Thirteen people were killed and 145 injured on Aug. 1, 2007, when most of the 41-year-old bridge fell into the Mississippi River.

NTSB在董事会批准的可能原因发现中还引用了贡献因素，包括桥梁设计师，Sverdrup＆Parcel and Associates Inc.的质量保证程序的失败，以确保计算Gusset Plates的计算。在桥梁的主桁架上，也完成了联邦和州运输机构的“设计审查不足”。

董事会说，另一个促成因素是联邦和州运输官员的“公认实践”，即在检查过程中不充分关注毛板，还排除了负荷分析中的板块。

Sverdrup & Parcel was later acquired by Jacobs Engineering. Jacobs spokespersons couldn't immediately be reached for comment after the board's meeting.

NTSB在其仍在发布的报告的摘要中说，失败的木板是在U（对于上）的10个钢桁架节点。这些盘子大约是一半厚，但国家设计标准要求它们的厚度为一英寸。NTSB说，八个主要桁架节点的八个盘子尺寸过大。

Along with the probable cause, NTSB approved nine recommendations for safety improvement to the Federal Highway Administration and American Association of State Highway and Transportation Officials, including some that would require federal and state agencies to pay greater attention to gusset plates in activities such as bridge inspection.

NTSB还建议FHWA和AASHTO开发桥梁设计质量保证/质量控制计划。

此外，NTSB建议AASHTO修改其桥梁评估手册，以增加对新桥进行负载等级的指南，然后才能开放交通并制定国家点的规格，以确保桥梁上的大量建筑材料不超载结构。

NTSB的代理主席马克·罗森克（Mark Rosenker）在为期两天的会议结束后告诉记者：“我认为我们对[FHWA和AASHTO]所做的技术'recs'将很久以防止这种事故发生再次。”罗森克（Rosenker）补充说：“现在已经认识到了对角板板的意义及其适当的设计的敏感性。”

Tom Sorel, commissioner of the Minnesota DOT, who attended the NTSB session, told reporters, "As we've said all along, this is the report that we've all been waiting for. This is, in our minds, the definitive report. Now we'll take the results of the report and digest them and respond."

Sorel added, "We feel we have a strong responsibility to implement any recommendations that we've been provided with our bridge program and we'll take this very seriously. We won't wait for any national standards or national guidelines. We're going to move forward in Minnesota to implement the right standards, the right guidelines."

美国事件迅速回应了董事会的建议。运输部长玛丽·彼得斯（Mary E. Peters）发表声明，宣布她指示FHWA与各州合作，以改善桥梁设计期间的质量控制。

彼得斯还指示FHWA修改其培训手册和检查程序，包括在所有适当检查中审查毛刺板的具体指南。

彼得斯说：“ [NTSB]的最终报告应该有助于关闭那些在那个命运的日子里失去家人和朋友的人的痛苦章节。”

董事会发言人说，NTSB调查的一些材料可在www.ntsb.gov上获得，但完整的报告将在几周内可用。