A protective coating on a glass sightseeing box that extends from the 103rd floor of the Willis Tower in Chicago cracked Wednesday night, but officials said no one was ever in danger.

Tourist Alejandro Garibay and four of his family members were standing in one of the glass boxes that jut out from the side of the tower when they heard a strange, worrisome noise below them.

A Willis Tower spokesman Bill Utter clarified Thursday that it was a protective coating, not glass, that cracked -- as it sometimes does.

"At no time whatsoever was the integrity of the structure compromised," he said.

The ledges are designed to hold 5 tons, and the coating keeps the glass from being scratched.

"The protective layer did exactly what it was supposed to do," Utter said.

The four Skydeck ledges are a series of clear bays with glass floors that extend a little more than 4 feet from the building. Visitors can see the street 1,353 feet below their feet. According to the Skydeck website, each bay is made from three layers of half-inch thick glass.

Visitors who step into one of the boxes can see for 50 miles across four states.
Since 2009, 6 million people have ventured into the ledges, which retract into the tower when the windows need cleaning.

The ledges were closed for some time Thursday, but the Skydeck viewing area on the 103rd floor was open.

Around 7 p.m., Willis Tower's Facebook page indicated that "the new protective coating on Ledge 4 has been installed."

"Skydeck Chicago is open, including the other three unaffected Ledges, and Ledge 4 will be back open tomorrow," the post added alongside photos of workers at the scene.

The Hancock Building nearby has a new glass observation feature, but visitors hold on to handrails as the section tilts out about 1,000 feet above the city streets.

【新聞快訊】

位于美國芝加哥的威利斯大廈是全美第二高樓(世界第八)。在大廈的頂層有四個觀景室，地板是用透明玻璃構(gòu)成的，可以從里面對芝加哥進(jìn)行全方位的觀景。然而29日，其中一個觀景室的地面玻璃開裂，讓當(dāng)時站在上面的游客驚出一身冷汗。

當(dāng)時，阿萊揚德羅跟其他三個親戚正在參觀芝加哥的這座摩天大樓并坐在觀景臺拍照，突然間，他們屁股下面的玻璃開裂了，發(fā)出了一陣陣破裂的聲音。要知道，他們當(dāng)時可是在400多米的高度，萬一玻璃全碎了，后果不堪設(shè)想。

“我的手放在了地面上，我能感受到它正在開裂?！卑⑷R揚德羅說，“說實話，我真是嚇壞了?！敝S刺的是，游客在走上玻璃觀景臺之前，工作人員會告知他們地面的玻璃可以承受5噸的重量，是牢不可破的。

第二天早晨，樓上的四個觀光臺都被關(guān)閉進(jìn)行例行檢查，并更換了破損的部分。

該大樓發(fā)言人表示，破裂只是玻璃的表層，玻璃本身仍安全。發(fā)言人也說，這破碎情況不尋常，但以前曾發(fā)生過。

據(jù)報道，威利斯大廈樓高442.3米，共地上108層，地下3層，1974年落成，當(dāng)時還是全球最高大樓。

威利斯大廈在2009年新增觀景臺，它于103樓外墻增加四個玻璃觀景室，全以強(qiáng)化玻璃打造，可讓民眾踏出樓外約1.3米。

而此次玻璃碎裂事件正是這凌空于幾百米高空的觀景臺地板玻璃碎裂，真是讓人心驚膽顫啊。