Motorcycles will still be free but I thought it was useful for you to know  if you are heading that way in  car etc:-

From October 2014 they are changing the way you pay the Dartford Crossing charge. You will no longer pay at the barriers; instead you’ll be able to pay in advance, or before midnight the day after crossing. Drivers who don’t pay will face a penalty charge.

The new scheme is known as Dart Charge and will help to reduce congestion at the crossing.

It will still be free to use the crossing between 10pm and 6am.

How to pay

There will be lots of ways to pay:

•with a pre-pay account

•online

•by text

•at retail outlets

•over the phone

•by post

Pre-pay accounts

You will be able to save up to a third on every crossing by setting up a pre-pay account. Accounts can be topped up manually or you can set up auto top ups to come by direct debit, or from your debit or credit card whenever a set threshold is reached.

Your vehicle registration must be associated with your account and sufficient funds will need to be available to cover the crossing. You can allocate multiple vehicles to an account as long as you register each one.