That seems like a loaded question and I’m not sure if you’re entirely correct. But I’ll take it for granted that China is “so ahead in infrastructure”.

这似乎是一个诱导性的问题，我不知道你的观点是否完全正确。但我对于中国“在基础设施上如此领先”这一看法是赞同的。

The reason is probably that the USA built most of its infrastructure a long time ago. Once it’s there there is little incentive to upgrade it. Why spend billions when you can make do with what you’ve got? Also once the capital stock of a country reaches equilibrium a large fraction of savings (pretty much all of it) is used up in maintaining existing capital.

原因可能是美国很久以前就建设了大部分的基础设施。一旦它已经存在，没有什么理由来升级它了。当你能用所拥有的东西来完成想做的事时，为什么还要额外花费数十亿美元呢？此外，一旦一个国家的资本存量达到均衡，大部分储蓄（几乎全部)都被用于维持现有资本。

Rewind to 1990 and China had very little infrastructure. As its economy has boomed it has accumulated capital very rapidly. Now it is at a point where there is too much capital. The government has used investment to employ some of the country’s excess capacity and support an ultimately unsustainable rate of growth. The problem is that the capital will not be able to be maintained. It would require an astronomical savings rate. China wants to transition to a consumption driven economy but how can it do this while simultaneously maintaining a high savings rate to support a huge capital stock?