The funny thing about hazards in video games is that once you mention them, everyone always thinks it’s automatically a thing you want to stay away from. Maybe it’s the name, but regardless, there are instances of hazards in a video game map being used to your benefit. For example, red barrels being shot to explode enemies. While there may not be any red barrels in Knockout City, there are plenty of hazards, and you can often use them. For the Hit and Run and Traffic Circle secret achievements/trophies, you can ride one and get some Gamerscore out of it.
To get the Hit and Run secret achievement or trophy, all you need to do is land the final hit on a knockout while riding a vehicle in the map Knockout Roundabout. Simply put, all you need to do is be standing on top of a car while a throw from you knocks out a player. Be sure to take advantage of the slight height advantage to give you a better lob ball throw or curve it around other vehicles.
As for the Traffic Circle secret achievement, all you need to do is ride on top of one car for the duration of an entire lap around the map, again on Knockout Roundabout. This one can rely a little more on luck because if you get knocked into the air by an enemy, your counter for the achievement will start over. Our best advice is to make sure you have your timing down to catch any thrown balls and hope no one comes close to tackle you off the vehicle.