LEGO Batman

This achievement is buggy but an easily preventable bug, there is something that stops it from popping which is destroying the 2 traffic lights in the level.
If you have previously broken a traffic light clear your consoles cache from the 'storage' menu in settings.

So to be clear on the first Hero level you are required to destroy all 21 streetlights but NO traffic lights.

There are 2 traffic lights in the level they must remain intact for the achievement to pop.

Here's a video walkthrough, In it i use an extra and also do it in story mode. Just to confirm there are no bugs related to those.

This isnt the first time ive done this method, ive tried on many accounts and this was the only way to unlock the achievement.

This achievement is known to bug alot. It actually bugged for me and I even tried the batarang tactic, tried playing on free play and on replay story but nothing seemed to make it unlock.

What I did was I started a new game, played level 1 broke the street lights and the achievement unlocked, then just go back to dashboard without saving and you can keep playing your game and the achievement is yours.

If your achievement is glitching like mine did turn off ALL the extras go into story mode and only use the bat-a-rang to destroy the light posts.

This achievement is much harder than it needs to be because of bugs and unlisted requirements but after 7 or 8 tries I got it and wanted to share what worked for me. There are 21 light posts in level 1-1. Breaking all of them still may not trigger the achievement, here are some of the precautions I took and it worked:

When this achievement popped, there were actually 2 light posts left so the counter has an issue.

1) I did this on story mode, single player. ( with a saved game that had most of the hero levels complete but none of the villain ones done. I don't think this last part matters though, just pointing out this was not a new save and I definitely broke the traffic lights in other attempts)
2) I reset my Xbox, loaded up Lego Batman, and went right to level 1-1 in story mode.
3) I broke 2 light posts with Batman but one was by knocking a goon into it, so I quit the level and went to the Batcave. ( I did not save progress)
4) I immediately went back to story mode for level 1-1. Then I played the level only as Batman and never switched to Robin.
5) I did not break the traffic lights.
6) I had no extras on. (don't actually have any unlocked)
7) I also broke the green upside down bell-shaped objects right at the beginning. Not sure if that matters but some people have claimed it did.
8) I did use fists sometimes but mostly used the bat-a-rang on the light posts.
9) I died once by falling off an edge so that doesn't seem to matter.
10) I didn't finish the level. The achievement pops right away.

If you don't get the achievement by the time you get to the part where you must switch to Robin to progress, exit to the Batcave and don't save. Since the achievement popped for me with two light posts still on the screen, I am guessing that as long as you don't switch off from Batman you may be able to break a few, exit to the Batcave and come back and have it still count them. I'll try to confirm this later today with another account.

destroy all 21 street lights (lamp posts) in Episode 1 Chapter 1. also do not destroy the Traffic Lights or it will cause the achievement to Not Trigger (thanks to Spilner for this info.)

these are the red/orange lights sitting on the grey poles with the blue/green base and top. the traffic lights to avoid destroying are not the realistic looking ones, but the lego ones that look very similar to the street lights. they have a red and a green lego stud on top. you do not have to complete the level, the achievement should unlock after destroying the last light.

==locations==
1: (easy to miss) from level start, go left. there is one in the bottom corner by the gate.
2-5: along the first "city block" right on the street.
6: climb up and over the chemical spill, it's behind the damaged leaking truck.

AVOID: traffic light right after #6, on the street corner.

7-9: in the side street that goes back to a dead end with a dumpster and riddler box, just after the chemical spill.
10: below the second "realistic" traffic light, right where the street is all torn up.
11: right next to the cement truck that you must use explosives to get past.
12: right after #11 on the next street corner.

AVOID: traffic light right after #12, on the opposite corner of the block.

13: in the far right corner of the level, right after the long truck filled with silver objects.
14: after passing the truck and moving to the next section of the level, just before the two riddler boxes.
15: when the street starts to go downhill, stay above on the sidewalk, right after the same two riddler boxes.
16-21: they are all located together, surrounding the 4 tall green bushes / trees.

It worked for me when I did the first level without selecting a storage device and following the first guide