Transport for London (TfL) are consulting on changes to Westminster Bridge and to the roads at the southern end. It includes the removal of road space for traffic to create reserved space for cyclists.
Westminster Bridge will be reduced to one lane for ordinary traffic and even the white “centre-line” demarcating lanes on the bridge is to be removed.
See picture of how it might look.
You can object to these proposals by going to this web page: https://consultations.tfl.gov.uk/roads/westminster-bridge-south?cid=westminster-bridge-south
But you need to do so before the 22nd December!