Find Routes within Range of a Point

Question

I am seeking a way using Google Maps to take a predefined latlng point and find routes that pass within 20 miles. The start and end points for the route exist in a MySQL DB.

1. Would it be best, when storing the routes, to include all the polylines that make up the route?
2. Should I store the RouteBoxer coordinates and find all boxes that contain the predefined latlng point? This may be up to 3x greater distance then 20 miles
3. How should I store the data for both predefined latlng points and the route information?

EDIT:

This article may bring some ideas but I am still unsure of the best method? I am concerned with scaling because I am thinking of 50,000+ routes and thousands of routes.

--> Find how many (googlemap) polygons near x distance of a point

--> Get polygons close to a lat,long in MySQL

--> MySQL Find Polygon Nearest to Point

Thanks very much!

David