To encourage more people to use mass transit, ads from providers of mass transportation compare the ease and comfort of riding mass transit with the difficulties of driving in congested traffic and parking headaches. With respect to the positioning strategies, these mass transportation providers are making use of positioning by

Product Class

Explanation:

The product class positioning strategy consists in the comparison between two classes of products that are substitutes of each other, with the goal of highlighting the advantages of one over the other.

Mass transit is a substitute for private transit because they both have the same basic goal: allowing a person to move from one place to the other.

Those who are pro-mass transit then, try to highlight what makes mass transit different, or better, from individual transit. (more comfort, less traffic, less parking headaches, etc).