Why does the router redirect to another route when a refresh happens?

I have a survey application built using Ember JS, Firebase and a Torii Adapter for authentication and session management. I'm trying to understand the behavior of a specific route (called the 'takesurvey' route) when it is refreshed.

The related code from the router map (router.js) is given below:

this.route('user', function() {
    this.route('surveys');
    //when uncommented, the line below works but on refresh, 
    //nests the takesurvey page under user
    //this.route('takesurvey', {path: ':survey_id', resetNamespace: true}); 
  });
   //alternatively, uncommenting the line below redirects to user.surveys on refresh but loads the survey in the path (/survey_id)
   //this.route('takesurvey', {path: ':survey_id', resetNamespace: true});