無人駕駛汽車的優點之一，就是據說它比有人駕駛汽車要更安全。根據全美公路交通安全管理局的統計，在所有車禍中，有高達94%的比例是由人為失誤導致的，這些人為失誤包括酒駕、超速、分心和疲勞駕駛等。

不過近日的一份研究報告顯示，無人駕駛汽車不論進行多少小時的測試，都不足以確定其安全性。

該報告來自美國著名智庫蘭德公司。報告稱，無人駕駛汽車恐怕需要經過“幾億甚至幾千億英里的路試”，才能獲得足夠的信息來比較出它與有人駕駛汽車二者哪個安全系數更高。這樣徹底的測試可能需要“幾十年甚至幾百年的時間”。要想在交付消費者正常使用前完成如此巨量的測試任務，顯然是不切實際的。

根據來自美國交通部的數據顯示，2013年，美國有229萬人在車禍中受傷，32,028人因車禍死亡。這些數字雖然觸目驚心，卻是建立在美國人民每年要合計駕車行駛3萬億英里的基礎上的。

這份研究報告的聯合撰稿人、蘭德公司的高級統計學家蘇珊?帕多克在公司的一份聲明中表示：“在研發無人駕駛技術的公司中，最長記錄在案的路試里程是130萬英里，光是如此也耗費了好幾年的時間。即便無人駕駛汽車進行了1000萬英里的路試，我們也無法對它的安全性和可靠性給出統計學意義上的結論。”

蘭德公司的研究人員還指出，無人駕駛行業有必要開發其它的測試方法，以檢驗無人駕駛汽車是否真的比有人駕駛汽車安全。

據谷歌公司披露，該公司的無人駕駛汽車項目啟動以來，其測試車輛已經出過大大小小十余次事故。不過谷歌還表示，所有事故都是由人為因素導致的。（但是截止到目前，谷歌測試車上的真人駕駛員也成功避免了13次事故的發生。）話雖如此，但從密歇根大學交通研究所的研究人員布蘭登?舒特勒和邁克爾?席瓦克提供的數據來看，無人駕駛汽車發生事故的機率高達有人駕駛汽車的五倍。他們還發現，同樣在發生交通事故時，無人駕駛汽車的成員受傷的人數要高于傳統汽車，但目前尚無無人駕駛汽車導致乘員死亡的報告。

舒特勒和席瓦克的這份分析報告發布于2015年10月，所用的數據部分來自加州有關部門的公開數據，但更多的數據還是來自谷歌。他們將有關事故數據與2013年的全美道路交通安全記錄進行了對比。研究人員指出，各大無人駕駛技術公司所記錄的路試里程與傳統的有人駕駛汽車相比，還是很低的。

從現有事故報告來看，在任何一起事故中，無人駕駛汽車都不是主要過錯方。它們往往是在停車或者在車流中緩慢移動時被其他車輛撞擊，最頻繁的事故就是被追尾。

另外，隨著技術的持續突飛猛進，將來與無人駕駛汽車有關的事故數量也可能會進一步下降。（財富中文網）

譯者：樸成奎

One of the arguments for self-driving cars is thatthey will be safer than human-driven vehicles.Human error is the cause of 94% of car crashes, according to the National Highway Traffic Safety Administration. Those errors include drunk driving, speeding, distraction, and fatigue.

But a new report finds that self-driving cars can’t be tested enough hours to determine their safety.

Thereport from research firm RAND Corporation says autonomous vehicles would need to be tested “hundreds of millions of miles and sometimes hundreds of billions of miles” to gain enough information to compare its safety to human-driven automobiles. Such thorough testing would require “tens and sometimes hundreds of years,” which would make it impractical to accomplish before clearing the vehicles for regular consumer use, the report said.

According to the U.S. Department of Transportation, there were 2.29 million auto-related injuries and 32,028 fatalities on the highways in 2013. However, those numbers come in the context of the 3 trillion total miles driven annually in the U.S.

“The most autonomous miles any developer has logged are about 1.3 million, and that took several years,” study co-author and RAND senior statistician Susan Paddock said in a company statement. “Even if autonomous vehicle fleets are driven 10 million miles, one still would not be able to draw statistical conclusions about safety and reliability.”

The RAND researchers say that industry needs to develop other ways to examine whether self-driving vehicles are safer than those piloted by humans.

Google has said there have been more than a dozen accidents with its self-driving cars since the self-driving car project began. But it has said all of those were caused by humans. (However, human drivers have prevented the autonomous vehicles fromcausing an accident 13 times so far.)

Still, data from researchers Brandon Schoettle and Michael Sivak from the University of Michigan Transportation Research Institute found that self-driving vehicles have been nearly five times as likely to get into accidents as those driven by humans. They also saw somewhat elevated numbers of injuries per crash compared to normal traffic but no fatalities.

Schoettle and Sivak based their October 2015 analysis on available data from California as well as more extensive data from Google. They then compared the number of accidents to 2013 national safety records. The researchers noted that the amount of recorded miles was low compared to conventional traffic.

The automated cars weren’t at fault in any of the crashes. Instead, they were struck when stopped or moving slowly in traffic and most frequently were rear-ended.

Also, as the technology continues to advance rapidly, improvements might help reduce the number of accidents involving self-driving cars going forward.