How can we Upgrade the Humble Bike Lane?

Watching a design documentary on Netflix, it got me thinking what could we redesign in the transportation world? Biking is the hot topic on everyone's lips these days, and while the protected bike lane is the ultimate solution, it takes a lot to implement. There are hundreds, if not thousands, or even millions of kilometers of regular bike lanes out there, so I got to thinking if there is something we can do to improve the humble bike lane without changing anything else. Something that could be done quickly and easily with little impact to anyone else. What do you think? Any merit in these ideas? Would you feel safer? Anyone out there feel like a trial project?