Many to Many

organization.rb

class Organization < ActiveRecord::Base
  has_many :projects
  has_many :contacts
end

# Organizations would have many projects that they are the Owner for (a university with many projects)
# or the Organization could be a firm that is working on the project (A/E, or Construction Manager)
# In both cases, these are roles again.
# contacts will also have roles both at the organization (position title) and on the project (Owner's Rep, etc.)

people.rb

class Contact < ActiveRecord::Base
  has_many :projects
  has_many :organizations
end

# Contact would have a role in projects (i.e. The Project Manager)
# Contact would be an employee of a parent company

project.rb

class Project < ActiveRecord::Base
  has_many :contacts
  has_many :organizations
end

# Organizations would have a role on a project like (Architect, Construction Manager, etc.)
# Contacts would have a role on the project like (Project Superintendent)