example guard which returns a UrlTree

new_guard.ts

import { Injectable } from '@angular/core';
import { CanActivate,
         ActivatedRouteSnapshot,
         RouterStateSnapshot,
         Router,
         UrlTree } from '@angular/router';

@Injectable()
export class CanActivateRouteGuard implements CanActivate {

  constructor(private router: Router) {}

  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): boolean | UrlTree {
    const url = 'target';
    const tree: UrlTree = this.router.parseUrl(url);
    return tree;
  }
}