The problem seems to occur in all the tiles with curved roads. They only have the fake tree shadows coming from the 'long' tree egdes and none from the 'short' ones in the corner. If you are lucky the mesh for the shade texture will consist of four parts and you can select the faces of the corner which doesn't have any shadows and add some by editing the uvw map of those faces alone. If you're not so lucky the whole mesh will just consist of two faces and you'll have to cut out the corner you need to retexture.
In gmax and some other programs like Photoshop Elements the shade01 texture will show as completely black. If you view it with the gimp or irfan view you will see where the shadows are and it will give you an idea which parts of the texture you have to use.
Alternatively you could make an extra shade texture for your tiles which has all the shadows needed for one of the curved road tiles.
You could also take a look at the tiles in the TNO tileset which has some roads on tree terrain and apart from the top of the trees the geometry of the meshes is very similar to what you are making.
Edit: It looks like those tiles have the same problem. tno01_d37_01 is also missing the fake tree shadows in the lower left corner.