26.10.1997

Alfa 156: Safety


Introduction
In designing the Alfa 156, particular care was taken over its safety, starting with the preventive kind i.e. the complex of engineering features that help the driver to stay alert. Indeed that need was always on the design engineers' minds as they attended to aspects like comfort, engine noise, climate control, cockpit ergonomics, instrument location and legibility.

Active safety
Acceleration, road grip, braking. These have always been Alfa Romeo features. The Alfa 156 carries on that tradition, which it enriches with some technical innovations. Several features make the Alfa 156 a paragon of active safety: a braking system fitted with servo and additional chamber, plus ABS and electronic braking (EBD) and the suspension combination of double wishbones at the front and MacPherson struts at the rear.

Brakes
This adopts four big discs (ventilated at front on the 2.0 T. Spark, 2.4 JTD and 2.5 V6 24V) with brake servo and ABS as standard. This allows very short braking distances: just 39 metres at 100 km/h.
The Bosch 5.3 ABS system is the most advanced of its kind on the market. It adopts 4 active sensors and 4 channels and incorporates an EBD (Electronic Brake Distributor). These features guarantee:
- maximum braking on each wheel close to wheel lock;
- total vehicle control in rear-wheel-lock situations;
- extremely prompt response;
- the ability to adapt automatically to all braking conditions;
- reduced control-unit weight.
This is the first time Alfa Romeo has adopted active sensors. Like the traditional types, they measure wheel speed, but active sensors also process the signal themselves instead of transmitting it to the control unit. The advantages are:
- immediate response;
- the ability to recognise speeds close to zero (passive sensors do not 'read' speeds under 4 km/h);
- reduced sensitivity to disturbances caused by electromagnetic fields or the heating of the road surface used in some North European countries.
The active sensors' ability to identify very low speeds supplies valuable information about vehicle movements to the optional navigation system.
For its part, the EBD guarantees optimum distribution of braking power among the four wheels and adapts braking to wheel grip and brake pad efficiency conditions.

Passive safety
The Alfa 156 meets the safety standards to be imposed by upcoming EU regulations. Indeed it passed 70 crash tests, in addition to the tests (70 more) involving rams and computer simulations.
In the event of a collision, the car's occupants are protected by a crumple zone bodyshell, impact beams in the doors, containment systems like seat-belt pretensioners and airbags, and by the Alfa 156's Fire Prevention System.
Seat belts are fundamental to driver and passenger safety and the Alfa 156 adopts 3-point inertia reel belts on all seats. The front seat-belts come with electronic pretensioners which respond to impacts by taking up about 10 cm of seat-belt slack in just a few milliseconds, to ensure a snug fit on the wearer's body.
The front belts are anchored to the seat at two points. This offers better containment than a traditional floor-mount system, guaranteeing all front seat occupants the same level of protection whatever their size and shape and whatever their seat setting. Crash tests reveal that this system reduces impacts on the pelvic area by as much as 30%.
All head-restraints can be adjusted to the required height, the rear restraints being semi-recessed for combined rear visibility as well as safety. All 156 versions offer the option of a third rear head-restraint and seat-belt, the latter a standard inertia reel model and not just a simple lap belt.
The driver's airbag (42 litres) is standard. A front passenger bag is an optional extra and side airbags will become available from next May. The 42-litre driver's airbag is stored inside the steering wheel and is governed by an electronic control unit. It is activated by a sensor that measures vehicle deceleration, but only if the impact recorded is big enough to warrant airbag use (speeds above 20 km/h). So the airbag is not inflated if another car simply grazes the Alfa 156 or if the Alfa driver hits a kerb. The time lapse between initial impact and airbag activation is just 20 milliseconds and it takes a further 35 milliseconds to inflate the bag, which fills with completely non-toxic, inert Argon gas.
The optional front passenger airbag holds 90 litres. This system incorporates a sensor inserted into the seat frame that deactivates the mechanism if the front seat is unoccupied. The airbag can also be deactivated by a key set in a special switch at the end of the facia. This must be done if an infant is to be carried in a rear-facing child seat.
All the Alfa 156 airbags are made of nylon, a material which allows the bag to deflate rapidly after impact and limits the possibility of abrasion to the skin.

Side airbags
To protect front seat passengers when the side of the car is hit sharply, the Alfa 156 introduces side airbags that protect the chest, pelvis, and, to a certain extent, the head.
The Alfa 156 is the Group's first model to offer side airbags. They are housed in the front seat squabs, a solution which offers several advantages, particularly that of being able to fit smaller bags than would be necessary if the airbags were housed in the doors, with the same level of protection. And above all, they guarantee the best possible protection of occupants, regardless of their size, their position or the seat adjustment.
A seat-mounted side airbag opens with a movement that minimises the possible consequences of contact between the bag and the passenger, because it opens away from the occupant instead of towards him, as a door-mounted bag would.
The system is based on three components. The sensors, mounted on the centre pillars, receive a warning of excessive lateral acceleration caused by an impact and send it to the electronic control unit. This also receives the acceleration signal, compares it with the indications from the sensors and, when necessary, order the side airbags to open. The bags are made of nylon, with a volume of about 12 litres, and they inflate in 5-7 milliseconds.
The presence of the airbag in the seat squab is indicated by the cover to the compartment in which it is housed. This has a technical as well as a styling function, because it allows the airbag to inflate correctly, without tearing the seat upholstery.
The electronic control unit governing side airbag opening also controls operation of the front airbags and the seat-belt pre-tensioners, all these devices are governed together, to enhance progressive occupant protection. The system always gives a reply that reflects the severity of an impact: it does not intervene in the case of side impact at speeds below 15 km/h.

Fire Prevention System (FPS)
This system places Alfa Romeo in the fire-fighting vanguard. Its main components include:
- an inertia switch tripped in the event of a crash that takes only milliseconds to stop the fuel pump to prevent fuel leaks if fuel delivery lines are ruptured;
- an anti-flowback valve set downstream of the tank to prevent fuel leaking back into it in the event of a crash or if fuel lines are damaged;
- fuel tank made of extra-tough, fireproof plastic and stored in a protected place in front of the rear axle;
- heat shields (on petrol-engined versions) in the form of aluminium panels which isolate the catalyst and exhaust pipes as a precautionary measure against the overheating that can arise if a cylinder misfires;
- an electrical system equipped with special shields and maxifuses that cut off the power in the event of a fire;
- an engine bay whose layout is designed to minimise risk in crash situations and protected to stringent U.S. flame-proofing standards;
- the 1.8 and 2.0 T. Spark and the 2.5 V6 24V engines are fitted with a 'returnless' fuel feed system, in other words one without a return petrol line from the engine to the tank, because this function is incorporated in the petrol pump. This reduces the risk of fire after a collision.

Torsional and flexional rigidity
A stiff bodyshell makes a significant contribution to active and passive safety and to ride comfort. The Alfa 156 offers torsional rigidity of 110,000 kgm/rad., thereby significantly enhancing the car's stability and roadholding.
For passenger protection in the event of a crash, the bodyshell adopts:
- controlled-crumple longitudinals to reduce impact forces;
- impact beams inside the doors for extra protection against side-on collisions;
- reinforcements in the roof pillars, door hinges and other areas subject to particular stress in the event of violent impact;
- a bulkhead behind the rear seat back.
And for protection against rust, 65% of the sheet steel used is galvanised.

Protection against theft
Alfa CODE II immobiliser
The Alfa 156 is protected against attempted break-ins by an Alfa CODE II immobiliser, an uprated version of the well-known Alfa CODE. In some countries insurance companies offer lower premiums on cars equipped with this system, which immobilises the engine against any attempt to start the car without the owner's own car key. Inside the key head there is a transponder, a microchip that responds to interrogation by the electronic control unit when the ignition key is inserted, by delivering a secret four digit code that authorises the car to start.
Instead of having a single permanent code number, the second generation Alfa CODE adopts a new code for every car start. (In other words there is no master key to keep safe.) In addition the message in encrypted using a secret algorithm. The key transponder itself is programmed with over ten thousand billion possible combinations. A special control unit housed in a protected position is connected to a coil set inside the ignition switch that reads the code number. The control unit then compares the secret code number transmitted by the car key against the starter codes inside its own memory and then transmits another code with over a thousand billion possible combinations to the engine control unit which is then authorised to switch on the engine.
The system is provided with an emergency program to handle malfunctions. This is activated by a special code that is stored on the CODE card and known only to the car's owner.

Theft alarm
In addition to the Alfa Code immobiliser, Alfa Romeo will also supply an anti-theft alarm to protect the contents of the Alfa 156's cabin and boot. This system, with its perimeter and area sensors, is activated by remote control on a radio frequency that is built into the ignition key and also controls the central locking system.
Simple but effective solutions have been adopted to combat break-ins by preventing the car being opened from the outside. For example, shields to protect door and bonnet opening mechanisms and the door-lock button on the panel.


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