甘肅鐵堂峽隧道左洞長6051米，右洞長6048米，是十天高速公路全線最長隧道。中交二公局承建了8508米（左洞長4251 米，右洞長4257米）隧道主洞及斜井施工任務(wù)。該隧道穿過山體以板巖、粉砂質(zhì)板巖、砂巖為主，施工中攻克了節(jié)理裂隙發(fā)育，巖體破碎，圍巖穩(wěn)定性差，易滑塌變形等難題。
　　Gansu Tietangxia Tunnel, with the length of left hole of 6051m and length of right hole of 6048m, is the longest tunnel of Shiyan-Tianshui Expressway section. CCCC Second Highway Engineering Co., Ltd. has contracted to construct the main tunnel hole with 8508 m long (left hole with length of 4251m and right hole with length of 4257m) and the inclined shaft construction work. The tunnel, through the mountain, is mainly composed of slate, silty slate and sandstone, Many problems were overcome such as the problems of joint crack development, rock mass breaking, poor stability of surrounding rock and easy sliding deformation in construction.