diff --git a/modules/angular2/alt_router.ts b/modules/angular2/alt_router.ts
index 0aa7ea79f4..d7ea77a688 100644
--- a/modules/angular2/alt_router.ts
+++ b/modules/angular2/alt_router.ts
@@ -5,7 +5,7 @@
  */
 
 export {Router, RouterOutletMap} from './src/alt_router/router';
-export {RouteSegment, UrlSegment, Tree} from './src/alt_router/segments';
+export {RouteSegment, UrlSegment, Tree, UrlTree, RouteTree} from './src/alt_router/segments';
 export {Routes} from './src/alt_router/metadata/decorators';
 export {Route} from './src/alt_router/metadata/metadata';
 export {
diff --git a/modules/angular2/src/alt_router/interfaces.ts b/modules/angular2/src/alt_router/interfaces.ts
index 8d5a35aae4..c09b38df5f 100644
--- a/modules/angular2/src/alt_router/interfaces.ts
+++ b/modules/angular2/src/alt_router/interfaces.ts
@@ -1,11 +1,10 @@
-import {RouteSegment, Tree} from './segments';
+import {RouteSegment, Tree, RouteTree} from './segments';
 
 export interface OnActivate {
-  routerOnActivate(curr: RouteSegment, prev?: RouteSegment, currTree?: Tree<RouteSegment>,
-                   prevTree?: Tree<RouteSegment>): void;
+  routerOnActivate(curr: RouteSegment, prev?: RouteSegment, currTree?: RouteTree,
+                   prevTree?: RouteTree): void;
 }
 
 export interface CanDeactivate {
-  routerCanDeactivate(currTree?: Tree<RouteSegment>,
-                      futureTree?: Tree<RouteSegment>): Promise<boolean>;
+  routerCanDeactivate(currTree?: RouteTree, futureTree?: RouteTree): Promise<boolean>;
 }
\ No newline at end of file
diff --git a/modules/angular2/src/alt_router/link.ts b/modules/angular2/src/alt_router/link.ts
index 1b151aef42..88e1b4d12b 100644
--- a/modules/angular2/src/alt_router/link.ts
+++ b/modules/angular2/src/alt_router/link.ts
@@ -1,9 +1,9 @@
-import {Tree, TreeNode, UrlSegment, RouteSegment, rootNode} from './segments';
+import {Tree, TreeNode, UrlSegment, RouteSegment, rootNode, UrlTree, RouteTree} from './segments';
 import {isBlank, isPresent, isString, isStringMap} from 'angular2/src/facade/lang';
 import {ListWrapper} from 'angular2/src/facade/collection';
 
-export function link(segment: RouteSegment, routeTree: Tree<RouteSegment>,
-                     urlTree: Tree<UrlSegment>, change: any[]): Tree<UrlSegment> {
+export function link(segment: RouteSegment, routeTree: RouteTree, urlTree: UrlTree,
+                     change: any[]): UrlTree {
   if (change.length === 0) return urlTree;
 
   let startingNode;
@@ -29,10 +29,10 @@ export function link(segment: RouteSegment, routeTree: Tree<RouteSegment>,
   let updated = _update(startingNode, normalizedChange);
   let newRoot = _constructNewTree(rootNode(urlTree), startingNode, updated);
 
-  return new Tree<UrlSegment>(newRoot);
+  return new UrlTree(newRoot);
 }
 
-function _findUrlSegment(segment: RouteSegment, routeTree: Tree<RouteSegment>): UrlSegment {
+function _findUrlSegment(segment: RouteSegment, routeTree: RouteTree): UrlSegment {
   let s = segment;
   let res = null;
   while (isBlank(res)) {
diff --git a/modules/angular2/src/alt_router/recognize.ts b/modules/angular2/src/alt_router/recognize.ts
index 06d91362f1..7d7c85ec87 100644
--- a/modules/angular2/src/alt_router/recognize.ts
+++ b/modules/angular2/src/alt_router/recognize.ts
@@ -1,4 +1,4 @@
-import {RouteSegment, UrlSegment, Tree, TreeNode, rootNode} from './segments';
+import {RouteSegment, UrlSegment, Tree, TreeNode, rootNode, UrlTree, RouteTree} from './segments';
 import {RoutesMetadata, RouteMetadata} from './metadata/metadata';
 import {Type, isBlank, isPresent, stringify} from 'angular2/src/facade/lang';
 import {ListWrapper, StringMapWrapper} from 'angular2/src/facade/collection';
@@ -10,10 +10,9 @@ import {reflector} from 'angular2/src/core/reflection/reflection';
 
 // TODO: vsavkin: recognize should take the old tree and merge it
 export function recognize(componentResolver: ComponentResolver, type: Type,
-                          url: Tree<UrlSegment>): Promise<Tree<RouteSegment>> {
+                          url: UrlTree): Promise<RouteTree> {
   let matched = new _MatchResult(type, [url.root], null, rootNode(url).children, []);
-  return _constructSegment(componentResolver, matched)
-      .then(roots => new Tree<RouteSegment>(roots[0]));
+  return _constructSegment(componentResolver, matched).then(roots => new RouteTree(roots[0]));
 }
 
 function _recognize(componentResolver: ComponentResolver, parentType: Type,
diff --git a/modules/angular2/src/alt_router/router.ts b/modules/angular2/src/alt_router/router.ts
index b5630beac0..65ea6ad595 100644
--- a/modules/angular2/src/alt_router/router.ts
+++ b/modules/angular2/src/alt_router/router.ts
@@ -20,7 +20,8 @@ import {
   equalSegments,
   routeSegmentComponentFactory,
   RouteSegment,
-  Tree,
+  UrlTree,
+  RouteTree,
   rootNode,
   TreeNode,
   UrlSegment,
@@ -36,8 +37,8 @@ export class RouterOutletMap {
 }
 
 export class Router {
-  private _prevTree: Tree<RouteSegment>;
-  private _urlTree: Tree<UrlSegment>;
+  private _prevTree: RouteTree;
+  private _urlTree: UrlTree;
   private _locationSubscription: any;
   private _changes: EventEmitter<void> = new EventEmitter<void>();
 
@@ -49,7 +50,7 @@ export class Router {
     this.navigateByUrl(this._location.path());
   }
 
-  get urlTree(): Tree<UrlSegment> { return this._urlTree; }
+  get urlTree(): UrlTree { return this._urlTree; }
 
   navigateByUrl(url: string): Promise<void> {
     return this._navigate(this._urlSerializer.parse(url));
@@ -66,7 +67,7 @@ export class Router {
         (change) => { this._navigate(this._urlSerializer.parse(change['url'])); });
   }
 
-  private _navigate(url: Tree<UrlSegment>): Promise<void> {
+  private _navigate(url: UrlTree): Promise<void> {
     this._urlTree = url;
     return recognize(this._componentResolver, this._rootComponentType, url)
         .then(currTree => {
@@ -82,7 +83,7 @@ export class Router {
         });
   }
 
-  createUrlTree(changes: any[], segment?: RouteSegment): Tree<UrlSegment> {
+  createUrlTree(changes: any[], segment?: RouteSegment): UrlTree {
     if (isPresent(this._prevTree)) {
       let s = isPresent(segment) ? segment : this._prevTree.root;
       return link(s, this._prevTree, this.urlTree, changes);
@@ -91,11 +92,11 @@ export class Router {
     }
   }
 
-  serializeUrl(url: Tree<UrlSegment>): string { return this._urlSerializer.serialize(url); }
+  serializeUrl(url: UrlTree): string { return this._urlSerializer.serialize(url); }
 
   get changes(): Observable<void> { return this._changes; }
 
-  get routeTree(): Tree<RouteSegment> { return this._prevTree; }
+  get routeTree(): RouteTree { return this._prevTree; }
 }
 
 
@@ -103,7 +104,7 @@ class _LoadSegments {
   private deactivations: Object[][] = [];
   private performMutation: boolean = true;
 
-  constructor(private currTree: Tree<RouteSegment>, private prevTree: Tree<RouteSegment>) {}
+  constructor(private currTree: RouteTree, private prevTree: RouteTree) {}
 
   load(parentOutletMap: RouterOutletMap, rootComponent: Object): Promise<boolean> {
     let prevRoot = isPresent(this.prevTree) ? rootNode(this.prevTree) : null;
diff --git a/modules/angular2/src/alt_router/router_url_serializer.ts b/modules/angular2/src/alt_router/router_url_serializer.ts
index 7757e7f1e5..357480c7bc 100644
--- a/modules/angular2/src/alt_router/router_url_serializer.ts
+++ b/modules/angular2/src/alt_router/router_url_serializer.ts
@@ -1,20 +1,20 @@
-import {UrlSegment, Tree, TreeNode, rootNode} from './segments';
+import {UrlSegment, Tree, TreeNode, rootNode, UrlTree} from './segments';
 import {BaseException} from 'angular2/src/facade/exceptions';
 import {isBlank, isPresent, RegExpWrapper} from 'angular2/src/facade/lang';
 import {ListWrapper} from 'angular2/src/facade/collection';
 
 export abstract class RouterUrlSerializer {
-  abstract parse(url: string): Tree<UrlSegment>;
-  abstract serialize(tree: Tree<UrlSegment>): string;
+  abstract parse(url: string): UrlTree;
+  abstract serialize(tree: UrlTree): string;
 }
 
 export class DefaultRouterUrlSerializer extends RouterUrlSerializer {
-  parse(url: string): Tree<UrlSegment> {
+  parse(url: string): UrlTree {
     let root = new _UrlParser().parse(url);
-    return new Tree<UrlSegment>(root);
+    return new UrlTree(root);
   }
 
-  serialize(tree: Tree<UrlSegment>): string { return _serializeUrlTreeNode(rootNode(tree)); }
+  serialize(tree: UrlTree): string { return _serializeUrlTreeNode(rootNode(tree)); }
 }
 
 function _serializeUrlTreeNode(node: TreeNode<UrlSegment>): string {
diff --git a/modules/angular2/src/alt_router/segments.ts b/modules/angular2/src/alt_router/segments.ts
index 2c9e635b34..72ae311558 100644
--- a/modules/angular2/src/alt_router/segments.ts
+++ b/modules/angular2/src/alt_router/segments.ts
@@ -28,6 +28,14 @@ export class Tree<T> {
   pathFromRoot(t: T): T[] { return _findPath(t, this._root, []).map(s => s.value); }
 }
 
+export class UrlTree extends Tree<UrlSegment> {
+  constructor(root: TreeNode<UrlSegment>) { super(root); }
+}
+
+export class RouteTree extends Tree<RouteSegment> {
+  constructor(root: TreeNode<RouteSegment>) { super(root); }
+}
+
 export function rootNode<T>(tree: Tree<T>): TreeNode<T> {
   return tree._root;
 }
@@ -103,7 +111,7 @@ export class RouteSegment {
   get stringifiedUrlSegments(): string { return this.urlSegments.map(s => s.toString()).join("/"); }
 }
 
-export function serializeRouteSegmentTree(tree: Tree<RouteSegment>): string {
+export function serializeRouteSegmentTree(tree: RouteTree): string {
   return _serializeRouteSegmentTree(tree._root);
 }
 
diff --git a/modules/angular2/test/alt_router/link_spec.ts b/modules/angular2/test/alt_router/link_spec.ts
index fb82a52561..e6c6208c6f 100644
--- a/modules/angular2/test/alt_router/link_spec.ts
+++ b/modules/angular2/test/alt_router/link_spec.ts
@@ -15,7 +15,13 @@ import {
   xit
 } from 'angular2/testing_internal';
 
-import {RouteSegment, UrlSegment, Tree, TreeNode} from 'angular2/src/alt_router/segments';
+import {
+  RouteSegment,
+  UrlSegment,
+  UrlTree,
+  TreeNode,
+  RouteTree
+} from 'angular2/src/alt_router/segments';
 import {link} from 'angular2/src/alt_router/link';
 import {DefaultRouterUrlSerializer} from 'angular2/src/alt_router/router_url_serializer';
 
@@ -88,7 +94,7 @@ export function main() {
       let child = new RouteSegment([], null, null, null, null);
       let root = new TreeNode<RouteSegment>(new RouteSegment([c], {}, null, null, null),
                                             [new TreeNode<RouteSegment>(child, [])]);
-      let tree = new Tree<RouteSegment>(root);
+      let tree = new RouteTree(root);
 
       let t = link(child, tree, p, ["./c2"]);
       expect(parser.serialize(t)).toEqual("/a(aux:ap)/c2(aux:cp)");
@@ -96,7 +102,7 @@ export function main() {
   });
 }
 
-function s(u: UrlSegment): Tree<RouteSegment> {
+function s(u: UrlSegment): RouteTree {
   let root = new TreeNode<RouteSegment>(new RouteSegment([u], {}, null, null, null), []);
-  return new Tree<RouteSegment>(root);
+  return new RouteTree(root);
 }
\ No newline at end of file
diff --git a/modules/angular2/test/alt_router/recognize_spec.ts b/modules/angular2/test/alt_router/recognize_spec.ts
index 4c92cf4ace..cce26e0ea1 100644
--- a/modules/angular2/test/alt_router/recognize_spec.ts
+++ b/modules/angular2/test/alt_router/recognize_spec.ts
@@ -18,7 +18,7 @@ import {
 import {recognize} from 'angular2/src/alt_router/recognize';
 import {Routes, Route} from 'angular2/alt_router';
 import {provide, Component, ComponentResolver} from 'angular2/core';
-import {UrlSegment, Tree} from 'angular2/src/alt_router/segments';
+import {UrlSegment, RouteTree, UrlTree} from 'angular2/src/alt_router/segments';
 import {DefaultRouterUrlSerializer} from 'angular2/src/alt_router/router_url_serializer';
 import {DEFAULT_OUTLET_NAME} from 'angular2/src/alt_router/constants';
 
@@ -192,7 +192,7 @@ export function main() {
   });
 }
 
-function tree(url: string): Tree<UrlSegment> {
+function tree(url: string): UrlTree {
   return new DefaultRouterUrlSerializer().parse(url);
 }
 
diff --git a/modules/playground/src/alt_routing/inbox-app.ts b/modules/playground/src/alt_routing/inbox-app.ts
index 179468ed86..87adaf8da3 100644
--- a/modules/playground/src/alt_routing/inbox-app.ts
+++ b/modules/playground/src/alt_routing/inbox-app.ts
@@ -7,7 +7,8 @@ import {
   ROUTER_PROVIDERS,
   OnActivate,
   RouteSegment,
-  Tree,
+  RouteTree,
+  UrlTree
 } from 'angular2/alt_router';
 import * as db from './data';
 import {Location} from 'angular2/platform/common';
@@ -99,8 +100,8 @@ class InboxDetailCmp implements OnActivate {
 
   constructor(private _db: DbService) {}
 
-  routerOnActivate(curr: RouteSegment, prev?: RouteSegment, currTree?: Tree<RouteSegment>,
-                   prevTree?: Tree<RouteSegment>): void {
+  routerOnActivate(curr: RouteSegment, prev?: RouteSegment, currTree?: RouteTree,
+                   prevTree?: RouteTree): void {
     let id = curr.getParam("id");
     this._db.email(id).then(data => this.record.setData(data));
   }
@@ -113,8 +114,8 @@ class InboxCmp implements OnActivate {
 
   constructor(private _db: DbService) {}
 
-  routerOnActivate(curr: RouteSegment, prev?: RouteSegment, currTree?: Tree<RouteSegment>,
-                   prevTree?: Tree<RouteSegment>): void {
+  routerOnActivate(curr: RouteSegment, prev?: RouteSegment, currTree?: RouteTree,
+                   prevTree?: RouteTree): void {
     var sortType = curr.getParam('sort');
     var sortEmailsByDate = isPresent(sortType) && sortType == "date";