Main Page
Welcome to the explain xkcd wiki!
We have an explanation for all 3183 xkcd comics, and only 51 (1.6%) are incomplete. Help us finish them!
Latest comic
| Bridge Clearance |
 Title text: A lot of the highway department's budget goes to adjusting the sign whenever the moon passes directly overhead. |
Explanation
Bridges will often have signs indicating the height of the bridge, primarily to indicate to taller vehicles the potential hazard of driving under them. In this comic, there is a bridge with one of these signs, indicating a clearance of 10 feet and 6 inches, which is a normal clearance for a bridge to have. To its right, there's a sign which says "no bridge", indicating a clearance of 46 billion light years. This sign indicates a clearance approximately equal to the radius of the observable universe. This is because there isn't any bridge.
The title text references the fact that when the moon passes over the sign, the clearance would be reduced to the distance between Earth and the moon, as any vehicle driving there would need to be shorter, otherwise it would crash into the moon. Both of these signs ignore the fact that vehicles cannot be large enough that either of these clearances would be something necessary to account for while driving.
The title text says that the sign might crash into the moon during certain times. However, they also need to adjust it for any stars, which would be easier if their were just people living on the sign and adjusting it with some smart mechanism.
Transcript
[:There is a road with a fork and one side that goes to the left has a sign. The one that goes forward has a bridge and a clearance sign.]
[:left sign with bridge underlined, it has a horizontal line that is dotted with slashes.]
Bridge
Clearance
10 ft 6 in
[:right sign with No bridge underlined]
No Bridge
Clearance
46+ Billion light years
View comic discussionNew here?
Last 7 days (Top 10) |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
You can read a brief introduction about this wiki at explain xkcd. Feel free to create an account and contribute to the wiki! We need explanations for xkcd comics, characters, What If? articles, and everything in between. If it is referenced in an xkcd comic, it should be here.
- If you're new to wiki editing, see the explain xkcd:Editor FAQ for a specific guidance to this wiki and the more general help on how to edit wiki pages. There's also a handy wikicode cheatsheet.
- Discussion about the wiki itself happens at the Community portal.
- You can browse the comics from the list of all comics or by navigating the category tree at Category:Comics.
- The incomplete explanations are listed here. Feel free to help out by expanding them!
Rules
Don't be a jerk!
There are a lot of comics that don't have set-in-stone explanations; feel free to put multiple interpretations in the wiki page for each comic.
If you want to talk about a specific comic, use its discussion page.
Please only submit material directly related to xkcd and, of course, only submit material that can legally be posted and freely edited. Off-topic or other inappropriate content is subject to removal or modification at admin discretion, and users who repeatedly post such content will be blocked.
If you need assistance from an admin, post a message to the Admin requests board.
