The rumble of traffic on the Interstate-40 Mississippi River bridge in Memphis has been replaced by staccato bursts of drills and bolt tensioners as workers with Kiewit Infrastructure Group race to stabilize a fractured tie girder that forced an indefinite closure of the key Tennessee-Arkansas crossing on May 11.
开始于5月21日开始的24小时努力是田纳西州运输部（TDOT）进行的两阶段维修策略的第一部分。它与阿肯色州运输部（ARDOT）共同承担维护职责。从河上方的两个900英尺长的绑扎式河流中的一个悬挂的100英尺平台工作，横跨河上约110英尺，乘员乘以24 x 32英寸的钢制钢板增加了33,000磅的钢板。Tie-Girder的1.375英寸厚的顶部和底部部分，以及.5英寸厚的侧面部分。
“From a repair standpoint, the first thing was to look at the bridge and see if it’s safe for traffic underneath,” as well as for repair crews, says Paul Degges, TDOT deputy commissioner and chief engineer. Workers are bolstering the girder with a 54-ft-long, 2.5-in.-thick outer plate and a slightly shorter inner plate. The plates will restore sufficient stability for the arch to support heavy equipment necessary for second-phase repairs, which may include installation of high-strength steel rods so that the 37-ft-long section can be replaced.
没有宣布维修费用或时间表，这些维修是根据TDOT的紧急签约机构进行的。Degges说：“我们正在新的盒子梁上完成设计。”“至少需要六到八周的时间，但是我们希望一旦完成图纸，我们就可以巩固时间表。”
Ardot的检验顾问Michael Baker International（MBI）在对近50年历史的过境点的常规调查中提醒该机构骨折。MBI是来自TDOT，ARDOT和KIEWIT基础架构组的输入的记录工程师。
剩下的要确定的是骨折的起源，阿多特说这可能是数十年来恒定交通而不是船舶撞击或与天气有关的原因导致的“疲劳类型”断裂。对桥梁的紧急检查没有发现其他结构问题。
未报告
关于未报告骨折的现已终止的ARDOT检查员的详细信息。
Monty Frazier, a 15-year ARDOT employee, was team leader and under-bridge inspection unit operator for the annual fracture-critical inspections conducted in September 2019 and 2020. Frazier reported no issues with the continuous welded beams that form the structure’s 110-ft-high navigation spans, but drone video from a May 2019 inspection by MBI indicated the break had begun to form.
By the time ARDOT officials were alerted on May 11, the tie-girder’s upper and outer flanges had separated, while the bottom flange was approximately 50% cracked. The bridge, which has about 41,000 daily crossings, was immediately closed.
According to ARDOT documents released through a public records request by the Hot Springs, Ark., Village Voice newspaper, Frazier told Michael Hall, the agency’s heavy bridge maintenance engineer, that it was “unsafe” to move the under-bridge inspection unit along the outside of the tie girder.
霍尔在5月14日的终止备忘录中驳斥了弗雷泽（Frazier）的主张，并指出：“标准练习是沿着领带梁蓬勃发展，寻找裂缝。”他还指出，当另一名雇员控制桥下部门时，弗雷泽（Frazier）自己就做了这一点，该单元配备了“安全功能，使人无法进入不稳定的位置”。
ARDOT announced the termination May 17 without mentioning Frazier by name, stating that “the employee failed to carry out his responsibility correctly,” and could possibly face criminal charges. ARDOT is reviewing inspections led by Frazier of at least nine other bridges, as well as its inspection practices.
