I have deployed my WCF webservice locally and its working fine, But in a method I got unexpected result so I decided to debug my webservice in
Are you sure, that your're debugging the service with an elevated account? This error is quite common if you're trying to host a service on a non-default port using a standard user.
You could try to register that port to that specific user. Open an elevated command prompt and execute the follwing command:
add urlacl url=http://localhost:61241/TaxiRiderService user=YOURDOMAIN\youruser
For details have a look at: http://msdn.microsoft.com/en-us/library/windows/desktop/cc307223%28v=vs.85%29.aspx