Case Studies Using EDR Information

Richard Ruth, P.E.

Ruth Consulting, LLC

EDR Case StudiesPresented by Richard R. Ruth, P.E. Tundra tears Continental in Half

Copyright Ruth 2018 1

2007 Toyota Tundra Case Study –Key Learnings

• This case study illustrates that Toyota Gen 1 EDR’s (00/02) cannot display speeds over 126 kph , but that we can use engine RPM to calculate speed instead.

• RPM is proportional to speed in manual transmissions not in a shift, and for auto transmissions with lockup torque converter clutches when the clutch is locked. This case adds a complication that the due to the optional trailer tow package, the torque converter will not lock until 5th or 6th gear, and an allowance for torque converter slip had to be added in 4th gear.

• 02 EDR Data Limitations tell us that after the frontal airbag deploys and the freeze signal is on, it will not record any later events.

Conti

Tundra

Stop

Tundra

Cont

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Case Study – 07 Tundra tears Continental in half

• 07 Tundra driver drunk, on through st. with 30mph/50kph speed limit.

• 00 Lincoln continental on side street turns toward Tundra from side street 4

• Impact Tundra LF to Conti driver B pillar, tears Conti in half, fuel dumps and ignites

• Tundra rolls onto side, slides 75m to rest

• 3 in Conti severely injured

Lincoln Continental Torn in Half, rest near impact

Continental back end nearly torn off , fuel fire

Tundra slides rear end first to 75M from crash

SLIDE

AFTER FREEZE SIGNAL HAS BEEN TURNED ON, SUBSEQUENT EVENTS WILL NOT BE RECORDED

RPM ROUNDED DOWN TO LOWER 400

MAX VEHICLE SPEED DISPLAYED 78.3 MPH

TRIGGER 1 NOT RELATED

NO PRECRASH DATA

Something on seat

GEN 1&2 MAX IS BIGGEST # ON PAGE

Research Transmission Gear Ratios

WIKIPEDIA COMES THRU!!! 5.7L 4x4 TRANS

Input Data in Speed in Gear Calculator Spreadsheet

Speed Calculated from Engine RPMMinimum Speed

𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 = (4400𝑟𝑟𝑟𝑟𝑟𝑟 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 10% 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑙𝑙𝑟𝑟𝑐𝑐𝑙𝑙𝑟𝑟 𝑙𝑙𝑙𝑙𝑠𝑠𝑟𝑟)∗60𝑟𝑟𝑠𝑠𝑐𝑐/ℎ𝑟𝑟1.00 𝑐𝑐𝑟𝑟𝑡𝑡𝑐𝑐𝑙𝑙 4𝑐𝑐ℎ 𝑔𝑔𝑙𝑙𝑡𝑡𝑟𝑟∗4.30 𝑡𝑡𝑎𝑎𝑙𝑙𝑙𝑙∗649 𝑟𝑟𝑙𝑙𝑐𝑐𝑙𝑙/𝑟𝑟𝑠𝑠𝑙𝑙𝑙𝑙

= 85.2 mph

Maximum Speed

𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 = (4800𝑟𝑟𝑟𝑟𝑟𝑟 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 10% 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑙𝑙𝑟𝑟𝑐𝑐𝑙𝑙𝑟𝑟 𝑙𝑙𝑙𝑙𝑠𝑠𝑟𝑟)∗60𝑟𝑟𝑠𝑠𝑐𝑐/ℎ𝑟𝑟1.00 𝑐𝑐𝑟𝑟𝑡𝑡𝑐𝑐𝑙𝑙 4𝑐𝑐ℎ 𝑔𝑔𝑙𝑙𝑡𝑡𝑟𝑟∗4.30 𝑡𝑡𝑎𝑎𝑙𝑙𝑙𝑙∗649 𝑟𝑟𝑙𝑙𝑐𝑐𝑙𝑙/𝑟𝑟𝑠𝑠𝑙𝑙𝑙𝑙

= 92.9 mph

Speed Calculated from RPM for Each GearFor Min 4400 to Max 4799 RPM when 4400.Tundra MUST be in 4th GearRPM 1st Gear 2nd Gear 3rd Gear 4th Gear 5th Gear 6th Gear4400 25.56 43.46 62.96 85.18 130.01 160.974799 27.88 47.40 68.67 92.91 141.80 175.56

Calculate Time Distance to Locate EDR Points on Google Earth Phot

• Last 0.4 sec * 72.1 mph * 1.466 ft/sec = 42.3 ft (12.9m) • Next 1.0 sec * 78.3+ mph*1.466 = 114.8 ft (35.0m) + 42.3 = 157.1 (47.9)• Next 1.0 sec * 78.3+ mph*1.466 = 114.8 ft (35.0m) + 157.1 = 271.9 (82.9)• Next 1.0 sec * 78.3+ mph*1.466 = 114.8 ft (35.0m) + 271.9 = 386.7 (117.9)• Next 1.0 sec * 78.3+ mph*1.466 = 114.8 ft (35.0m) + 386.7 = 501.5 (152.9)

Recap of Learnings so far

Per RPM, 85.2-92.9, Per Accelerator, Increasing

Per brake, Slowing

Speed at Impact from Last Precrash Speed Data Sample

MIN MaxLast reported speed 72.1 72.1 mphChange since last data -7.3 0.0 ABS Wheel Slip +5% 0.0 +3.6 +/-4% accuracy U -2.9U +U2.9SPEED AT IMPACT 61.9 78.6 mph

(center of range 70.3)

Per RPM, 85.2-92.9, Per Accelerator, Increasing

Per brake, Slowing

Speed at Impact combining EDR + Scene DataPost Crash Travel was 246 ft• 𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷 𝑪𝑪𝑪𝑪𝑪𝑪𝑷𝑷𝑪𝑪 𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺 𝑺𝑺𝑺𝑺 = 𝑺𝑺𝟑𝟑 ∗ 𝟐𝟐𝟐𝟐𝟐𝟐 ∗ 𝟑𝟑.𝟐𝟐 = 𝟓𝟓𝟐𝟐.𝑺𝑺𝟑𝟑𝑺𝑺𝑪𝑪 nominal• 𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷 𝑪𝑪𝑪𝑪𝑪𝑪𝑷𝑷𝑪𝑪 𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺 𝑺𝑺𝑺𝑺 = 𝑺𝑺𝟑𝟑 ∗ 𝟐𝟐𝟐𝟐𝟐𝟐 ∗ 𝟑𝟑.𝑺𝑺 = 𝟐𝟐𝟒𝟒.𝟑𝟑𝟑𝟑𝑺𝑺𝑪𝑪 min• 𝑷𝑷𝑷𝑷𝑷𝑷𝑷𝑷 𝑪𝑪𝑪𝑪𝑪𝑪𝑷𝑷𝑪𝑪 𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑷𝑷 𝑺𝑺𝑺𝑺 = 𝑺𝑺𝟑𝟑 ∗ 𝟐𝟐𝟐𝟐𝟐𝟐 ∗ 𝟑𝟑.𝟓𝟓 = 𝟐𝟐𝟑𝟑.𝟒𝟒𝟑𝟑𝑺𝑺𝑪𝑪𝐦𝐦𝐦𝐦𝐦𝐦Combining the post crash speed with the Delta V • 𝐒𝐒𝐒𝐒𝐒𝐒𝐒𝐒𝐒𝐒 𝐦𝐦𝐚𝐚 𝐈𝐈𝐦𝐦𝐒𝐒𝐦𝐦𝐈𝐈𝐚𝐚 𝐒𝐒𝐒𝐒 = 𝐏𝐏𝐏𝐏𝐏𝐏𝐚𝐚 𝐈𝐈𝐦𝐦𝐒𝐒𝐦𝐦𝐈𝐈𝐚𝐚 𝐒𝐒𝐒𝐒𝐒𝐒𝐒𝐒𝐒𝐒 𝐒𝐒𝑺𝑺 −𝐂𝐂𝐂𝐂𝐦𝐦𝐂𝐂𝐂𝐂𝐒𝐒 𝐢𝐢𝐂𝐂 𝐕𝐕𝐒𝐒𝐕𝐕𝐏𝐏𝐈𝐈𝐢𝐢𝐚𝐚𝐕𝐕 𝚫𝚫𝐕𝐕𝐦𝐦

• 𝑺𝑺𝐒𝐒 = 𝟓𝟓𝟐𝟐.𝑺𝑺𝟑𝟑𝑺𝑺𝑪𝑪 − −𝐒𝐒𝟒𝟒.𝟗𝟗𝟑𝟑𝑺𝑺𝑪𝑪 = 𝟒𝟒𝟐𝟐.𝟐𝟐𝟑𝟑𝑺𝑺𝑪𝑪 𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵𝑵• Taking into account the +/-10% accuracy of Delta V data and the range on

the drag factor• 𝑺𝑺𝐒𝐒 = 𝟐𝟐𝟒𝟒.𝟑𝟑𝟑𝟑𝑺𝑺𝑪𝑪 − −𝐒𝐒𝟐𝟐.𝐒𝐒 = 𝟐𝟐𝑺𝑺.𝐒𝐒𝟑𝟑𝑺𝑺𝑪𝑪𝑵𝑵𝑴𝑴𝑴𝑴𝑴𝑴𝟑𝟑𝑴𝑴𝟑𝟑• 𝑺𝑺𝐒𝐒 = 𝟐𝟐𝟑𝟑.𝟒𝟒𝟑𝟑𝑺𝑺𝑪𝑪 − −𝐒𝐒𝟗𝟗.𝟒𝟒 = 𝟖𝟖𝟑𝟑.𝟐𝟐𝟑𝟑𝑺𝑺𝑪𝑪𝑵𝑵𝑪𝑪𝑴𝑴𝑴𝑴𝟑𝟑𝑴𝑴𝟑𝟑

Speed at Impact from Inline Momentum• M1V1 + M2V2 = M1V3 + M2V4 Rearrange to V1 =(M1V3 + M2V4 – M2V2)/M1• M1 = Tundra Weight = 5680 curb + 150 driver = 5830 lbs• M2 = Continental Weight = 3868 curb + 450 allowance for 3 occupants = 4318 lbs• V2 = Continental speed in direction toward Tundra = 10mph (+/-2) * sin 45 = 7 mph (+/- 1.4 mph)• V3 = Tundra departure speed = 54.3mph (range 47.1 to 60.7)• The Continental Delta V is DV2=DV1*(W1/W2) = 17.9*(5830/4318) = 24.2 mph (+/-10% or +/- 2.4

mph)• V4 =Continental postcrash speed = precrash speed 7 mph - Delta V 24.2 = 17.2 mph +/-3.8 mph• (this is also consistent with the post crash travel of the Continental)

• V1 = (5830*54.3 + 4318*17.2+4318*7)/5830 = 72.2 mph • V1 = (5830*47.1 + 4318*15.2+4318*5)/5830 = 61.2 min• V1 = (5830*60.7 + 4318*19.2+4318*9)/5830 = 82.5 max

Compare Speed at Impact Calculations |------speed at impact from Delta V & postcrash travel-----|

63.1 72.2 80.4

|---------------speed from last 72.1 mph speed data-------------|

61.9 70.3 78.6

|-------------------speed from inline momentum analysis ---------------------|

61.2 72.2 82.5

|---------------overlap between methods----------------|

63.1 70.8 78.6

Could he stop?

• Stop distance at 85 mph = 𝑆𝑆2

30𝑓𝑓= 852

30(0.7)=344ft

• Stop distance at 30 mph = 𝑆𝑆2

30𝑓𝑓= 302

30(0.7)=43 ft

• 344/43 = 8 times longer to stop at 85 mph than speed limit• Driver applied brakes at -1.4 sec, too late to stop

(about 170 ft to impact)

• TRIAL RESULT: Guilty Verdict on 3 counts of inflicting serious injury while DUI and reckless