outbound line

笹子トンネルで、事故がなかった側の車線に670箇所の不具合だそうです。数だけを見ても驚きです。

outbound laneについてです。outboundは外国行きという意味があるのはご存知かと思われます。「国境を越える」というが文字に現れていますね。５０州あるアメリカでは「《米》〈列車が〉州外行きの」（『ジーニアス英和辞典　第４版』大修館）という意味にもなりますね。
" moving away from you or away from a town, country "という定義がLDOCEにはあります。「外に出ていく」方の車線であるため、outbound lineは「下り車線」ですね。もちろん反意語はinboundです。念のため。(Minnesota)

Officials of Central Nippon Expressway Co (NEXCO), which operates the Sasago tunnel in Yamanashi Prefecture, where a fatal cave-in occurred on Dec 2, said Thursday that an emergency inspection of the tunnel’s outbound lane revealed defects in 670 locations.

After the accident in the inbound lane—in which nine people died—the government ordered NEXCO to inspect the Sasago and other tunnels, especially ceiling panels.

A NEXCO spokesman told a news conference that the bolts which fix the ceiling panels to the nearly 5-kilometer-long tunnel were loose or corroded in about 632 places, TV Asahi reported. In other parts of the tunnel, the concrete top of the tunnel was cracked. In all, the company said it had detected problems in 670 spots.

http://www.japantoday.com/category/national/view/defects-found-in-670-locations-in-sasago-tunnel