Set parameters in URL dynamically Angularjs2

Question

I need to set some values dynamically in a URL. The code i have now

export class AccountService {

private accounts;
private URL="";

constructor(private http: Http) {
  this.URL =   "http://payd.azurewebsites.net/api/User/"+localStorage.getItem("paydid")+"/accou nt";
  console.log(localStorage.getItem("paydid"));
}

httpGet(): Observable<Account> {
  var headers = new Headers();
  headers.append('Authorization', 'bearer ' + localStorage.getItem('token'));
  headers.append('Content-Type', 'application/x-www-form-urlencoded');

  return this.http.get(this.URL, {
    headers: headers
  }).catch((error: any, caught: Observable<any>) => {
      return Observable.throw(error);
    })
  .map((response: Response) => response.json());
  }
}

Im trying to set the value like this in url this.URL = "http://payd.azurewebsites.net/api/User/"+localStorage.getItem("paydid")+"/account". But this gives me something like this http://payd.azurewebsites.net/api/User/%221%22/account. In console.log() it show the correct value of localStorage.getItem("paydid"). How to do this correctly? Thanks!