Safety plays a vital role in vehicle design and construction. To keep the risk of vehicle accident as low as possible vehicles are designed with technical feasible system and components. Also the vehicles are designed in such a way that the driver of the vehicle feels the optimum comfort which enables him to enhance the performance capabilities.
Active safety is further subdivided as follows:
1.Driving Safety : For safe and easy drivability the vehicles are designed in such a way that the Brakes, wheel control, Tyres, suspension and steering matched to each other as much as possible so that the vehicle can be easy to drive with safe even in poor road conditions. In order to achieve the high level of Active safety in modern commercial vehicles the systems like ABS, ASR, Electronic Brake system (EBS) in conjunction with Electronic Stability Programme ESP are incorporated in the vehicle design.
2.Fitness Related Safety: The Cabin occupants including the driver are exposed to various physical loads like Vibrations, noises, and other climatic influences. The lower these physical loads more comfort situations for the driver which enhances his performance capabilities.
3.Perception related Safety: This involves detection of all events and signals around the vehicles by means of :
a)Adequate lighting equipments.
b)Acoustic warning equipments and
c)Views through rear and side view mirrors.
In order achieve perception related safety, the modern commercial vehicles are equipped with Sensor detection units. These sensor detection units are correspondingly designed electronic systems evaluates the sensor signals and feeds the information to the driver so as to improve the traffic perceptions. Also the following systems enhances the perception related safety.
1. Lane Guard System (LGS): Which detects the course of Traffic lanes.
2. A radar sensor runs long range scans in front of the vehicle for the Distance Controlled Cruise control.
In the Implementation Stage
Distance cruise control short range (Stop and Go)
Monitoring the side area opposite to the driver (Turn Assistant): Which indicates the driver for any substance in the side area when taking turn.
4.Operating Safety: Not to distract driver’s attention, all operating elements are arranged and kept within the reach of the driver.
Passive safety mainly depends on external factors, and which is intended to minimise the consequences of the Accidents. The Passive is classified as Exterior Safety and Interior Safety.
Exterior Safety deals with safety parameters in order to reduce the damage to the outside persons/ properties by incorporating following two major design factors in the vehicle namely Exterior Shape of the Body and
Deformation characteristics of the body.
In the event of Accidents involving two vehicles the occupants of the lighter vehicle are exposed to more danger than the occupants of the stronger vehicle. The commercial vehicles are designed in such a way that the impact forcer of the accident travels in longitudinal directions. And the body height also kept as low as possible to minimise damages to the passenger car which involves in the accident. Also the design of front under ride protection prevents the opposite vehicle from overturning in the event of crash.
The Deformation characteristic of the truck plays a vital role in the event of accidents or crash. Which absorbs the partial energy exerted by the impact and safe guards the occupants and the internal elements of the vehicle.
The prescribed height of the rear under ride protection for trucks and trailers is 550 mm between upper edge of the road surface and the vehicle frame in the unladed condition. Since the under ride protection can not be maintained in most of the commercial vehicles due to variable applications it is designed in such a way that the height can be adjusted and provided with shape of a pipe.
*Side protection devices are incorporated on both side of the vehicles with wide profiles made of steel or Aluminum as protection devices.
Retention system involves prevention of driver or passenger from moving from his seating position in case of collision. This can prevents the occupant’s impact with the windows or other internal structure of the vehicle. There are two commonly used retention system in commercial vehicles : Seat belt System and Air Bag system.
The seat belt system combined with the air bag system gives optimum safty o the driver and the occupants.
In order to achieve the maximum safety the automatic three point seat belt system become standard equipment in all commercial vehicles. This system is integrated with the driver’s seat and it is independent of the horizontal or vertical movement of the driver’s seat. The spring tensioner in the seat belt brings the belt closer to the body when the belt unrolls during the impact. During sudden brake a lock engages and the seat belt holds the body of the driver firmly on its seat. With the help of belt force limiter some slackening of the locking reel achieved and ensures the person wearing the seat belt does not suffer any internal injury.