When using your Apple Watch to pay for transit, hold the display of your Apple Watch within a few centimeters of the middle of the contactless reader until you feel a vibration. As payment confirmation, you will see “Done” and a check-mark on the display of your mobile device.
You can have a payment card and a transit card enabled for Express Transit mode in the same city.
For more information on how to setup Apple Pay, visit the Apple Support website.