The Big Dictionary of Dreams

by Martha Clarke
A collision with another person warns against the possibility of becoming hated because of your desire for advancement at any cost. If, however, someone collides with you, tensions will occur around you and you will be involved in many altercations.

If you dream of two vehicles crashing this points to a foreseeable period of bad luck.

Strangest Dream Explanations

by Dream Explanations - Anonymous
Dreams of a collision symbolize an intersection of energy that is either serendipitous or injurious.

If someone is hurt in the collision, as in an auto accident, this can represent a wake-up call, telling you to pay attention and become more responsible.

See Accident.

Ten Thousand Dream Interpretation

by Gustavus Hindman Miller
To dream of a collision, you will meet with an accident of a serious type and disappointments in business.

For a young woman to see a collision, denotes she will be unable to decide between lovers, and will be the cause of wrangles.