A Plan to Drastically Reduce Truck Roll Overs

Transcription

1 A Plan to Drastically Reduce Truck Roll Overs File name: ALC 18Aug16 Truck Roll Over.pdf Same driver, same truck, same load, same corner 57 safe journeys, one disaster, WHY? Mike Robertson Phone

2 Today s Agenda! The Rollover Problem! HOW do Trucks Roll Over?! WHY - The Key Factors! A 3 Level Solution! Electronic Roll Stability! Minimum Static Rollover Threshold Carrington Roundabout Newcastle: NOTE the prime mover is on its ROOF, not its side, in a 60 kph zone The driver was doing 40km/hr.! Limits to CoG Height! Your Feedback Will this Work? 2

3 The Rollover Problem! About 350 truck Rollovers per annum in Australia! About 15 fatalities per annum in Rollovers! Most rollovers will involve some injury to the driver! The laws to control this risk simply say: You must load and drive the vehicle so as to remain stable (or words to this effect)! Without a definition of stable, its meaningless! 3

4 HOW do articulated trucks typically Roll Over?! The loaded trailer has a much higher Centre of Gravity than the prime mover. So it starts to roll first.! The chassis beams then twist, storing a large amount of energy.! Then the prime mover starts to lift and tilt up.! Once past the point of no return, (in mid air), the chassis untwists which typically flips the prime mover onto its roof. Often fatal for a driver without a seat belt?! Sometimes the side of the prime mover will not even get a scratch, as it doesn t touch the ground. 4

5 Film Clip from American Testing Particularly note in this video how the chassis twists as the rear axle group lifts off while the prime mover is still in full contact with the road. 5

6 Look Carefully at the picture... NO brakelights! 6

7 Analysis of load restraint test Driver does NOT know the trailer is going Already past the point of no return 7

8 Analysis of load restraint test Driver now knows, brake lights on 1.0 sec elapsed time, rims being scrubbed 8

9 Analysis of load restraint test Driver now feels it, catastrophic failure 2 sec elapsed time, cabin whipped over 9

10 The Key Factors Speed & Cornering! A BIG factor, but rarely the only one! Commonly used to blame the driver Freeway exit Hume highway Just a little too much speed and NOTE the prime mover is on its side, not its roof. Just a couple of k's over! ANY corner can be taken without truck roll over BUT reduced speed may be necessary, (<< speed limit!)! Corners which go from fast to slow speed zones and where the radius tightens unexpectedly are commonly involved (I.e. human error in reading the corner) 10

11 Speed + Turning = Centrifugal force The Overturning Force = Speed 2 Radius of Cornering If the Recommended speed was 60 km/h Is it serious if the truck does 65 km/hr Or if the truck does say 70 km/hr Speed Increases overturning by 17.4% 36.1% Now say the driver misjudges the line of the corner a little, and has to tighten up If the Recommended speed was 60 km/h Is it serious if the truck does 65 km/hr Or if the truck does say 70 km/hr Radius 90% Radius 80% % 46.7% % 70.1%

12 The Swerve factor 12

13 The Key Factors C of G. - Simple Rule of Thumb (Imperfect but useful!)! Calculate the Centre of Gravity of the payload (rack + product)! If OVER 2600 mm ABOVE ground = DANGEROUS = STOP!! If under 2300 mm above ground = Probably OK for normal trailers Say 1600 Typ t 7t Still~ Typ t 4t 7t Load 40 ft Shipping Flat Rack Trailer CoG height = Mass Green x height green + Mass gold x height gold divided by mass (green +gold) Typical CoG of a load of pipe & tube = = 2250 mm = fine Typical CoG of export load = mm = Danger! 13

14 The Other Factors! Load shift (due to Poor Load Restraint)! Load shift (Dynamic Slosh)! Poor Road geometry (Roundabouts & S curves) Unlucky Camry Lucky Camry! Suspension Type (air bags vs steel springs)! Tyres (dual or singles, low pressure etc.) Liverpool Sydney 2012, Cause = load shifted inside the container = fatality COR Charges = Guilty for consignor, carrier and driver not even charged 14

15 The Proposed 3 Stage Solution Define Stable in Law as being: 1. A vehicle fitted with Electronic Rollover Protection (on both truck and trailer), OR 2. A vehicle loaded such that it has a certified Static Rollover Threshold (SRT) of a minimum of 0.35g (or 0.40g if DGs), OR 3. A vehicle loaded to a table provided by the NHVR (devised by engineers to give an SRT of > 0.35g) 15

16 Level 1 Electronic Roll Over Programs! ERP will prevent the majority of truck rollovers (~80% reduction)! ERP is unlikely to help for severe swerve (such a startled awake response from a micro sleep)! Aust Trucking Assoc has called for mandatory ERP.! NSW EPA is mandating ERP from 2019 for all DGs! Retrofitting is not a sensible option (unless already with an Electronic Braking system)! The Problem? Aust trailers have an average age of ~14 years, so it will take a long time to make a difference. 16

17 Level 2 Calculate Your Own SRT! Compliance Option 2 would be for Operators to have an engineer calculate their actual SRT for their particular loading.! SRT > 0.35g is an existing requirement of Performance Based Standards trucks! Only a small number would be likely to take this option, but it would cater for PBS vehicles 17

18 Level 3 Follow the tables! Compliance Option 3 would be a prescription approach with limits to the allowable height of the centre of gravity of the payload! Follow the CoG Table! Tables would be prepared for generic situations eg:! Tri-axle semi with air bag suspension and dual tyres! Most existing loads would already comply.! Stock crates and hay loads would likely be an issue (they also rollover regularly!!) 18

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