Geospatial - Bus Direction on Google Map

Hi there, My Project Description : I have Latitude and longitude stored in my database for a Bus route. Using that Latitude and longitude I am plotting Bus Route on Google Map using ASP.NET, C# and Google API. Now I have a functionality by which a user can Draw a lines on Google Map(That line has an arrow, check the attached screen shot) and when he clicks SUBMIT button, all the bus which are passing through that lines which is drawn on Google map by the user are Shown on the map when the user draws lines and clicks Submit button. Right now my code is working fine and displaying all the buses passing through that lines but I am unable to find the direction of my arrow. Please check the attached screen shot. That might help a lot. Message me if you have any questions. Cheers, Rushir