I am a year 12 student in Design and Technology and I am looking for a way to get a light beam to be projected off the back of learners vehicle at night on to the road to keep a safe distance (3 seconds) between a vehicle traveling behind.
I’ve thought about that kind of problem before.
Projecting a light beam isn’t hard. Lasers, data projectors, movable spotlights.
Doing it legally is hard; some states constrain the colours and intensities in traffic regulations. Check them.
Pointing it for safety and accuracy is hard, as it depends on relative speed of vehicles, loading balance of vehicle, and slope of road.
If you could describe the project in more detail; is it to encourage the learner to speed up, or to discourage a non-learner tailgating? I’m not sure how it would work from a social perspective. An inadvertently malicious non-learner would tend to follow a trailing beam marker, through pavlovian response.
The light is on the back off the learners car to prevent other drivers tailgating at night time. Also making it visible to see learner drivers at night time.
How does a light on the back of a car prevent tailgating?
To show 3 second gap on the road
How does a three second gap on the road being shown prevent tailgating?
It’s difficult to see the l plate beside the number plate without and number plate light so my project is to show a light using some mechanism to show the led light on the road
Okay, as long as you accept that what you are doing is lighting up the L plate, not changing behaviour of tailing drivers. 
What shape of light beam; what surface area of road must be covered, and to what observed intensity?
How will your system calculate the angle of the beam?
Don’t worry my project is obviously to sophisticated for your understanding.
Chuckle. No, you’re unwilling to be challenged on the details that you plan to design. Do come back when you have done some more design to the point that you need answers. I enjoy such challenges to my understanding.
I have competed all necessary research for my project I was trying to get a range of opinion but you were a complete waste of time.
Do show your research so that you can get a range of opinion. As I said, laser, spotlight, or data projector are the main options. You didn’t have any comment about those options, so my guess is you have an option already selected.
I have used other sights around asking the same question and they were happy to show there concern and not change my project unlike you which you have done tonight
No, I’ve not changed your project. I’m showing my concern by continuing to answer carefully. I’m fine with you doing what you intend, and others here may be able to help you further, but they and I will need answers from you to be able to help you the best way.
So I tried this yesterday on the freeway. When driving, if I leave a three second gap between myself and the car in front, two other people will take the gap.
Nothing beats better driver education and rule enforcement.
Yep nice test. You should trigger some number plate shots from a dashcam for tailgaters to name and shame on youtube. Good work on the project. Do you have a speed measurement mechanism to change the gap based on road speed ?