https://c8.alamy.com/comp/P68K3Y/180629-golmud-june-29-2018-xinhua-a-maintenance-worker-checks-the-tracks-at-the-xinguanjiao-tunnel-the-worlds-longest-plateau-rail-tunnel-along-the-qinghai-tibet-railway-in-northwest-chinas-qinghai-province-june-27-2018-with-a-length-of-326-kilometers-the-tunnel-was-put-into-operation-at-the-end-of-2014-xinhuahou-deqiangmcg-P68K3Y.jpg