China has the world's longest HSR network with over 19,000 km (12,000 mi) of track in service as of January 2014, which is more than the rest of the world's high-speed rail tracks combined, and a network length of 30,000 km (19,000 mi) is planned for 2020.
Since HSR started in China on April 18, 2007, DAILY ridership has grown from 237,000 to 2.49 million in 2014, the most heavily used in the world.
The nationwide HSR network extends to 28 of the country's 33 provinces and regions.

Nearly all high-speed rail lines and rolling stock are owned and operated by the China Railway Corporation, the state enterprise formerly known as the Railway Ministry.

Over the past decade, the country has undergone an HSR building boom with generous funding from the Chinese government's economic stimulus program. The pace of high-speed rail expansion slowed for a period in 2011 after the removal of Chinese Railways Minister Liu Zhijun for corruption and a fatal high-speed railway accident near Wenzhou, but has since rebounded. Concerns about HSR safety, high ticket prices, low ridership, financial sustainability of high-speed rail projects and environmental impact have drawn greater scrutiny from the Chinese press.
The fastest trains can reach operational speeds of up to 380 km/h (240 mph).

During my 2013-2015 stay in mainland China, I had to go to Hong Kong several times with my family for visa renewals, etc. so we got to experience that place as a first time visitor to the area... How did the ability to get around the place work for us, for instance.    And for me particularly as a Traffic Engineer from America, what was the transportation state of the art in China in one of their largest and diverse cities?