Mansfield

Mansfield (pronounced manz-feeld)

The slang term for the protective metal structures attached to the underside of trucks and trailers, designed to protect occupants of vehicles in “under-run” crashes (the victim’s vehicle impacting, often at mid-windscreen height with the solid frame of the truck’s tray).  A Mansfield bar, technically is called the RUPS (Rear Underrun Protection System).

1967: The devices are known as “Mansfield” bars because interest in the system was heightened after the death of the actress Jayne Mansfield (1933-1967), killed in an under-run accident on 28 June 1967.  The origin of the surname Mansfield is habitational with origins in Mansfield, Nottinghamshire. The early formations, recorded in the thirteenth century Domesday Book, show the first element uniformly as the Celtic Mam- (mother or breast (Manchester had a similar linkage)) with the later addition of the Old English feld (pasture, open country, field) as the second element.  The locational sense is thus suggestive of an association of the field by a hill called “Man”.  The etymology, one suspects, would have pleased Jayne Mansfield.

Mansfield crash aftermath, 28 June 1967.

On 28 June 1967, Jayne Mansfield was a front-seat passenger in a 1966 Buick Electra 225, en route to New Orleans where she was next day to be the subject of an interview.  While cruising along the highway at around two in the morning, the driver failed to perceive the semi-truck in front had slowed to a crawl because an anti-mosquito truck ahead was conducting fogging and blocking the lane.  The mist from the spray masked the truck's trailer and, the driver unable to react in time, the car hit at high speed, sliding under the semi-trailer, killing instantly the three front-seat occupants.  Although the myth has long circulated she was decapitated, an idea lent some credence by the visual ambiguity of photographs published at the time, while it was a severe head trauma, an autopsy determined the immediate cause of death was a "crushed skull with avulsion of cranium and brain".

Mansfield crash aftermath, 28 June 1967.

The phenomenon of the “under-run” accident happens with some frequency because of a co-incidence of dimensions in the machines using the roads.  Pre-dating motorised transport, loading docks were built at a height of around four feet (48 inches; 1.2 m) because that was the most convenient height for men of average height engaged in loading and unloading goods.  Horse-drawn carts and later trucks were built to conform to this standard so trays would always closely align with dock.  Probably very shortly after cars and trucks began sharing roads, they started crashing into each other and, despite impact speeds and traffic volumes being relatively low, the under-run accident was noted in statistics as a particular type as early as 1927.

In the post-war years, speeds and traffic volumes rose and, coincidentally, the bonnet or hood-lines on cars became lower, the windscreen now often somewhere around four feet high so the under-run vulnerability was exacerbated, cars now almost designed to slide under a truck to the point of the windscreen, thus turning the tray into a kind of horizontal guillotine, slicing into the passenger compartment at head-height.  That’s exactly how Jayne Mansfield died.

Rear under-run Mansfield bar.

The US authorities did react, federal regulations requiring trucks and trailers be built with under-ride guards (reflectorized metal bars hanging beneath the back-end of trailers) passed in 1953, but the standards were rudimentary and until the incident in 1967, little attention was paid despite similar accidents killing hundreds each year.  The statistics probably tended to get lost in the ever-increasing road toll, cars of the era being death traps, seat belts and engineering to improve crashworthiness almost unknown.

The Mansfield bar works by preventing the node of the car sling under the truck, protecting the passenger compartment from impact.

After 1967, although regulations were tightened and enforcement, though patchy, became more rigorous, deaths continued and in the US there are still an average of two-hundred fatalities annually in crashes involving Mansfield Bars.  There are proposals by the Federal Motor Carrier Safety Administration (FMCSA) to include Mansfield Bars on any truck inspection and suggesting to improve the design to something more effective, the devices since 1963 little more than brute force impact barriers and there’s interest in spring-loaded devices which would absorb more of the energy generated in a crash.  Coincidentally, the increasing preference by consumers for higher, bluff-fronted SUVs and light (a relative term in the US market) trucks has helped improve this aspect or road safety.

There’s concern too about side impacts.  Only a very small numbers of trucks have ever been fitted with any side impact protection and this omission also make corner impacts especially dangerous.  The cost of retro-fitting side (and therefore corner) Mansfield bars to a country’s entire heavy transport fleet would be onerous and it may be practical to phase in any mandatory requirements only over decades.

A photograph of a parked car & truck, the juxtaposition illustrating the limits of the protection afforded, especially in cases when the truck's tray extends beyond the rear axle-line.  The moving truck was one of two hired by Lindsay Lohan when in early 2012 she moved out of 419 Venice Way, Venice Beach, Los Angeles where during 2011 she lived (in the house to the right; the semi-mirrored construction sometimes called a “pigeon pair”) next door to former special friend Samantha Ronson who inhabited the one to the left (417).  She was compelled to move after a “freemason stalker threatened to kill her”.

Sofia Loren (b 1934) and Jayne Mansfield, Los Angeles, 1957.