So, I got home after work tonight...
Riding home, I was sort of dithering over whether to use the expressway under Yamate-Dori to get home. I noticed the pixelboard over the Tomigaya entrance saying 西池袋から渋滞 which means “Traffic jam from Nishi-Ikebukuro”. It also observed that the traffic jam was 1km long, which is pretty long, but nothing I couldn’t deal with. Just on a hunch, because I’m familiar with that stretch of road and how traffic jams build up on it, I decided that I’d not go onto the expressway there and that I’d keep going to the next entrance, to see what the conditions were like.
The next entrance, Nakano Chojabashi, had amended the congestion notice: 中野長者橋から渋滞５ｋｍ. Which meant that the traffic jam started right there and went on for 5km. Under it, there was another, much more ominous note: 自動二輪者死亡事故発生. Motorcycle fatality.
Not only did I not take the expressway home, but I was riding noticeably slower and more carefully on the way.