Google announced on Google+ that now you get all four transportation modes (car, transit, biking or walking) in a single traffic card in the Google search app.
Now Google Search can show you all of your options and estimated travel times on a single card. Just tap the mic and say “Ok Google, what’s the traffic like to AT&T Park” and easily switch between transportation modes to determine which route works best for you.
Here is an animated GIF of it in action:
All you have to do is toggle between those modes.
Forum discussion at Google+.