In 1935, according to official registration figures, there were almost 26.5 million vehicles on American roads. Just fifteen years later, buoyed by post-World War II economic expansion, that figure had swollen to in excess of 49 million - an 85 per cent hike.
The vast increases in the number of cars, buses and trucks didn't show any signs of abating, either. By 1955, nearly another 14 million vehicles had been registered.
Somewhat predictably, the number of accidents occurring rose at an alarming rate. The demand and need for improvements in safety consequently led to many related developments during the 1950s, such as padded dashboards, collapsible steering columns, seat belts and shock-absorbing bumpers. Many of these would ultimately become standard-fit features and save countless lives.
Some, however, were looking at ways to prevent accidents happening in the first place. Following World War II, many companies were investigating ways to utilise and monetise some of the technological innovations of the war. Jet engines, cyanoacrylate adhesives, fuel injection, telecommunications systems, night vision, new materials and technologies all found commercial and civilian applications.
Electronics specialist RCA, which had been involved in many advanced projects during the war, was similarly studying ways in which to capitalise on its new-found expertise. It promptly set up numerous new research branches, one of which was the 'Government Radar Engineering' department.
One of the assistant engineers in this department - which seemingly developed systems for both defence and domestic purposes - was radar and radio specialist Nathaniel Korman. He had previously led RCA's radar and television development division and, like others in the company, was investigating ways that these new technologies could be applied to defence, development and transport systems.
Most of Korman's work at this time, aside from his hardware-related developments, focused on the concept of improving the flow of traffic by using radar-based speed control systems. Several of his radar control projects focused on trains, in particular, as this approach could permit better control of their average speed and junction usage - which would improve traffic flow and the capacity of the network in question.
He also noted that this could be applied to any type of road-going vehicle. 'The invention utilises a radar system, the system being carried by the vehicle to be controlled,' stated Korman. 'The radar system develops a voltage dependent on the distance to the preceding vehicle. This voltage is compared with a voltage dependent on the velocity of the vehicle; the vehicle is controlled in accordance with the results of the comparison.'
This configuration, of a vehicle receiving a signal from a radar unit and that then being used to effect a change in the vehicle's control system, was detailed in a patent submitted in 1948. It was then granted in 1955; later, the Studebaker-Packard Corporation, General Motors, Bendix, Ford, Toyota and Bosch would all reference Korman's work in related developments.
As it became clear that radar had civilian applications outside of aviation, and as buyers and government bodies alike continued to campaign for improvements in road safety, interest in using radar for automotive applications grew.
Inventor George Rashid was the first to detail an automated radar-based braking system, specifically for use for cars, submitting a patent for an 'automatic vehicle control system' in 1954. He lived near Lake Michigan and dense fog was often a problem on local roads, causing people to plough into obstacles or vehicles they simply hadn't seen.
A radar system, in similar conditions, would be able to 'see' through the fog and stop the vehicle if required - or at least warn a driver of the presence of an obstacle. Rashid had also observed the problem of driver inattentiveness during long journeys on the nation's new 'super-highway' roads, as well as issues with older drivers with slower reactions or weaker eyesight, and deemed automation the solution.
Radar engineer Paul Dudeck helped develop Rashid's system, which could cut the car's throttle and apply the brakes if it deemed a collision imminent. This wasn't just some pie-in-the-sky concept, mind; Rashid's system is reported to have proved its capabilities in several tests and drew much praise from those who tried it.
What reportedly stopped its development, at the time, were concerns about reliability and liability. If a radar-brake equipped car mistakenly decided it needed to execute a swift emergency stop, causing everyone behind to plough into it, then there could be some fairly significant legal battles.
The set-up also depended on a vast number of vacuum tubes which made it costly, bulky and difficult to commercialise. Unfortunately, this - in conjunction with the potential legal issues - meant that Rashid's system would never make it to the market.
Worse was to come, though; his sons, following his death, modernised the system with compact transistors and integrated circuits in the mid-1970s. They then set about defrauding a plethora of investors over the course of several years, raising money to live extravagant lifestyles and doing little to bring the functioning, worthwhile technology to the market.
This may well have curtailed some manufacturers' enthusiasm for automatic braking systems. Rashid's concept didn't entirely go to waste, though; Mercedes-Benz, Honda, Bosch, Toyota and several other major manufacturers would, as was the case with Korman's idea, reference this design and its execution in automated safety systems which were developed later.
That said, other manufacturers had been working on radar-based braking systems since the '50s. The Studebaker-Packard Corporation had come up with a system similar to Rashid's in 1956; it used a small radar, mounted in the car's grille, the signals from which would be processed and used to electronically actuate the car's master cylinder to apply the brakes.
This led to the magazine Popular Mechanics questioning whether radar-controlled brakes would arrive in production form in 1957. They didn't, unsurprisingly, as the system proved too costly and unworkable for mainstream production; one source cites a potential cost of $300, which in 1956 would have been equivalent to some £2,640 today. Bear in mind that, in '56, upgrading your Thunderbird to feature power steering, power brakes, electric windows, windshield washers and a radio would cost less than that amount.
General Motors also showcased a radar-based system in its 1959 Cadillac Cyclone Concept, which featured two radars - developed by the Delco Radio Division - tucked inside prominent 'twin dome' assemblies. The electronics driven by these generated a tone and triggered a warning light when the car closed on an object.
Again, expense and reliability were claimed as the major stoppage in taking the system to market. GM's engineers had also noted another problem, though; the fact that the system, due to its capabilities, caused drivers to pay less attention to the road ahead.
Engineer Joe Bidwell, who later became executive director of the General Motors Research Laboratories, spoke to Popular Mechanics in 1958 on the subject; he stated the following prescient warning: "Everybody imagines a system that will let him read a magazine while he drives a superhighway at 70 miles an hour. When we put that into a car, people will read magazines, or even lean back and go to sleep."
Chrysler had discovered similar, in particular that drivers would often assume the system would do their entire job for them - resulting in a shunt. Despite this, development continued throughout the '60s and '70s, with companies such as RCA and Bendix continuing to trial radar-based systems.
Bendix's engineers, like GM's, stated that more work was needed to ensure benefits were delivered without compromising safety. Government bodies were similarly sceptical, with the National Highway Traffic Safety Administration suggesting that - even by the 1980s - a bug-free system would be at least a decade away.
Ultimately, it took until 1992 for a basic distance-ranging safety system to make its way to market - in, of all things, the 1992 Mitsubishi Debonair; its laser-based 'Distance Warning' would simply deliver an alert to the driver if the car in front was getting too close.
This forward collision warning system was shortly followed by the Mitsubishi Diamante's 'Preview Distance Control', which would close the throttle and change down in order to slow the car and provide more reaction time.
These adaptive cruise control systems developed quickly and, by 1999 - in the case of Mercedes-Benz's radar-based 'Distronic' set-up - they were capable of partially applying the brakes to maintain a safe distance to the car in front.
The extension of these systems to provide emergency braking was a logical one, given that all the hardware was present - and it was Honda, in May 2003, that first delivered a radar-based automatic braking system. Its 'Collision Mitigation Braking System', fitted to the fourth-gen Inspire, could deploy light or heavy braking in order to avoid a crash - or, at least, reduce the severity of the collision.
Toyota, Mercedes and Volvo were not far behind and, over the course of the next few years as the cost of the hardware fell and safety requirements continued to climb, several other manufacturers began to deploy emergency braking systems.
The benefit of these autonomous emergency braking systems, which continue to be developed to operate over a wider range of speeds and in more challenging conditions, is not to be underestimated. Studies carried out in the US, for example, indicated that autonomous emergency braking could mitigate 70 per cent of rear-end crashes and almost 50 per cent of fatal crashes. Consequently, 20 manufacturers have already committed to making AEB standard in American-market cars by 2022.