Principals are often responsive to requests from parents with children attending the school, parent groups like the PTA and from the larger community. Consider approaching the principal early in the SRTS planning process so he or she feels included. If a principal isn't interested, it is usually a good idea to keep this person in the loop as the program progresses. This not only shows your desire to work cooperatively, it also makes it easier if and when the principal wants to lend support.
Most people and organizations are strongly motivated by self-interest. This is the basis of advertising and social marketing. If a cause like SRTS seems irrelevant or unimportant, gaining support will need to involve sharing information about SRTS and demonstrating how it will benefit the school and the students. Use available resources to help the principal and others understand "how they will benefit." Identify and publicize as many benefits as you can so that everyone can find something appealing. Ask potential partners to identify additional benefits you may have overlooked. After pointing out the numerous benefits, acknowledge that potential disadvantages must be addressed as well. Have potential solutions for resolving issues like loss of parking spaces.