After doing some more research I came across with
this.router.createUrlTree(['../step2'], {relativeTo: this.activatedRoute});
and
this.router.navigate(['../step2'], {relativeTo: this.activatedRoute});
First approach (Router.createUrlTree API) did not work for me, i.e. nothing happened. Second approach (Router.navigate API) works.
Update 2016-10-12
There is another stackoverflow question as well:
- How do I navigate to a sibling route
Update 2016-10-24
Documentation:
- Routing & Navigation (Relative Navigation)
Update 2019-03-08
It seems that there were changes in Angular 7.1. There is an answer in another post how to solve it with Angular 7.1. Please refer to https://stackoverflow.com/a/38634440/42659.