Calibration of image without chessboard

I have some set of images of a roadway where I can see roads merging in the end. I want to calibrate this image I know some points in the scene. I don't have chessboard to calibrate. Is there any solution available to calibrate.

[Anand]

What points exactly do you know in the scene? Do you have real-world distances for these points?

[MOHIT]

it is something like this, can you answer?

http://in.mathworks.com/matlabcentral/answers/296267-how-to-measure-area-of-a-rectangle-from-an-image