Your desired URL format can easily be achieved with a regular expression route:
resources.router.routes.new_project.type = "Zend_Controller_Router_Route_Regex"
resources.router.routes.new_project.route = "project/new-(\d+)"
resources.router.routes.new_project.defaults.controller = "project"
resources.router.routes.new_project.defaults.module = "site"
resources.router.routes.new_project.defaults.action = "new"
resources.router.routes.new_project.map.1 = "project_type_id"
resources.router.routes.new_project.reverse = "project/new-%s"
You can then access the ID using $this->_getParam('project_type_id')
in your controller.