tunnel
... that due to receding glaciers, in 1951, the Alaska Railroad was able to move its route and abandon a curved tunnel built in 1906?
... that due to receding <a href="./Glacier" id="mwCNo" rel="mw:WikiLink" title="Glacier">glaciers</a>, in 1951, the <a href="./Alaska_Railroad" id="mwCNs" rel="mw:WikiLink" title="Alaska Railroad">Alaska Railroad</a> was able to move its route and abandon a curved <b id="mwCNw"><a href="./Alaska_Central_Railroad_Tunnel_No._1" id="mwCN0" rel="mw:WikiLink" title="Alaska Central Railroad Tunnel No. 1">tunnel</a></b> built in 1906?