Arduino Speedometer Help Pls!!!

Using Arduino Project Guidance
1

Hi!

I'm working on a summer project that requires me to build a speedometer that i can measure pretty accurately the speed of a moving train from the ground.
I have seen a lot of tutorials that measure the speed of a bike or a car which require you to attach the sensors to the actual vehicle but in my case this is not possible.
I am required to create a database of sorts of the actual speeds of different trains.

I am a newbie to the arduino and really urgently need help as to what sensors to use and what sort of approach to take!! :confused:
I have searched a lot and didn't find a sensor that could directly tell me this data. I was planning to use an infrared/ultrasound sensor but am unsure as to how they will work and how to proceed with them and if they will be accurate enough...

Any help and guidance will be enormously appreciated!!! Thank you guys soo much!!

2

Will you be on the train?
Beside the track?
Above the track?

3

AWOL:
Will you be on the train?
Beside the track?
Above the track?

I will be beside the tracks

4

I think your best bet is to buy a radar gun like for baseball.

5

KeithRB:
I think your best bet is to buy a radar gun like for baseball.

:cry: Is there no way i could use like an ultrasonic senor or any other sensor?? I really have to use the arduino... Pls hellpppp!!!! :cry:

6

Hi,
The classic is to have two sensors something like 50 or 100 feet apart. Then you record the time difference, the distance, and calculate speed.

How wide / how many tracks in the location you will be at?

Would this be attended by you or have to run 24-7?

Modulated IR beam probably best. THIS: may work.. You probably need to shield the receiver in a black tube for sunlight applications.

The transmitter on the examples runs on 5V. It could be 4 AA NiMH type cells.

Some how-to, example code HERE:

Let us know what you do...

These look like this:

7

Ultrasonic sensors don't have the range, or doppler capability.

Even this one:

Has a range of only 10 meters - way too close for safety sake.

And you might be able to find a radar gun with a serial output that can be read by the arduino.

8

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9

Also is this to be actually implemented, or just an academic exercise? I ask because you aren't normally allowed access anywhere near a railway line, not officially anyway.

10

Graynomad:
Also is this to be actually implemented, or just an academic exercise? I ask because you aren't normally allowed access anywhere near a railway line, not officially anyway.

Very true - the railroads are getting very touchy about this recently with all the photographers wanting to take pictures of people standing/sitting/etc. on the train tracks (very popular for wedding type shots). You might even be able to get away with a transmitter/receiver together with a reflector on the far side of the tracks (two of them and measure the time between them as was suggested in #5 above). You also need to find out just what the minimum distance is you need to be from the tracks to be legal.

11

you aren't normally allowed access anywhere near a railway line, not officially anyway.

Hmmm.. The (1 track wide) railroad line here in rural Vermont has several bridges over it, some private, some public.

I bet you could suspend a couple of sticks from the bridge on either side without ever entering the railroad right-of-way personally.

Or carefully drop a small mirror in the center of the tracks?