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Transcript of WREX2016 Conference Presentation - FRSI Searle Presentation, 2009 IPTM Special Problems Conference...
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 1
WREX 2016World Reconstruction Exposition
“The Effects of Carry Distance, Takeoff Angles, FrictionValues and Horizontal Speed Loss Upon First GroundContact on Pedestrian (Cyclist) Crashes”
Orlando, FloridaMay 2 - 6, 2016
Presented by:
Mike W. ReadeGraphic by: Virtual CRASH
Backgrounds (Mike W. Reade, CD)
◦ 1974 –2000
◦ Adjunct Instructor – 1993 to Present
◦ Pedestrian Training, Testing & Research 2000 to Present
◦ Consulting – 2000 to Present
2
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 2
Presentation Content
Typical pedestrian (cyclist) crash phases. Effects of pedestrian carry distance. Effects of pedestrian takeoff angles. Effects of pedestrian friction values. Effects of horizontal speed loss upon
ground impact.
3
Presentation Content
Effects of vertical height differences between takeoff & landing.
Pedestrian drop testing. Discuss the effects of roadway slope. Head contact/impact speed estimates. Discuss the overall effects when
considering all factors.
4
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 3
A Typical Pedestrian Crash[1] (Video)
Crash Test 1 = 21.5 mph (34.6 kph) Crash Test 2 = 22.5 mph (36.3 kph)
5
A Typical Pedestrian Crash[2]
Pre-CrashPhase
ImpactPhase
CarryDistancePhase
AirbornePhase
HorizontalSpeed Loss
Phase
PedestrianSlidingPhase
6
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 4
Pre-Crash Phase/Analysis
Slide to stop method in cases where vehicle is braking before impact.
Results can be combined with the pedestrian projectile analysis.
V 2 gd
7
Pre-Crash Phase/Analysis
Any pre-braking is combined with pedestrian projectile analysis.
8
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 5
Impact Phase
First contact with pedestrian.
9Virtual CRASH Graphic (www.vcrashusa.com)
Pedestrian Trajectories (Top View)
10Virtual CRASH Graphic (www.vcrashusa.com)
Forward Projection Trajectory
Wrap Trajectory
Vehicle Speed = 30 mph (48 km/h) Searle Min = 78.9 % of Vehicle Speed
Throw D: 51.31 ft/15.63 m)
Throw D: 39.89 ft (12.15 m)Searle Min: 23.6 mph (38.1 km/h)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 6
Pedestrian Trajectories (Prospective View)
11Virtual CRASH Graphic (www.vcrashusa.com)
Vehicle Speed = 30 mph (48 km/h)
IPTM Controlled Tests[3, 8]
12Virtual CRASH Graphic (www.vcrashusa.com)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 7
Combined Speed Analysis
Combined Speed Method:
Where:◦ V1 = Pre-Crash Speed Loss◦ V2 = Pedestrian Projectile Results
2 2C 1 2V V V
13
Projectile Throw Analysis
Searle Minimum Formula[4, 5, 6]:◦ Validated for many years though testing.◦ Can be adjusted to suit various situations.
Results underestimate vehicle’s speed.
◦ Pedestrian acquires < 100% of vehicle’s speed unless a forward projection trajectory.
min 22 gSV1
14
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 8
Projectile Throw Analysis
min 22 gSV1
Where:
µ = Ped friction valueg = Gravitational accelerationS = Total throw distance
µ
S
15
Pedestrian Throw Analysis
Example: [Throw D (S) = 100ft (30.48m), µ = 0.66]
min 22 gSV1
min 22 0.66 32.2 100V
1 0.66
minV 54.41 fps 37.1mph
min 22 gSV1
min 22 0.66 9.81 30.48V
1 0.66
minV 16.58 m / s 59.69 kph
Imperial: Metric:
16
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 9
Carry Distance Phase (0:00 sec)
17Virtual CRASH Graphic (www.vcrashusa.com)
What is the pedestrian’s carry distance?
Carry Distance Phase (0:03 sec)
18Virtual CRASH Graphic (www.vcrashusa.com)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 10
Carry Distance Phase (0:06 sec)
19Virtual CRASH Graphic (www.vcrashusa.com)
Carry Distance Phase (0:09 sec)
20Virtual CRASH Graphic (www.vcrashusa.com)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 11
Carry Distance Phase (0:12 sec)
21Virtual CRASH Graphic (www.vcrashusa.com)
Carry Distance Phase (0:15 sec)
22Virtual CRASH Graphic (www.vcrashusa.com)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 12
Carry Distance Phase (0:18 sec)
23Virtual CRASH Graphic (www.vcrashusa.com)
Carry Distance Phase (0:21 sec)
24Virtual CRASH Graphic (www.vcrashusa.com)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 13
Carry Distance Phase (0:24 sec)
25Virtual CRASH Graphic (www.vcrashusa.com)
Carry Distance Phase (0:27 sec)
26Virtual CRASH Graphic (www.vcrashusa.com)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 14
Carry Distance Phase (0:30 sec)
27Virtual CRASH Graphic (www.vcrashusa.com)
Head Tracking (0:30 sec)
28Virtual CRASH Graphic (www.vcrashusa.com)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 15
Carry Distance Phase[1]
29
Carry Distance Phase (1/30 frames)
30
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 16
Carry Distance Phase (2/30 frames)
31
Carry Distance Phase (3/30 frames)
32
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 17
Carry Distance Phase (4/30 frames)
33
Carry Distance Phase (5/30 frames)
34
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 18
Carry Distance Phase (6/30 frames)
35
Carry Distance Phase (7/30 frames)
36
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 19
Carry Distance Phase (8/30 frames)
37
Carry Distance Phase (9/30 frames)
38
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 20
Carry Distance Phase (10/30 frames)
39
Carry Distance Phase (11/30 frames)
40
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 21
Carry Distance Phase (12/30 frames)
41
Carry Distance Phase (13/30 frames)
42
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 22
Carry Distance Phase (14/30 frames)
43
Carry Distance Phase (15/30 frames)
44
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 23
Carry Distance Phase (16/30 frames)
45
Carry Distance Phase (17/30 frames)
46
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 24
Carry Distance Phase (18/30 frames)
47
Carry Distance Phase (19/30 frames)
48
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 25
Carry Distance Phase (20/30 frames)
49
Carry Distance Phase (21/30 frames)
50
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 26
Carry Distance Phase (22/30 frames)
51
Carry Distance Phase (23/30 frames)
52
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 27
Carry Distance Phase (24/30 frames)
53
Carry Distance Phase (25/30 frames)
54
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 28
Carry Distance Phase (26/30 frames)
55
Carry Distance Phase (27/30 frames)
56
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 29
Carry Distance Phase (28/30 frames)
57
Carry Distance Phase (29/30 frames)
58
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 30
Carry Distance Analysis[6]
min 2
2 g dSV
1
µ
Where:
µ = Ped friction valueg = Gravitational accelerations = Total throw distanced = Carry distance
d
S
Reference: Searle Presentation, 2009 IPTM Special Problems ConferenceOrlando, Florida – April 20 to 24, 2009 59
Carry Distance Analysis
Searle research[6]:
◦ 2.62 ft (0.8 m)
Becker/Reade research[1]:
◦ Data from 126 wrap tests.◦ 3.90 ft (1.19 m) – [s.d. 1.63 ft (0.50 m)]
Usually the carry distance is unknown. Throw D (S) is reduced by Carry D (d).
min 2
2 g dSV
1
60
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 31
Airborne Phase (0:25 sec)
Starts after separating from the vehicle.
61Virtual CRASH Graphic (www.vcrashusa.com)
Airborne Phase (0:50 sec)
62Virtual CRASH Graphic (www.vcrashusa.com)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 32
Airborne Phase (0:75 sec)
63Virtual CRASH Graphic (www.vcrashusa.com)
Airborne Phase (0:92 sec)
64Virtual CRASH Graphic (www.vcrashusa.com)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 33
Airborne Analysis
Could use the airborne formula, if…◦ Vertical height (h) is known. Use “-” h for landing
higher than takeoff.◦ Takeoff angle (θ) is measured counter clockwise.◦ Horizontal distance (D) is between separation
and first touchdown on road.
2.73 DSCos h D Tan
“Fundamentals of Traffic Crash Reconstruction” Vol. 2 of the Traffic Crash Reconstruction Series Daily * Shigemura * Daily © 2006, ISBN 978-1-884566-63-9
7.96 DS
Cos h D Tan
Imperial: Metric:
65
Airborne AnalysisWhere:
D= Horizontal distanceθ = Takeoff angleh = Lands lower
D hθ
2.73 DSCos h D Tan
“Fundamentals of Traffic Crash Reconstruction” Vol. 2 of the Traffic Crash Reconstruction SeriesDaily * Shigemura * Daily © 2006, ISBN 978-1-884566-63-9
Imperial: Metric:
7.96 DS
Cos h D Tan
66
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 34
Airborne Analysis
?
Since it is difficult in most cases to determine where the pedestrian first touches down on the road surface, this method is normally not used.
The other challenge is deciding upon what takeoff angle to use.
θ = ?
67
θ = ?
Airborne Analysis
Pedestrian Takeoff Angles[1]:◦ Becker/Reade research[1] based upon 126 wrap
crash tests and increasing as more tests are entered.
Mean takeoff θ: 6.3 deg (s.d. 3.3 deg)
Wrap Tests
68
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 35
Airborne Analysis
cSwing Golf Software. ($149 US)
All Tests Bike Tests
69
Airborne Analysis
µ
Where:
µ = Ped friction valueg = Gravitational accelerationS = Total throw distanceθ = Takeoff angle
S
2 gSV
Cos Sin
θ
70
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 36
Horizontal Speed Loss Phase
Pedestrian Crash Testing[1,9]
71
Crash test data:Mean: 6.53 mph / 10.5 km/hs.d. 1.11 mph / 1.78 km/h
Projectile vs. Sliding Analysis[1, 7, 9]
µ
Where:
µ = Ped friction valueg = Gravitational accelerationS = Total throw distanced = Ped sliding distance
S
min 22 gSV1
vs:
d
V 2 gd
72
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 37
Projectile vs. Slide Speed Analysis
Here, the pedestrian’s slide to stop results are less than the Searle Minimum results.
Reason?◦ Due to a horizontal speed loss upon pedestrian
ground impact.
min 22 gSV1
vs: V 2 gd
73
Horizontal Speed Loss Analysis
Horizontal Speed Loss on Ground Impact:◦ Becker/Reade research[1] based upon 126 wrap
crash tests and increasing as more tests are entered.
Mean: 6.53 mph (10.51 km/h)
s.d. 1.06 mph (1.70 km/h)
HorizontalSpeed Loss ?
74
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 38
Horizontal Speed Loss Analysis
θ
H
ov v sin
2V v 2gH
v
µ
Where:
vo = Original takeoff velocityv = Vertical velocity on takeoffθ = Takeoff angle (degrees)µ = Ped friction valueg = Gravitational accelerationH = Height of C/M
75
Horizontal Speed Loss Analysis
θ
Where:
vo = 44 fps (30 mph)v = Vertical velocity on takeoffθ = 10 degreesµ = 0.66g = 32.2 f/s/sH = 3 ft
H
v 44 0.1736 7.64 fps
2V 0.66 7.64 2 32.2 3 10.46 fps 7.14mph
v
µ
V = 10.46 fps
Example:
76
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 39
Pedestrian Sliding Phase
Pedestrian Sliding Analysis[1, 7, 9]
77
Pedestrian Sliding Analysis
µ
Where:
µ = Ped friction valueg = Gravitational accelerationd = Ped sliding distance
d
V 2 gd
78
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 40
Pedestrian Sliding Analysis
If you are able to establish the pedestrian’s first touchdown as ground contact starts, then your results will underestimate the vehicle’s impact speed.
Because of horizontal speed loss upon ground impact.
Acquires < 100% of vehicle speed !
V 2 gd
79
Pedestrian Sliding Evidence Only? If you are only able to establish the
pedestrian’s total sliding distance, the pedestrian sliding results will underestimatethe vehicle’s impact speed.
So, determine the horizontal speed loss upon ground impact.
Add the two speed values together[1, 6, 7, 9]. The result will approximate the projectile’s
airborne speed.
80
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 41
Pedestrian Friction Values[1]
81
Pedestrian Friction Values
Searle’s Sandbag Method[6]: ◦ Dry Surface: 0.715 Mean
◦ Wet Surface: 0.695 Mean
◦ Frost Surface: 0.40 Mean
◦ Overall Value: 0.695 Mean
Reference: Searle Presentation, 2009 IPTM Special Problems ConferenceOrlando, Florida – April 20 to 24, 2009 82
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 42
Searle’s Sandbag Method[6]
Suggested Protocol:◦ Use sandbag with a weight of about 33 lb / 15 kg, made of
denim material.
◦ Wrap sandbag in appropriate clothing material worn by pedestrian.
◦ Weigh sandbag and attach a long line of 4 meters (13 feet).
◦ Attach to back of vehicle and “slowly” ease forward at walking pace.
◦ Perform several tests and determine average pull force.
◦ Weigh sandbag again and use mean value.
◦ Correct for slight upward pull angle as attached to vehicle.
Reference: Searle Presentation, 2009 IPTM Special Problems ConferenceOrlando, Florida – April 20 to 24, 2009 83
Searle’s Sandbag Method
Reference: Searle Presentation, 2009 IPTM Special Problems ConferenceOrlando, Florida – April 20 to 24, 2009
Sandbag Tests Protocol:
◦ The resulting value incorporates the surface gradient and no further correction is required.
( )( )=
- ×
Pμ
hW P l
Where:P = Average PullW = Sandbag Weighth = Height of Attachment Pointl = Length of Rope/Wire
84
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 43
Searle’s Sandbag Method
Reference: Searle Presentation, 2009 IPTM Special Problems ConferenceOrlando, Florida – April 20 to 24, 2009
Denim Sandbag Test Example:Sandbag 1st Weight: 33 lbSandbag 2nd Weight: 32 lbSandbag Mean Weight (W): 32.5 lbSandbag Pulls (P): 21, 23, 25, 22, 24 (Avg: 23)Attachment Height (h): 14 inches (1.16 feet)Rope Length (l): 12 feet (144 inches)
Determine the adjusted friction value to use for your pedestrian sliding on the surface you tested.
0.759 vs. 0.707.....( )( )=
- ×
Pμ
hW P l
85
Searle’s Sandbag Method
Reference: Searle Presentation, 2009 IPTM Special Problems ConferenceOrlando, Florida – April 20 to 24, 2009
Denim Sandbag Test Example:Sandbag 1st Weight: 33 lbSandbag 2nd Weight: 32 lbSandbag Mean Weight (W): 32.5 lbSandbag Pulls (P): 19, 20, 17, 19, 18 (Avg: 18.6)Attachment Height (h): 14 inches (1.16 feet)Rope Length (l): 12 feet (144 inches)
Determine the adjusted friction value to use for your pedestrian sliding on the surface you tested.
0.605 vs. 0.572.....( )( )=
- ×
Pμ
hW P l
86
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 44
Pedestrian Friction Values
Hill’s Asphalt Friction Values[6]:◦ Serge Jacket & Trousers: 0.702
◦ Body Warmer & Trousers: 0.723
◦ Nylon Jacket & Trousers: 0.567
◦ Woollen Boiler Suit: 0.750
◦ Rubber Jacket/Trousers: 0.735
◦ Mean Value: 0.695
◦ Std. Dev.: 0.073
Reference: Searle Presentation, 2009 IPTM Special Problems ConferenceOrlando, Florida – April 20 to 24, 2009 87
Pedestrian Friction Values
Bovington Friction Results[6]: ◦ Nylon Rain Suit: 0.532
◦ Leather M/C Suit: 0.562
◦ Nylon M/C Suit: 0.608
◦ Woollen Boiler Suit: 0.633
◦ Rubber Jacket/Trousers: 0.612
◦ Mean Value: 0.584
◦ Std. Dev.: 0.039
Reference: Searle Presentation, 2009 IPTM Special Problems ConferenceOrlando, Florida – April 20 to 24, 2009 88
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 45
Pedestrian Friction Values
Test Dummy Friction Results[1]: ◦ Albuquerque, NM Class: 0.67
◦ Fort McCoy, WI Class: 0.59
◦ Augusta, ME Class: 0.50
◦ Sewell, NJ Class: 0.54
◦ Scotch Plains, NJ Class: 0.59
◦ Narragansett, RI Class: 0.66
◦ Mean Value: 0.59
◦ Std. Dev.: 0.08
Reference: IPTM Test Dummy Friction TestingAs part of Pedestrian Courses 89
Pedestrian Friction Values
Winter Pedestrian Testing[9]: ◦ Wet Asphalt Surface: 0.58
◦ Snow/Slush Mixture: 0.53
◦ Packed Snow Mixture: 0.45
◦ Mean Value: 0.52
◦ Std. Dev.: 0.03
Reference: CATAIR Winter Pedestrian Testing ResultsRiverview, NB Canada – January 2011
90
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 46
Pedestrian Friction Values Overall Mean Values: ◦ Searle’s Sandbag Method: 0.69 Mean
◦ Searle Suggested Value: 0.66 (Asphalt)
◦ Searle Suggested Value: 0.70 (Asphalt)
◦ Hill’s Friction Results: 0.69 Mean
◦ Bovington’s Friction Results: 0.58 Mean
◦ IPTM Dummy Results: 0.59 Mean
◦ IPTM Crash Tests (139 tests): 0.61 Mean
◦ CATAIR Winter Testing: 0.52 Mean
◦ Mean Value: 0.63
◦ Std. Dev.: 0.0691
Pedestrian Slide to Stop Results
Example: (Slide D = 65 ft (19.81 m), µ = Ped Values)◦ Searle Sandbag Tests (0.69): 36.6 mph (59.0 km/h)
◦ Hill’s Friction Results (0.69): 36.6 mph (59.0 km/h)
◦ Bovington’s Results (0.58): 33.6 mph (55.1 km/h)
◦ Searle’s Suggested µ (0.66): 35.8 mph (57.7 km/h)
◦ IPTM Ped Classes (0.59): 33.9 mph (54.6 km/h)
◦ IPTM Crash Testing (0.61): 34.4 mph (55.4 km/h)
◦ CATAIR Winter Tests (0.52): 31.8 mph (51.2 km/h)
(Overall Mean “ µ ” Value of All Results: 0.63)
92
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 47
Projection Efficiency[1, 4, 5, 6, 7, 9]
Pedestrian Speed Acquired From Vehicle:◦ Becker/Reade research[1] based upon 126 wrap
crash tests and increasing as more tests are entered.
Mean Vehicle %: 87 % Searle(1983) %: 77.5 %
Wrap Tests
(Vehicle Impact Speed vs. Searle Min Results) 93
Pedestrian Crash Test Data
µ = 0.66
S = 56 ft
min 22 gSV 27.76 mph1
d = 21 ft
SLIDEV 2 gd 20.39 mph
Impact: 35.29 mph
35.2927.76% 78.6 %
35.2920. 5 739 %% 7.
(Horizontal Speed Loss: ?)
94
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 48
Both results underestimate the vehicle’s impact speed because:◦ Searle Min Speed vs. Vehicle Speed. (78.6 %)
◦ Ped Slide Speed vs. Searle Min Speed. (73.4 %)
◦ Ped Slide Speed vs. Vehicle Speed. (57.7 %)
Pedestrian Crash Test Data
Impact: 35.29 mph Sliding: 20.39 mph
95
Special Considerations
Change in vertical height between takeoff and touchdown[1, 5, 6].
Roadway slope[5, 6]. Vehicle & pedestrian weights[5, 6].
96
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 49
Effects of Vertical Height Change[5]
S
H
2
H2 g SV
1
µ
Where:
µ = Ped friction valueS = Total throw distanceg = Gravitational accelerationH = Height of C/M
97
Effects of Vertical Height Change
H = 25 ft
2
H2 g SV
1
Where:
µ = 0.66S = 100 ftg = 32.2 f/s/sH = 25 ft
3ftV 53.86 fps 36.7mph
25ftV 49.71fps 33.8mph
No HV 54.41fps 37.1mph
θ
θ
98
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 50
Effects of Roadway Slope[5] (Downhill)
S
α
2
1Cos2 g SV
n
1
Si
µ
Where:
µ = Ped friction valueα = Roadway slope (degrees)S = Total throw distanceg = Gravitational acceleration
Degrees = Tan-1 Slope (%)
99
Effects of Roadway Slope[5] (Uphill)
S
α
2
1Cos2 g SV
n
1
Si
µ
Where:
µ = Ped friction valueα = Roadway slope (degrees)S = Total throw distanceg = Gravitational acceleration
Degrees = Tan-1 Slope (%)
100
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 51
Effects of Roadway Slope
No Slope: 37.1 mph (59.7 km/h) Uphill results: 38.5 mph (61.9 km/h) Downhill results: 35.5 mph (57.1 km/h)
2
1Cos2 g SV
n
1
Si
Where:
µ = 0.66α = ± 3 degreesS = 100 ft (30.48 m)g = 32.2 fps2 (9.81 m/s2)
[Difference: +1.4 mph (+2.2 km/h) & -1.6 mph (-2.6 km/h)]
101
Effects of Veh & Ped Weight[6]
No Weights: 37.1 mph (59.7 km/h) One Pedestrian: 38.6 mph (62.1 km/h) Two Pedestrians: 40.4 mph (65 km/h)
2M m s
1M2 gV
Where:
µ = 0.66M = 4200 lb (1909 kg)m = 175 lb (79.5 kg)s = 100 ft (30.48 m)g = 32.2 fps2 (9.81 m/s2)
(Two Peds)m = 175 lb (79.5 kg)m = 200 lb 90.9 kg)
[Difference: +3.3 mph (+5.3 km/h)]102
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 52
Effects of All Considerations [6]
Searle Minimum : 37.1 mph (59.7 km/h)
Carry Distance: 36.3 mph (58.5 km/h)
Weight: 38.6 mph (62.2 km/h)
Height, Weight: 38.2 mph (61.5 km/h)
Height, Weight, Slope: 37.2 mph (59.9 km/h)
All Considerations: 36.4 mph (58.6 km/h)
[Difference: +1.5 mph (+2.5 km/h) to – 0.7 mph (-1.2 km/h)]
2
1M
2 g SV
1
Cos Sim
d
M
n H
Where:
µ = 0.66M = 4200 lb (1909 kg)m = 175 lb (79.5 kg)α = - 2 degreesS = 100 ft (30.48 m)d = 4 ft (1.22 m)H = 3 ft (0.91 m)g = 32.2 fps2 (9.81 m/s2)
103
Controlled Crash Test Data[1]
Let us consider the following situation: Impact Speed (Vericom): 28.17 mph (45.32 km/h) Pedestrian Throw D: 44.33 ft (13.51 m) Pedestrian Airborne D: 25.53 ft (7.78 m) Pedestrian Sliding D: 18.8 ft (5.73 m) Pedestrian Friction Value: 0.66 Pedestrian Carry D: 2.62 ft (0.80 m) Pedestrian Takeoff θ: 8 degrees
How much of a difference does it make?
104
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 53
Controlled Crash Test Data[1, 11]
◦ Searle Min Only: 24.7 mph (39.7 km/h) (87%)
◦ Searle Min @ Takeoff θ: 27.35 mph (44 km/h) (97%)
◦ Searle Min @ Carry: 23.96 mph (38.55 km/h)(85%)
◦ Searle Min @ H (3.33 ft): 24.08 mph (38.74 km/h)(85%)
◦ Searle Min @ H (10 ft): 22.79 mph (36.67 km/h)(81%)
◦ Searle Min @ - 2o Slope: 24.03 mph (38.66 km/h)(85%)
◦ Searle Min @ +2o Slope: 25.3 mph (40.27 km/h) (89%)
◦ Searle Min @ Weights: 25.0 mph (40.22 km/h) (88%)
◦ Searle Min @ All (- 2o): 22.96 mph (36.94 km/h)(81%)
◦ Searle Min @ All (+ 2o): 24.20 mph (38.93 km/h)(85%)
◦ Searle Min Mean Value: 24.43 mph (39.32 km/h)(86%)
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Controlled Crash Test Data◦ Pedestrian Sliding Analysis: Pedestrian Sliding D: 18.8 ft (5.73 m) Pedestrian Friction Value: 0.66 Pedestrian Sliding Result: 19.29 mph (31.03 km/h)
◦ Pedestrian Airborne Analysis: Pedestrian Horizontal D: 25.53 ft (7.78 m) Pedestrian Vertical D: 3.33 ft (1.01 m) Pedestrian Takeoff : 8 degrees Pedestrian Airborne Result: 26.76 mph (43.05 km/h)
[Difference: - 7.47 mph (12.02 km/h)]
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WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 54
Crash Result Comparisons[1, 11]
◦ Vehicle Impact Speed: 28.17 mph (45.32 km/h)
◦ Ped Sliding Speed: (93.6%) 26.37 mph (42.43 km/h) [From Sliding Distance: (68.4%) 19.29 mph (31.03 km/h)] [Horizontal Speed Loss: 7.08 mph (11.39 km/h)]
◦ Ped Airborne Speed: (94.9%) 26.76 mph (43.05 km/h)
◦ Searle Min Speed: (87.7%) 24.73 mph (39.79 km/h)
◦ Searle Min 8o Speed: (97.0%) 27.35 mph (44.28 km/h)
◦ Ped Sliding / Ped Airborne: 98.5 %
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Quick Field Analysis[6] (Bratten: SAE 890859)
Vehicle Impact Speed: 28.17 mph (45.32 km/h)
Searle Minimum Speed: 24.7 mph (39.74 km/h)
Ped Sliding + Loss Speed: 26.37 mph (42.43 km/h)
Bratten Formula Speed: 25.76 mph (41.45 km/h)
Where:
s = 44.33 ft (13.51 m)g = 32.2 fps2 (9.81 m/s2)V = ? fps ( ? m/s)
[Bratten vs. Impact Speed: – 2.41 mph (-3.87 km/h), or 91.4%]
37.78 fps 25.76 m hV s pg
Reference: The Physics of Throw Distance in Accident ReconstructionJohn A. Searle, Road Accident Analysis Service, UK, SAE 930659
11.51m / s 41.45 k hV s pg
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WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 55
Head Strike Locations[1]
Does the vehicle’s design effect where the pedestrian’s head will impact the vehicle?
Does the pedestrian’s height effect where the head will impact on the vehicle?
Can the head strike location be used to estimate the vehicle’s impact speed?
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Head Strike Locations
Ford Ford
25-30 mph
30-45 mph
45-60 mph60+ mph
110
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 56
Head Strike Locations
1978 Oldsmobile Cutlass : Vehicle Speed = 26.35 mph 111
Head Strike Locations
2002 Kia Rio : Vehicle Speed = 28.20 mph 112
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 57
Head Strike Locations
1993 Ford Van : Vehicle Speed = 18.09 mph 113
Head Strike Locations[1, 8]
High Front Vehicle at 30 mph (48 km/h)
114Virtual CRASH Graphic (www.vcrashusa.com)
Low Front Vehicle at 30 mph (48 km/h)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 58
Head Strike Locations[1, 8]
Vehicle at 30 mph (48 km/h)
115Virtual CRASH Graphic (www.vcrashusa.com)
Head Strike Locations
Head strike location depends on much more than just the vehicle’s speed.
Depends upon vehicle design, hood length, pedestrian height, hood height, etc.
So, speed alone is not the deciding factor of where a pedestrian’s head will first impact on the vehicle.
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WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 59
Drop Test Research Experiments
Pedestrian Drop Testing Data[1, 9]
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Drop test data:Mean: 7.08 mph / 11.39 km/hs.d. 0.78 mph / 1.26 km/h
Drop/Fall Data
d = ?
A pedestrian drops, or falls off the back of a moving vehicle.
You do not know the vehicle’s speed, you only know the pedestrian’s sliding distance.
What can we do?
S = ?
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H = ?
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 60
Drop/Fall Data
d = 28.28 ft
Determine the pedestrian’s sliding distance. Determine the pedestrian’s friction value. Using , find the pedestrian’s sliding
speed for that phase of the event.
S = ?
μ = 0.58
V 2 gd
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Drop/Fall Data
Vslide = 32.5 fps (22.16 mph)
The resulting speed provides for the pedestrian sliding phase only.
Determine the height from which the pedestrian fell, or is dropped.
S = ?
H = ?
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WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 61
Drop/Fall Data
Determine the vertical velocity (Vy) of the pedestrian upon striking on the road surface.
Then, let us determine the amount of horizontal speed loss ( Vloss) upon ground impact.
S = ?
H = 5.25 ft
2 2y oV v sin 2 g H
loss yV V
Vy = 18.387 fps
= 10.66 fps (7.27 mph)
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Drop/Fall Data
Vslide = 32.5 fps (22.16 mph)
This is what we know so far. Let’s determine the pedestrian drop/fall
time using:
S = ?
H = 5.25 ft t = ?dslide = 28.28 ft
Vloss = 10.66 fps (7.27 mph)
2Htg
μ = 0.58
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WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 62
Drop/Fall Data
Vslide = 32.5 fps (22.16 mph)
The drop/fall time is used to determine the horizontal airborne distance.
But, what horizontal velocity is used to determine the distance?
S = ?
H = 5.25 ft t = 0.571 secdslide = 28.28 ft
Vloss = 10.66 fps (7.27 mph)μ = 0.58dairborne = ?
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Drop/Fall Data
Vslide = 32.5 fps (22.16 mph)
Add Vslide and Vloss , then use the resulting total as your horizontal velocity to calculate horizontal airborne distance.
S = ?
H = 5.25 ft t = 0.571 sec
dslide = 28.28 ftVloss = 10.66 fps (7.27 mph)
μ = 0.58dairborne = Vx ∙ t
Vx = 43.16 fps (29.43 mph)
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WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 63
Drop/Fall Scenario
Vslide = 32.5 fps (22.16 mph)
The resulting pedestrian speed is 29.43 mph at the start of drop/fall.
The total travel distance then becomes 52.92 ft.
S = 29.43 mph (43.16 fps)
H = 5.25 ft t = 0.571 sec
dslide = 28.28 ftVloss = 10.66 fps (7.27 mph)
μ = 0.58dairborne = 24.64 ft
dtotal = 52.92 ft
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Drop/Fall Data Comparison[9]
Ped Slide Speed = 22.18 mph
Vert. Velocity/Landing = 18.38 fps
Horz. Speed Loss = 7.27 mph
Total Fall Time = 0.571 sec
Airborne Dist. = 24.64 ft
Start of Fall Speed = 29.43 mph
S = 31.7 mph
Ped Slide Speed = 22.18 mph
Horz. Speed Loss = 7.27 mph
Airborne Dist. = 26.55 ft
Radar Speed = 31.7 mph
From “Three” field measurements: μ = 0.58
dslide = 28.28 ftH
“Calculated From Test Data” “Determined From Test Data”
“Results are: -2.27 mph, or 92.8 % of Test Speed” 126
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 64
127
128
y = 0.8541xR² = 0.6454
0.000
10.000
20.000
30.000
40.000
50.000
60.000
0.00 10.00 20.00 30.00 40.00 50.00 60.00
Sea
rle
Min
imu
m S
pee
d (
MP
H)
Test Speed (MPH)
Searle Minimum Equation V. Test SpeedWraps
Searle Min Formula = Impact Speed Linear (Searle Min)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 65
Searle Minimum (Wraps)
n=126 Most of the time results are under
predicted on average by 85% Also speaks to projection efficiency Predicts Speed ± 10.93 mph with 95%
confidence
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130
y = 1.0096xR² = 0.4921
0.00
10.00
20.00
30.00
40.00
50.00
60.00
0.00 10.00 20.00 30.00 40.00 50.00 60.00
Sea
rle
Max
imu
m S
pee
d (
MP
H)
Test Speed (MPH)
Searle Maximum Equation V. Test SpeedWraps
Searle Max Formula = Test Speed Linear (Searle Max) Linear (Formula = Test Speed)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 66
Searle Max (Wraps)
n=126 Many times will over predict the vehicle’s
speed Projection Efficiency on average 101% Predicts Speed ± 13.25 mph with 95%
confidence
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y = 0.9015xR² = 0.7782
0.000
5.000
10.000
15.000
20.000
25.000
30.000
35.000
40.000
45.000
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
Sea
rle
Min
imu
m S
pee
d (
MP
H)
Test Speed (MPH)
Searle Minimum V. Test SpeedForward Projection
Searle Minimum Searle Minimum = Test Speed Linear (Searle Minimum)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 67
Searle Min - Forward Projection
n=8 Tendency to under predict Projection Efficiency on average 90% Predicts Speed ± 15.53 mph with 95%
confidence More tests required
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134
y = 1.0192xR² = 0.7707
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
Sp
eed
Max
imu
m S
pee
d (
MP
H)
Test Speed (MPH)
Searle Maximum Speed V. Test SpeedForward Projection
Searle Maximum Searle Maximum = Test Speed Linear (Searle Maximum) Linear (Searle Maximum = Test Speed)
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 68
Searle Max - Forward Projection
n=8 Can over predict by 1% Projection Efficiency on average 101% Predicts Speed ± 17.73 mph with 95%
confidence More tests required
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136
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 69
137
6.33
3.32
126
x
s
n
138
6.53
1.06
126
x
s
n
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 70
139
5.20
1.11
8
x
s
n
Statistical Conclusions
Wraps:◦ Searle Min most of the time under estimated
and gave 85% of the vehicle speed on average.◦ Searle Max may over estimate or under
estimate.(S ± 13.25 mph at 95% conf.)
140
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 71
Statistical Conclusions
Forward Projections:◦ Searle Min most of the time under estimated.
(S ± 15.53 mph at 95% conf.)◦ Searle Max may over estimate or under
estimate.(S ± 17.73 mph at 95% conf.)
141
Statistical Conclusions
Friction Values for Asphalt:◦ Uniform distribution◦ Average 0.61◦ (S ± 0.18 at 95% conf.)
142
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 72
Statistical Conclusions
Horizontal Speed Loss (Wraps):◦ Normal distribution◦ Average 6.53 mph◦ (S ± 2.12 mph at 95% conf.)
143
Statistical Conclusions
Horizontal Speed Loss (Forward Proj.):◦ Normal distribution◦ Average 5.20 mph◦ (S ± 2.22 mph at 95% conf.)
144
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 73
Statistical Conclusions
Pedestrian Slide vs. Searle Min:
◦ Pedestrian slide underestimates vehicle speed all the time.◦ On average gave 61% of the vehicle speed.◦ (S ± 13% at 95% conf.)
22 gSV 2 gd vs. V1
145
Crash Test Statistics
146
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 74
Sources1. Becker, T.L., Reade, M.W. (2008 to 2016) “Analysis of Controlled
Pedestrian/Cyclist Crash Testing Data.” IPTM-UNF Pedestrian/Bicycle Crash Investigation Courses.
2. Reade, M.W. (2011) “The Anatomy and Analysis of a Typical Pedestrian/Bicycle Crash Event.” Proceedings of the NATARI Annual Combined Conference, Harrisburg, Penn.
3. Becker, T., Reade, M., Scurlock, B. (2015) “Simulations of Pedestrian Impact Collisions with Virtual CRASH 3 and Comparisons with IPTM Staged Tests.” Cornell University Library, arXiv: 1512.00790.
4. Searle, J.A., Searle, A. (1983) “The Trajectories of Pedestrians, Motorcycles, Motorcyclists, etc., Following a Road Accident.” SAE Technical # 831622.
5. Searle, J.A. (1993) “The Physics of Throw Distance in Accident Reconstruction.” SAE Technical # 9306759.
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Sources6. Searle, J.A. (2009) “The Application of Throw Distance Formulae.” IPTM
Special Problems in Traffic Crash Reconstruction, Orlando, Florida.
7. Hague, D.J. (2001) “Calculation of Impact Speed from Pedestrian Slide Distance.” Metropolitan Laboratory Forensic Science Service, ITAI Conference.
8. Virtual CRASH 3 (2016) “Software for Accident Reconstruction.” Web Site: http://www.vcrashusa.com/ , North America and Caribbean Distributor, Newberry, Florida.
9. Reade, M.W. (2011) “CATAIR Atlantic Region Pedestrian Crash, Drop & Friction Testing.” Riverview, New Brunswick, Canada.
10. Sullenberger, G.A. (2014) “Pedestrian Impact on Low Friction Surface.”SAE Technical # 2014-01-0470.
11. PEDBIKE 2000 Plus “Pedestrian and Bicycle Speciality Software.” Web Site: http://www.frsi.ca/, Riverview, New Brunswick, Canada.
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WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 75
Conference Paper
149
New IPTM Book
150
WREX 2016 Pedestrian Conference Presentation
May 2 - 6, 2016
By Mike W. Reade, CD 76
Conference Materials
151
The materials related to this presentation may be downloaded from the following web site.
http://www.frsi.ca/ ◦ Go to: (WREX2016 Page)
◦ Conference Paper
◦ Presentation PowerPoint (PDF)
◦ Presentation Videos
◦ Some Source Papers
Summary
There are several effects that need be considered in your analysis.
Knowing how they effect your final results is important.
Thank you.
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Graphic by: Virtual CRASH