• Turing tells you that you'll have to think ahead
  
• You don't have to change the signals where the taxi currently is, any intersection on the map can be changed
  
• It's best that you keep the taxi away from the west side of the map, the diagonal streets will screw you over

If you screw up, don't worry. Just exit back to the game's main menu and click "Continue". It'll send you back to the start of the puzzle

If you're still having trouble solving it, just follow these steps

1] Tell Turing to cut off the north part of the first intersection
2] In the bottom-far right intersection, cut off the bottom and right so the taxi travels north
3] In the middle-far right intersection, cut off the top and right so the taxi travels westward
4] In the middle-right intersection, cut off the bottom and left so the taxi travels north
5] In the middle-top intersection, cut off the top and right parts so the taxi travels to the south
6] Next go to the GOAL intersection cut off all four parts. Don't worry about the taxi since it will now arrive at the GOAL on its own
7] Cut off any untouched intersections to move the taxi, and you're done!

Here's what the map should look like when you're done:[i.imgur.com]