This episode is for all you (us) traffic nerds--we're talking about the hidden structure underlying traffic on-ramp metering systems. These systems slow down the flow of traffic onto highways so that the highways don't get overloaded with cars and clog up. If you're someone who listens to podcasts while commuting, and especially if your area has on-ramp metering, you'll never look at highway access control the same way again (yeah, we know this is super nerdy; it's also super awesome).
Relevant links:
http://its.berkeley.edu/sites/default/files/publications/UCB/99/PWP/UCB-ITS-PWP-99-19.pdf
http://www.its.uci.edu/~lchu/ramp/Final_report_mou3013.pdf