It comes to the c

No two ac­ci­dents are alike, so crash rat­ing com­par­isons can be hit or miss

Herald Sun - Motoring - - Cover Story -

test can pos­si­bly hope to pre­dict the safety of any given ve­hi­cle for all pos­si­ble sce­nar­ios,’’ Malk­outzis says.

Thus, it is crit­i­cal that we have a range of data sourced through dif­fer­ent method­olo­gies to in­form im­prove­ments to our ve­hi­cle de­sign and engi­neer­ing, and to help cus­tomers choose the ve­hi­cle most suit­able to their pur­pose.’’ On that ba­sis,

looks at the strengths— and weak­nesses — of the re­spec­tive safety rat­ings. MUARC Monash’s an­nual Used Car Safety Rat­ings re­flect physics and rep­re­sent ve­hi­cle safety in the real world. Big­ger cars are safer than smaller cars; newer ve­hi­cles are safer than old ones.

But the data­base of more than 5 mil­lion po­lice-re­ported crashes fo­cuses on driver safety rather than that of all oc­cu­pants and is then

weighted’’ for vari­ables such as driver age and gen­der. The re­port also notes: Rat­ings are not es­ti­mated for ve­hi­cle mod­els where there are less than 20 injured driv­ers and/or less than 100 in­volved driv­ers in the Aus­tralasian crash data, as the re­sult­ing rat­ings es­ti­mates from smaller quan­ti­ties of data than this are con­sid­ered too sta­tis­ti­cally un­re­li­able’’.

The other is­sue is so­cial engi­neer­ing— an in­her­ent com­po­nent of the Monash re­sults. The re­port gives the pre­vi­ously pro­vided out­right

crash­wor­thi­ness’’ rat­ing of the ve­hi­cle along­side a rat­ing of its ag­gres­siv­ity’’ in term of in­jury to other road users.

UCSR re­sults now com­bine those two rat­ings when de­ter­min­ing the safe pick’’ ve­hi­cles. It’s a laud­able sen­ti­ment but it’s also a pol­icy that re­stricts in­formed choice — most peo­ple buy­ing a car would pre­fer to know both fac­tors, sim­ply on the ba­sis that for any two safe pick’’ ve­hi­cles, one may be marginally bet­ter at pre­serv­ing the life of the car buyer while the other may be frac­tion­ally kinder to other par­ties. Guess which one I’d put my kids in.

As such, the re­port is as much about reg­u­lat­ing buy­ing be­hav­iour as it is about

ve­hi­cle safety.

ANCAP

The Aus­tralian New Car As­sess­ment Pro­gram sub­jects ve­hi­cles to an in­ter­na­tion­ally recog­nised set of crashes: frontal off­set, side im­pact, pole and pedes­trian— yet in many cases, the re­sults don’t equate to the UCSR re­sults. MUARC re­mod­elled the ANCAP data and found vari­ances of 55-65 per cent be­cause ANCAP pro­to­cols still do not re­flect all-im­por­tant real world crash con­fig­u­ra­tions and in­jury out­comes to key body re­gions’’.

One rea­son for this is ANCAP’s rat­ings are rel­a­tive to the class, not ab­so­lute. A five-star small car won’t pro­vide the same pro­tec­tion as a five-star large car. If ev­ery­thing else is equal, big­ger is bet­ter.

ANCAP notes: It is not ap­pro­pri­ate to com­pare rat­ings across ve­hi­cle cat­e­gories, par­tic­u­larly if there is a large weight dif­fer­ence. The rea­son is that in car-to-car crashes, the heav­ier ve­hi­cle has a the­o­ret­i­cal ad­van­tage (du the physics of the crash). Sim­i­larly, a higher ride h might be an ad­van­tage in to-car crash.

How­ever in sin­gle veh crashes, such as with soli ob­jects, the weight might longer be an ad­van­tage.’

See­ing stars: Side-im­pact test­ing for EuroNCAP

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