Angular 2.0, how to detect route change on child component

Create a global service that subscribes to router and inject the service wherever you want to know about route changes. The service can expose changes by an Observable itself so interested components also can subscribe to get notified automatically.

RC3+ solution:

constructor(private router: Router) {
  router.events.subscribe(event => {
    if (event.constructor.name === 'NavigationStart') {
      console.log(event.url);
    }
  });
}

Alternatively, you can filter for the NavigationStart event using the filter pipe (RxJS 6+):

constructor(private router: Router) {
  router.events.pipe(
    filter(event => event instanceof NavigationStart),
  ).subscribe((event: NavigationStart) => {
    console.log(event.url);
  });
}