Seriously, it’s the worst possible place for an accident.

Here’s the situation. 3 lanes comprise 520-W. The rightmost is the carpool lane. 520 crosses a bridge, at the end of which the carpool lane becomes an exit lane for the interchange with 405. Then an on-ramp comes up from the right, which has a carpool lane on the left and a normal car lane on the right (2-lane on ramp). Those merge into one lane, which comes up next to the aforementioned 520 carpool lane-turned-exit lane. Now there are 2 normal lanes, then 2 exit lanes. The rightmost exit lane is 405-N, and the next inward is 405-S.

Seems vaguely reasonable. But then consider the traffic patterns.
First, you have carpool people barreling down the right-hand carpool lane of 520. Now that lane becomes an exit lane for *everyone* going to 405. So all of a sudden a quarter of the highway merges into the carpool lane.
Next, from the right, you have ordinary traffic, most of which is not interested in 405, because they want to take the 520 bridge over to Seattle. So all of these people need to cross from the right through the over-stuffed carpool/exit lane to get to the left.
Plus, all the people in the carpool/exit lane that want 405-N (me) are trying to merge farther right *into* the on-ramp traffic.

Now throw in rush-hour traffic in Puget Sound, and you’re looking at a grim interchange.

Then, for the icing on the cake, toss in a weekly accident complete with 2 cops, a tow truck, and 4 lanes of gawking idiots.

…

Estimated transit time from Microsoft Building 28 to The Park @ Forbes Creek:
   with no traffic: 15 minutes.
   rush hour traffic: 35 minutes.
   minor accident + 4 lanes of gawking idiots: 1 hour 5 minutes.

Why oh why do they all have to break down right there!?