diff --git a/packages/router/src/apply_redirects.ts b/packages/router/src/apply_redirects.ts
index 3a801227ca..cee485c375 100644
--- a/packages/router/src/apply_redirects.ts
+++ b/packages/router/src/apply_redirects.ts
@@ -18,8 +18,8 @@ import {map} from 'rxjs/operator/map';
 import {mergeMap} from 'rxjs/operator/mergeMap';
 import {EmptyError} from 'rxjs/util/EmptyError';
 
-import {InternalRoute, Route, Routes} from './config';
-import {LoadedRouterConfig, RouterConfigLoader} from './router_config_loader';
+import {InternalRoute, LoadedRouterConfig, Route, Routes} from './config';
+import {RouterConfigLoader} from './router_config_loader';
 import {PRIMARY_OUTLET, Params, defaultUrlMatcher, navigationCancelingError} from './shared';
 import {UrlSegment, UrlSegmentGroup, UrlSerializer, UrlTree} from './url_tree';
 import {andObservables, forEach, waitForMap, wrapIntoObservable} from './utils/collection';
diff --git a/packages/router/src/config.ts b/packages/router/src/config.ts
index 6e0207d952..b80bf3eb85 100644
--- a/packages/router/src/config.ts
+++ b/packages/router/src/config.ts
@@ -6,13 +6,11 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {NgModuleFactory, Type} from '@angular/core';
+import {NgModuleFactory, NgModuleRef, Type} from '@angular/core';
 import {Observable} from 'rxjs/Observable';
-
 import {PRIMARY_OUTLET} from './shared';
 import {UrlSegment, UrlSegmentGroup} from './url_tree';
 
-
 /**
  * @whatItDoes Represents router configuration.
  *
@@ -359,11 +357,17 @@ export interface Route {
   children?: Routes;
   loadChildren?: LoadChildren;
   runGuardsAndResolvers?: RunGuardsAndResolvers;
+  /** @internal */
+  _loadedConfig?: LoadedRouterConfig;
+}
+
+export class LoadedRouterConfig {
+  constructor(public routes: Route[], public module: NgModuleRef<any>) {}
 }
 
 export interface InternalRoute extends Route {
   // `LoadedRouterConfig` loaded via a Route `loadChildren`
-  _loadedConfig?: any;
+  _loadedConfig?: LoadedRouterConfig;
 }
 
 export function validateConfig(config: Routes, parentPath: string = ''): void {
diff --git a/packages/router/src/router.ts b/packages/router/src/router.ts
index d4ad6aa330..f059b39e67 100644
--- a/packages/router/src/router.ts
+++ b/packages/router/src/router.ts
@@ -22,14 +22,14 @@ import {mergeMap} from 'rxjs/operator/mergeMap';
 import {reduce} from 'rxjs/operator/reduce';
 
 import {applyRedirects} from './apply_redirects';
-import {InternalRoute, QueryParamsHandling, ResolveData, Route, Routes, RunGuardsAndResolvers, validateConfig} from './config';
+import {InternalRoute, LoadedRouterConfig, QueryParamsHandling, ResolveData, Route, Routes, RunGuardsAndResolvers, validateConfig} from './config';
 import {createRouterState} from './create_router_state';
 import {createUrlTree} from './create_url_tree';
 import {RouterOutlet} from './directives/router_outlet';
 import {Event, NavigationCancel, NavigationEnd, NavigationError, NavigationStart, RouteConfigLoadEnd, RouteConfigLoadStart, RoutesRecognized} from './events';
 import {recognize} from './recognize';
 import {DetachedRouteHandle, DetachedRouteHandleInternal, RouteReuseStrategy} from './route_reuse_strategy';
-import {LoadedRouterConfig, RouterConfigLoader} from './router_config_loader';
+import {RouterConfigLoader} from './router_config_loader';
 import {RouterOutletMap} from './router_outlet_map';
 import {ActivatedRoute, ActivatedRouteSnapshot, RouterState, RouterStateSnapshot, advanceActivatedRoute, createEmptyState, equalParamsAndUrlSegments, inheritedParamsDataResolve} from './router_state';
 import {PRIMARY_OUTLET, Params, isNavigationCancelingError} from './shared';
diff --git a/packages/router/src/router_config_loader.ts b/packages/router/src/router_config_loader.ts
index 943ea62111..b91bd28b5c 100644
--- a/packages/router/src/router_config_loader.ts
+++ b/packages/router/src/router_config_loader.ts
@@ -12,7 +12,7 @@ import {fromPromise} from 'rxjs/observable/fromPromise';
 import {of } from 'rxjs/observable/of';
 import {map} from 'rxjs/operator/map';
 import {mergeMap} from 'rxjs/operator/mergeMap';
-import {LoadChildren, Route} from './config';
+import {LoadChildren, LoadedRouterConfig, Route} from './config';
 import {flatten, wrapIntoObservable} from './utils/collection';
 
 /**
@@ -21,10 +21,6 @@ import {flatten, wrapIntoObservable} from './utils/collection';
  */
 export const ROUTES = new InjectionToken<Route[][]>('ROUTES');
 
-export class LoadedRouterConfig {
-  constructor(public routes: Route[], public module: NgModuleRef<any>) {}
-}
-
 export class RouterConfigLoader {
   constructor(
       private loader: NgModuleFactoryLoader, private compiler: Compiler,
diff --git a/packages/router/src/router_preloader.ts b/packages/router/src/router_preloader.ts
index c8ed0a2f0f..7c897c87f8 100644
--- a/packages/router/src/router_preloader.ts
+++ b/packages/router/src/router_preloader.ts
@@ -6,7 +6,7 @@
 *found in the LICENSE file at https://angular.io/license
 */
 
-import {Compiler, Injectable, Injector, NgModuleFactoryLoader, NgModuleRef} from '@angular/core';
+import {Compiler, Injectable, Injector, NgModuleFactoryLoader, NgModuleRef, OnDestroy} from '@angular/core';
 import {Observable} from 'rxjs/Observable';
 import {Subscription} from 'rxjs/Subscription';
 import {from} from 'rxjs/observable/from';
@@ -16,8 +16,8 @@ import {concatMap} from 'rxjs/operator/concatMap';
 import {filter} from 'rxjs/operator/filter';
 import {mergeAll} from 'rxjs/operator/mergeAll';
 import {mergeMap} from 'rxjs/operator/mergeMap';
-import {InternalRoute, Route, Routes} from './config';
-import {NavigationEnd, RouteConfigLoadEnd, RouteConfigLoadStart} from './events';
+import {InternalRoute, LoadedRouterConfig, Route, Routes} from './config';
+import {Event, NavigationEnd, RouteConfigLoadEnd, RouteConfigLoadStart} from './events';
 import {Router} from './router';
 import {RouterConfigLoader} from './router_config_loader';
 
@@ -73,7 +73,7 @@ export class NoPreloading implements PreloadingStrategy {
  * @stable
  */
 @Injectable()
-export class RouterPreloader {
+export class RouterPreloader implements OnDestroy {
   private loader: RouterConfigLoader;
   private subscription: Subscription;
 
@@ -87,8 +87,8 @@ export class RouterPreloader {
   };
 
   setUpPreloading(): void {
-    const navigations = filter.call(this.router.events, (e: any) => e instanceof NavigationEnd);
-    this.subscription = concatMap.call(navigations, () => this.preload()).subscribe(() => {});
+    const navigations$ = filter.call(this.router.events, (e: Event) => e instanceof NavigationEnd);
+    this.subscription = concatMap.call(navigations$, () => this.preload()).subscribe(() => {});
   }
 
   preload(): Observable<any> {
@@ -121,8 +121,8 @@ export class RouterPreloader {
 
   private preloadConfig(ngModule: NgModuleRef<any>, route: InternalRoute): Observable<void> {
     return this.preloadingStrategy.preload(route, () => {
-      const loaded = this.loader.load(ngModule.injector, route);
-      return mergeMap.call(loaded, (config: any): any => {
+      const loaded$ = this.loader.load(ngModule.injector, route);
+      return mergeMap.call(loaded$, (config: LoadedRouterConfig) => {
         route._loadedConfig = config;
         return this.processRoutes(config.module, config.routes);
       });
diff --git a/packages/router/test/apply_redirects.spec.ts b/packages/router/test/apply_redirects.spec.ts
index 4212f203f8..fb06c2d0cd 100644
--- a/packages/router/test/apply_redirects.spec.ts
+++ b/packages/router/test/apply_redirects.spec.ts
@@ -12,8 +12,7 @@ import {Observable} from 'rxjs/Observable';
 import {of } from 'rxjs/observable/of';
 
 import {applyRedirects} from '../src/apply_redirects';
-import {Routes} from '../src/config';
-import {LoadedRouterConfig} from '../src/router_config_loader';
+import {LoadedRouterConfig, Routes} from '../src/config';
 import {DefaultUrlSerializer, UrlSegmentGroup, UrlTree, equalSegments} from '../src/url_tree';
 
 describe('applyRedirects', () => {
diff --git a/tools/public_api_guard/router/router.d.ts b/tools/public_api_guard/router/router.d.ts
index 80b574e659..0387427f58 100644
--- a/tools/public_api_guard/router/router.d.ts
+++ b/tools/public_api_guard/router/router.d.ts
@@ -354,7 +354,7 @@ export declare class RouterOutletMap {
 }
 
 /** @stable */
-export declare class RouterPreloader {
+export declare class RouterPreloader implements OnDestroy {
     constructor(router: Router, moduleLoader: NgModuleFactoryLoader, compiler: Compiler, injector: Injector, preloadingStrategy: PreloadingStrategy);
     ngOnDestroy(): void;
     preload(): Observable<any>;