Passing few query string parameters can land the user on the Google Maps Page with Driving Directions.
f: stands for “form” and controls the style of query form to be displayed.
f=d: Displays the “directions” form (two input boxes: from, to).
saddr: “saddr” source address. Use this when asking for driving directions.
daddr: “daddr” Destination address(es). Use this when asking for driving directions.
More detailed article on the Google Maps Query Strings: