I have been taking public transportation for many months now.
The advantage is that I can use the time spent doing nothing while in the train to research fajing. One simple but powerful method of fajing that can be practiced on an MRT in full view of passengers is one which involves the force model explained on Page 101 in TaijiKinesis Vol 2. Whether the train is crowded or not as long as I get to stand in my normal spot I can do the practice.
In the event, I cannot stand in my normal spot then I will practice another method which is similar to the White Crane Spreads Wings posture from Grandmaster Wei Shuren’s style. The posture may be different but the same model from Page 101 can be used.
There is another lesson that can be learned here and that is how to receive power and return it in conformance to the principle of receiving force do not use wrists, releasing force send it out at once.
Since my student drives, I mentioned about using the steering wheel as an aid in understanding how to generate power.
The key above, as always, is to use the intention to teach the body how to move accurately.