First of all, this particular line was not originally built as a so-called "high speed rail" line; being designed for 160kmh max. Speeds like this were enjoyed in America in some places at the dawn of the streamliner era, with just block signals in most cases.

Of course later on, that was changed with the imposition of the federal 79mph limit, unless cab signaling and ATC or ATS was present and in use. But even so, most places with cab signals still used the wayside signal as well, the position of which still controlled the cab codes in the rails (since changed). A few Pennsy lines did without the wayside signals, relying solely on the cab signal, except near interlockings, but that was an exception.

Even now, the Amtrak's Acela operates at a top speed of 240kmh over trackage with wayside signals. The first French TGV to Lyon was build with American train control technology (GRS to be precise), and did use wayside home signals and approach signals at interlocked switches. Wayside block signals were not used on the TGV. Of course, both of these systems use cab signaling coded through the rails, backed up by an ATP system that enforces compliance by utilizing "Braking supervision". This is every bit as secure and reliable as anybodies so-called PTS, or ETMS, or whatever, will ever be.

Two weaknesses in signaling design philosophies were exposed by this accident ---

First and foremost - no mechanical signal (semaphore, searchlight, etc) should be solely relied upon to control cab codes, as any injury to the signal can then cause a false code to be transmitted down the rails. This sort of design was done away with in the United states in 1953; but maybe not in China. Here, control logic directly controls the cab code and the signal, with the signal being cross checked for compliance before the cab code is sent.

Second - Operating speeds cannot just be bumped up willy-nilly just because you bought a fancy faster train; as appears to have happened on many lines in China. The train control system must first be seriously re-arranged to provide proper braking distances at the higher speeds. This is a difficult and very expensive process, and is rife with political temptations to cut corners, even in the U.S..

That of course is especially problematic when you are talking about countries that routinely execute dissenters, Yes I know: there are cutthroat corporate leaders that will fire you for the same - but at least you ain't dead. As we have seen ever since Clinton declared them "Most Favored Nation", we have been treated by the Chinese to one cutthroat corner cutting fiasco after another, with sometimes disastrous results. Apparently, they also have no regard for their own citizens either - also with disastrous results.

They simply cannot be trusted when our welfare and safety is at stake, And neither can whichever American politician, governor, CHSRA director, or whomever; that permits the Chinese one more inch on our American soil!

Same goes as well for stuff from certain Western European countries, who also have demonstrated a low regard for public safety (the ones with a relatively short history of non-authoritarian government).