Over the next twenty-five years, six independent deep underground lines were constructed.

在接下来的25年里，又建造了6条独立的地下线路。

The underground line affected is old and has experienced many problems in recent years.

受影响的地铁线路老旧，近年来出现了许多问题。

They think they might have to do with the leak in underground natural gas line.

他们认为可能与地下天然气管道泄漏有关。

It's a story that begins over 150 years ago in 1863, when the world's first underground line opened, the Metropolitan Railway.

这要从 150 多年前的 1863 年开始说起，那年，大都会铁路开通了世界上第一条地铁。

So, they tried something that was relatively  new and innovative for the time: they ran the line underground.

因此，他们尝试了当时相对较新和创新的做法：将线路运行在地下。

The explosion at 7: 30 a.m. closed the nation's busiest bus station, eight underground train lines and all the streets around Times Square.

事发时间为早上7点30分，地点位于全国最繁忙的公交站、8条地铁线路和时代广场街道的附近。

As you might know, many materials expand or contract with changes  in temperature, and that's true for the copper conductors used in underground transmission lines.

您可能知道， 许多材料会随着温度的变化而膨胀或收缩，对于地下传输线路中使用的铜导体来说也是如此。

He learned that a high voltage underground  transmission line had experienced a fault, costing the City tens of thousands of dollars  per hour in lost capacity and downtime.

他了解到一条高压地下输电线路出现故障，导致该市每小时因容量损失和停机而损失数万美元。

The Metropolitan reports show that they spent anywhere from $500,000 to $600,000 a mile building underground trolley lines which, at their own extravagant estimate, should have cost only $150,000.

他们每英里花费 500,000 美元到 600,000 美元建造地下有轨电车线路， 根据他们自己的奢侈估计， 这些线路的成本应该仅为 150,000 美元。