Split/Second

The objective of this is to trigger 50 route changers. You must complete the race in order for it to count towards your total and you can restart the race at the end without having to go through the menus or loose any route changers in the last race.

Here is a list of each track and how many route changers each has
Downtown Central: 1
Airport Terminal: 3
Construction Site: 0
Ferry Wharf: 2
Port Bridge: 1
Airplane Graveyard: 0
Dry Docks: 3
Expressway: 1
Power Plant: 0
Storm Drain: 0
Canyon: 1

The two tracks with the most route changers are Airport Terminal and Dry Docks.

To get all route changers in Airport Terminal, draft your opponents at the start and get as much drift as you can. Trigger the control tower and then gather as much drift on the very wide runway as you can. Do not take the shortcut so you can gather more drift on the normal route. At this point you should have enough to trigger a route change into the underground carpark. Gather more power over the next lap and then trigger the final route change to bypass the entire building complex and speed past the stationary planes.

To get all the route changers in Dry Docks, draft and drift your way along the track and trigger the boat to have it collapse and open a route off to the left. Gather as much power as you can before triggering the cargo boat just after the start line. Continue to drift until you reach the boat you destroyed earlier. Trigger the route change again to have it shooting off down the dry dock and opening the final path.

The quickest way I found to grind this one is from the main menu select:

Quick Play -> Elimination -> Airport Terminal.

As soon as the race begins, tail the driver in front of you until you have a level 2 (red) powerplay. If done correctly by the time you reach the collapsible tower on your left you will be able to bring it down. As soon as it starts to fall slam your brakes on, putting yourself into 8th place therefore eliminating yourself seconds later.

Select restart, rinse and repeat.

Route changers are always level 2 power plays and those take time to build up. So a quick way to do it is just put yourself in 8th at the start of a race and get draft from everyone else. This should build up the meter quickly. Don't use power plays unless there's a shortcut or unless you know you can get it back quick enough. Since some stages don't have route changer, I suggest Airprort Terminal because I know it has three route changers.

EDIT: 1st is the tower that falls and puts you on the tarmac. 2nd is after the finish line which takes you underground. 3rd is after the finish line as well but this one takes you around the airport, through the shuttle area, and puts you back on the tarmac.

I would just also like to add that you can get this achievement out of the way while boosting for:



If you have time and don't want to idle for a couple hours, you can tell whoever's hosting (aka the person getting boosted) to set the map to Ferry Wharf. Then all you have to do is Draft behind the person hosting (or others not getting boosted yet but also driving) and Drift around corners and you will fill up your bar before the end of the first lap where there is a large cruise ship you can displace to change the route.

This gives you one route changer per game and I was even able to pull of 2 one time since there are 2 route changers in this map that can be triggered if you fill your bar fast enough. Doing this, you will have the achievement by the time your boosting session is over.