The seismic upheavals seem to be quieting in Sumatra, so I'm going to step back and write about a different sort of calamity: Jakarta traffic.
The concept of "lanes" is viewed as more of a suggestion than a rule here, and vehicles just pack in as close to each other as they can. This bajai (small three-wheeled vehicle) was maybe 4 inches from our bemo (slightly larger three-wheeled vehicle). Motorcycles constantly weave in and out, squeezing through any opening wide enough to fit them -- and sometimes openings that turn out not to be wide enough. I often wonder how long the average side-view mirror survives here.
On a two lane street, with one line of cars in each direction, there is a sort of "shadow" lane right down the middle that may be used for passing in either direction. Of course, if vehicles in both lanes are trying to use it at the same time, things can get a bit tense. Drivers here are pretty aware of what's going on around them, though, and they're generally willing to give way to each other. Plus the traffic is so jammed nobody can go very fast.
Some people say Jakarta traffic will reach total gridlock in 2014. Others maintain that this has already happened.