks is slightly more complicated to determine. It is unsure how

much of a drag factor is generated during the time the tire is marking. Turning generates

approximately 20% braking efficiency while front wheel only braking generates approximately 60%

braking efficiency for a motorcycle. This will establish a range for the drag factor: 0.14 (turning) to

0.42 (front wheel braking) assuming a coefficient of friction for the roadway of 0.70. The tire marks

prior to the motorcycle going down were 352 feet. The combined speed formula produces a speed

at the beginning of the tire marks for the motorcycle of 106.95 mph to 119.98 mph. This assumes no

throttle was being applied.

𝑆𝑜2 + 30𝑑𝑓 = 99.812 + (30 ∗ 352 ∗ 0.14) = 11440.4 = 106.95 𝑚𝑝ℎ

𝑆𝑜2 + 30𝑑𝑓 = 99.812 + (30 ∗ 397 ∗ 0.42) = 14397.2 = 119.98 𝑚𝑝ℎ

Searle

𝑆 =30𝑑𝑓

cos 𝜃 + 𝑓 sin 𝜃

▪ Rider separates from the motorcycle:

▪ How much interaction with the motorcycle?

▪ Launch angle?

▪ Passenger?


𝑆𝑀𝑖𝑛 =30𝑑𝑓

1 + 𝑓2

𝑆𝑀𝑎𝑥 = 30𝑑𝑓

Speed from Gear

▪ Max speed for that gear:

▪ Could the motorcycle be going that fast?

▪ What is the fastest speed attainable for that gear?

▪ Stuck RPM needle


Speed from Gear


𝑆𝑟𝑜𝑎𝑑,𝑚𝑎𝑥 =𝑆𝑟𝑝𝑚,𝑚𝑎𝑥

𝑟𝑝𝑟 ∗ 𝑟𝑓𝑟 ∗ 𝑟𝑖∗ 𝑐𝑟𝑒𝑎𝑟 ∗

60

5280

𝑆𝑟𝑜𝑎𝑑,𝑚𝑎𝑥 = 𝑈𝑝𝑝𝑒𝑟 𝑙𝑖𝑚𝑖𝑡 𝑜𝑓 𝑠𝑝𝑒𝑒𝑑 𝑖𝑛 𝑡ℎ𝑒 𝑔𝑒𝑎𝑟 𝑖𝑛 𝑞𝑢𝑒𝑠𝑡𝑖𝑜𝑛

𝑆𝑟𝑝𝑚,𝑚𝑎𝑥 = 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑒𝑛𝑔𝑖𝑛𝑒 𝑠𝑝𝑒𝑒𝑑 𝑖𝑛 𝑅𝑃𝑀𝑠

𝑟𝑝𝑟 = 𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑟𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑖𝑜

𝑐𝑟𝑒𝑎𝑟 =2Π 𝑟𝑟𝑒𝑎𝑟

12= 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑟𝑜𝑙𝑙𝑒𝑑 𝑝𝑒𝑟 𝑟𝑒𝑣𝑜𝑙𝑢𝑡𝑖𝑜𝑛 𝑜𝑓 𝑡ℎ𝑒 𝑟𝑒𝑎𝑟 𝑡𝑖𝑟𝑒 𝑔𝑖𝑣𝑒𝑛 𝑡ℎ𝑒 𝑟𝑎𝑑𝑖𝑢𝑠 𝑜𝑓 𝑡ℎ𝑒 𝑟𝑒𝑎𝑟 𝑡𝑖𝑟𝑒 (𝑟𝑟𝑒𝑎𝑟)

𝑟𝑓𝑟 = 𝐹𝑖𝑛𝑎𝑙 𝑅𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑖𝑜

𝑟𝑖 = 𝑔𝑒𝑎𝑟 𝑟𝑎𝑡𝑖𝑜 𝑜𝑓 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑔𝑒𝑎𝑟

Speed from Gear

Toyota Tundra pulls out in front of a Suzuki SV650s.

The rider of the M/C somehow has the motorcycle

sideways at impact with the truck’s front axle.


What does that mean?


Can you do that?


▪ The truck registered a lateral Δv of 8.9 mph. The truck was basically stopped in the lateral direction so all of the energy to cause that would have come from the motorcycle.

▪ The motorcycle Δv can be determined by the following formula:

∆𝑉2=𝑊1∆𝑉1

𝑊2

W1 = 5295 lb

W2=524 lb

ΔV1=8.9 mph

∆𝑉2=𝑊1∆𝑉1

𝑊2=

5295∗8.9

524= 89.93 𝑚𝑝ℎ

Can you do that?


▪ This would be a minimum speed which ignores restitution and other ground forces.

▪ The motorcycle was found to be in third gear

▪ rpr = 2.088

▪ rfr = 3.000

▪ ri = 1.380

▪ Gear Final drive = 8.644

▪ Max power 9000 rpm

▪ rrear = 12.25 inches

Can you do that?


𝑆𝑟𝑜𝑎𝑑,𝑚𝑎𝑥 =𝑆𝑟𝑝𝑚,𝑚𝑎𝑥

𝑟𝑝𝑟 ∗ 𝑟𝑓𝑟 ∗ 𝑟𝑖∗ 𝑐𝑟𝑒𝑎𝑟 ∗

60

5280

𝑆𝑟𝑜𝑎𝑑,𝑚𝑎𝑥 =9000

2.088 ∗ 3.000 ∗ 1.380∗ 6.414 ∗

60

5280

𝑐𝑟𝑒𝑎𝑟 =2Π 𝑟𝑟𝑒𝑎𝑟

12=2 ∗ 3.14 ∗ 12.25

12= 6.414 𝑓𝑒𝑒𝑡

𝑆𝑟𝑜𝑎𝑑,𝑚𝑎𝑥 = 1041.14 ∗ 6.414 ∗ 0.01136 = 75.88 𝑚𝑝ℎ

Baxter, Albert T., Motorcycle Crash Investigation,

Institute of Police Technology and Management, 2017.

Can you do that?


𝑆𝑟𝑜𝑎𝑑,𝑚𝑎𝑥 = 1041.14 ∗ 6.414 ∗ 0.01136 = 75.88 𝑚𝑝ℎ

∆𝑉2=𝑊1∆𝑉1

𝑊2=

5295∗8.9

524= 89.93 𝑚𝑝ℎ

Can you do that?


Can you do that?


The speed from gear formulas give us a reason to look

elsewhere:

After a discussion with Rick Ruth, this does not work

because of the way the EDR records data in this type of

crash

Energy Methods

▪ Wheelbase Reduction

▪ Wheelbase Reduction + maximum car crush

▪ CRASH style analysis (force balancing)


Momentum: Shouldn’t this be under myths?


Momentum


Motorcycle Speed Estimates Using Conservation of

Linear and Rotational Momentum

Bruce F. McNally, ACTAR McNally and Associates Accident Reconstruction Services, LLC

Wade Bartlett, PE, ACTAR Mechanical Forensics Engineering Services, LLP

Presented at the 20th Annual Special Problems in Traffic Crash Reconstruction at the Institute of

Police Technology and Management, University of North Florida, Jacksonville, Florida, April

15-19, 2002

Momentum▪ Fricke and Riley indicate in Topic 874 of the Traffic Accident Investigation Manual

that “occasionally a momentum analysis is attempted” and that this technique “rarely… works well” in accurately estimating the speed of the motorcycle.

▪ In 1990, Brown and Obenski write that a momentum analysis “can sometimes be used in motorcycle accidents,” and give a graphical example of a momentum vector diagram of a motorcycle/automobile collision.

▪ In 1994, Obenski further clarifies this position by stating “Generally it is tricky to use momentum analysis in accidents between vehicles with a big weight difference,” but gives the same graphical example as in his previous work. Obenskispecifically cautions against using a momentum analysis where the automobile has been moved very little after impact with the motorcycle.

▪ In 1990, Niederer wrote about techniques that may be used to reconstruct motorcycle/vehicle collisions, with the emphasis of the paper on the use of conservation of linear and angular momentum. Niederer specifically cautions that “due to the often unfavourable mass ratio an accurate reconstruction may be impeded,” but concludes that when used cautiously, the use of momentum and other available information “represents a powerful tool for motorcycle-vehicle collision reconstruction.”


Momentum

▪ Redirection of both Vehicle’s Center of Mass

▪ Uncontrolled rest of both vehicles

▪ Momentum not more than 10 to 1 difference


Momentum Case #1

▪ Vehicle # 1 was stopped on Scottsdale Road at Jomax Road in

the n/b left turn lane. Vehicle # 2 was traveling s/b through a

green signal in the # 1 lane of Scottsdale Road at Jomax Road.

Vehicle # 1 started to turn w/b onto Jomax and stopped in the # 1

s/b lane of Scottsdale Road. The front of Vehicle # 2 collided with

the front of Vehicle # 1.


Case #1


Momentum Case #1


Momentum Case #1

▪ Audi A7: d=9ft, f=0.75, SD=0.05, S2=0 mph, W=4408 lbs

▪ Honda ST1300: d=40ft, f= 0.37 SD=0.08, W=845 lbs

▪ Rider: d=148 ft, fSearle=0.66, W=290 lbs


Momentum Case #1


Audi Avg Std Dev

distance 9 0.2

drag factor 0.7 0.05

weight 4408 200

Honda

distance 40 0.8

drag factor 0.37 0.08

weight 845 38

Rider

distance 148 2.96

drag factor Searle 0.66

weight 290 13

Audi Honda Rider Momentum

d f Sa W WSa d f Sm W WSm d Sr W WSr Whr Smr

8.854763 0.634237 12.98 4384.068 56905.21 39.81354 0.331856 19.90906 848.9094 16900.99 150.635 54.61293 308.3878 16841.96 1157.297 78.32746829

8.819332 0.644674 13.06016 4472.044 58405.62 39.8416 0.33367 19.97044 835.7541 16690.38 147.075 53.96374 304.5473 16434.51 1140.301 80.26869423

8.562449 0.68987 13.312 4419.106 58827.11 38.93084 0.343828 20.03909 870.6991 17448.02 142.8225 53.17786 283.2169 15060.87 1153.916 79.15307868

8.954813 0.68125 13.52827 4932.029 66721.81 40.18345 0.396541 21.86392 848.2962 18547.08 150.4002 54.57036 281.9552 15386.4 1130.251 89.05566213

8.877786 0.720373 13.85133 4331.538 59997.57 39.18321 0.332704 19.77605 827.1514 16357.79 147.301 54.00518 301.7315 16295.07 1128.883 82.07266441

Momentum Case #1


0

100

200

300

400

500

60056

.42

086

535

57

.80

848

559

59

.19

610

583

60

.58

372

606

61

.97

134

63

63

.35

896

654

64

.74

658

678

66

.13

420

702

67

.52

182

725

68

.90

944

749

70

.29

706

773

71

.68

468

797

73

.07

230

82

74

.45

992

844

75

.84

754

868

77

.23

516

892

78

.62

278

915

80

.01

040

939

81

.39

802

963

82

.78

564

987

84

.17

327

01

85

.56

089

034

86

.94

851

058

88

.33

613

082

89

.72

375

105

91

.11

137

129

92

.49

899

153

93

.88

661

177

95

.27

423

201

96

.66

185

224

98

.04

947

248

Fre

qu

en

cy

Bin

Frequency

Average 82.81244

Std Dev 4.180016

Range :2d 74.45241 to 91.17247

Time / Distance Case #1


Time Distance Speed

Time 2.498213 332.5886 90.81213

Range 2.43 2.52 2.444291 325.0327 90.70689

2.499202 336.8248 91.93242

Distance Avg Std Dev 2.486576 322.6992 88.52423

315 15.75 2.438465 337.8767 94.5165

2.494786 320.4267 87.61158

2.502809 315.0139 85.85549

0

100

200

300

400

500

600

700

45

.40

332

752

48

.30

113

102

51

.19

893

451

54

.09

673

801

56

.99

454

15

59

.89

234

5

62

.79

014

849

65

.68

795

198

68

.58

575

548

71

.48

355

897

74

.38

136

247

77

.27

916

596

80

.17

696

946

83

.07

477

295

85

.97

257

645

88

.87

037

994

91

.76

818

343

94

.66

598

693

97

.56

379

042

10

0.4

615

939

10

3.3

593

974

Fre

qu

en

cy

Bin

Frequency

Average 86.79066

Std Dev 4.466936

Range 2d 77.85678 to 95.72453

Momentum v Time / Distance


0

100

200

300

400

500

600

700

45

.40

332

752

47

.81

816

377

50

.23

300

001

52

.64

783

626

55

.06

267

25

57

.47

750

875

59

.89

234

5

62

.30

718

124

64

.72

201

749

67

.13

685

373

69

.55

168

998

71

.96

652

622

74

.38

136

247

76

.79

619

871

79

.21

103

496

81

.62

587

12

84

.04

070

745

86

.45

554

369

88

.87

037

994

91

.28

521

619

93

.70

005

243

96

.11

488

868

98

.52

972

492

10

0.9

445

612

10

3.3

593

974

Fre

qu

en

cy

Bin

Frequency

Average 86.79066

Std Dev 4.466936

Range 2d 77.85678 to 95.72453

0

100

200

300

400

500

60056

.42

086

535

58

.15

539

065

59

.88

991

595

61

.62

444

124

63

.35

896

654

65

.09

349

184

66

.82

801

713

68

.56

254

243

70

.29

706

773

72

.03

159

303

73

.76

611

832

75

.50

064

362

77

.23

516

892

78

.96

969

421

80

.70

421

951

82

.43

874

481

84

.17

327

01

85

.90

779

54

87

.64

232

07

89

.37

684

6

91

.11

137

129

92

.84

589

659

94

.58

042

189

96

.31

494

718

98

.04

947

248

Fre

qu

en

cy

Bin

Frequency

Average 82.81244

Std Dev 4.180016

Range :2d 74.45241 to 91.17247

Momentum Case #2


Momentum Case #2


This Collision involved two vehicles: #1 was a blue 2008 Pontiac G6. #2 was a white 2012 Honda

ST1300 Police Motorcycle.

Damage to both units along with roadway evidence placed the area of impact in the eastbound #1

lane of Chandler Blvd. The motorcycle was believed to have been stopped on Chandler Blvd at

the intersection of Pennington Dr. when the G6 struck it from behind.

Momentum Case #2


Momentum Case #2


𝑆𝐺6 =𝑊𝐺6𝑆3 +𝑊𝑀𝐶𝑆4

𝑊𝐺6

200

Momentum Case #2



𝑊𝐺6

𝑊𝐺6 = 3450 𝑙𝑏𝑠

𝑊𝑀𝐶 = 1130 𝑙𝑏𝑠

𝑆3 = 𝑆𝐶𝐷𝑅 − ∆𝑉 = 57 − 14 = 43𝑚𝑝ℎ

𝑆4 = 53.93

𝑆𝐺6 =3450 ∗ 43 + (1130 ∗ 53.93)

3450

𝑆𝐺6 =208240

3450

𝑆𝐺6 = 60.35 𝑚𝑝ℎ

Momentum Case #2



𝑊𝐺6

𝑊𝐺6 = 3450 𝑙𝑏𝑠

𝑊𝑀𝐶 = 930 𝑙𝑏𝑠

𝑆3 = 𝑆𝐶𝐷𝑅 − ∆𝑉 = 57 − 14 = 43𝑚𝑝ℎ

𝑆4 = 53.93

𝑆𝐺6 =3450 ∗ 43 + (930 ∗ 53.93)

3450

𝑆𝐺6 =197640

3450

𝑆𝐺6 = 57.28 𝑚𝑝ℎ

Momentum Case #2


𝑆𝐺6 = 57.28 𝑚𝑝ℎ

Special Thanks to:


Nathan Rose

“Motorcycle Crash Reconstruction”

By Nathan Rose

Forthcoming Book from the Society of Automotive Engineers

Due out late 2018

motorcycles: myths, methodologies and momentum · 2018-05-02 · motorcycles and the mean drag...

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