Undertaking

I understand why the cyclists undertake but it must be very hard for the vehicle drivers to see them.

This is the number 521 bus. I can catch it to and from Waterloo. I was going to catch it this morning as I wasn't feeling 100% but the queue was so long that I walked. This is in the evening and its heading towards Waterloo. The amount of traffic usually means that I can get back to the station before it.