Here is a basic physics explanation for many of the improvements:
When you are in a car that is moving you have momentum = mass x velocity and kinetic energy = 1/2 x mass x velocity squared. When you stop such as in a crash you have to get rid of momentum and kinetic energy. Momentum is gotten rid of by the force of the crash exerted over time and energy is gotten rid of by the force of the crash exerted over a distance.
In the old days (before 1970's) car bodies were made of rigid materials. When a crash occurred the time and distance were short so the forces were high injuring the passengers. Without seat belts bodies are free to move and don't slow down with the car does leading to more injuries.
Fewer injuries occur if you are secure in the car and it takes more time to stop. Think jumping off of a wall. (Don't try this at home without supervision). If you keep your legs rigid the time is short and the forces on your bones are high. It hurts a lot! Bending your legs when you land increases the time to slow down and decreases the force. Air bags basically add stopping time which decreases the force on the humans. Break away poles and guard rails basically slow you down so you don't have as rigid a stop.
The kinetic energy is dissipated by breaking things. If the car is rigid it will be dissipated by breaking you the passenger. Making the front end of the car less rigid allows the energy to crush it instead of you. Front car frames crush more easily in crashes but the passenger frames are more rigid to keep you secure.
Road safety has tremendously increased over the last several decades. In cars, road safety includes emissions restrictions, daytime running lights, air bags, and antilock brake systems. In road safety, the roads are constructed a little better from materials, less potholes and more repairs to eliminate vehicle damage and loss of control. The guard rails and concrete dividers have also been implemented more, especially on interstates. Traffic lights and caution lights have also been implemented more by using surveying equipment to determine what roads and intersections could best benefit from these tools.
1. good restraint system including seatbelts and air bag
2. side impact tested.
3. good braking.
4. good handling.
5. good acceleration
1. visible signs.
2. speed limits.
3. good lights especially at night.
Over the centuries as a consequence of rapid industrialization and scientific and technological development the science of laying roads has made great progress. The scientific and technological developments in laying roads has always enjoyed a symbiotic relationship with that of the scientific and technological developments concerning the automobile.
Mud roads were adequate when the favoured mode of travel was by horse or horse driven carriages, but once the motor car became cheap and popular because of Henry Ford the science of laying roads was also reconfigured.
Today, roads are laid out in asphalt or concrete to provide a smooth and safe ride. Modern express ways are laid out to counter both centripetal and centrifugal forces. Night driving has become safer because the lanes are painted in fluorescent colors.
Similarly, cars have become safer because of collapsible steering wheels and airbags, not to mention the standard safety belts and neck rest. Hydraulic and anti locking brakes help prevent major pile ups on the expressways.
These are just a few of the ways in which roads and cars have become safer.
As the usage, power and speed of cars have increased over the time the vulnerability of cars to accidents leading to major loss of life has also increased. Thus the need to improve car safety has also grown with the development of automobiles.
The problems of car safety has been addressed by car manufactures and governmental agencies in many different ways. This includes:
Building better and safer roads including better traffic management system.
Incorporating better car safety features in car designs. For example, equipping cars with such safety features as safety belts and shatterproof windows, provision of collapsible steering column, and bumpers with improved capacity to absorb the impact of collisions.
Introducing laws to improve various safety features of cars, roads and traffic systems. For example, governments specify essential safety features that all manufactures must incorporate in their cars. Similarly steps are taken by government for better enforcement of safe driving regulations.
Promoting safe driving practices and use of car safety features such as seat belts.
Manufacturers and governments spend large sums of money to find ways of improving car safety. Government
Good driving practice is the most important ingredient of car safety. This method of car and road safety is mostly under control of individuals. Although, right kind of driving regulations and their enforcement also helps in promoting more responsible and safe driving behavior.