There are hundreds of preserved heritage railways around the globe sharing a common appeal to the sense of nostalgia that the age of steam stimulates. In comparison to their homogenised and characterless diesel and electric successors, steam engines are eulogised as living, breathing engineering marvels; their personality expressed through moving parts, beguiling puffs and whistles, the smell of coal and soaring plumes of smoke.
It is this nostalgia for the golden age of rail travel that has led to an overly romantic notion of how a real railway would have worked. Rather than a refined world of polished wood and gleaming brass, working steam trains offer a much more visceral experience - one of screeches, jolts and dust. Such realities can today only be found in a diminishing number of remote locations.
With the breathtaking expansion of its high-speed rail network (which will connect even Urumqi, in distant Xinjiang, this year) it is easy to forget how recently China emerged from the steam age. Production of its workhorse engine, the 130-ton QJ, only ceased in 1988 and the last steam-hauled main-line service, in Inner Mongolia, ran until 2005. These huge engines, designed in the 1950s, were still in service after the launch of the 431km/h Shanghai Maglev.
In view of recent developments it is remarkable that only two hours from Chengdu - the vibrant capital of Sichuan province whose rapid development, fuelled by the "Open Up the West" programme, has been spectacular even in Chinese terms - a genuine steam-powered railway has survived, unadulterated and with a plausible claim to be the last in the world to still offer passenger services.
Constructed in 1958, the narrow-gauge Jiayang Railway connects the towns of Bagou and Shixi, in Qianwei county. Although primarily built to transport coal, the line proved so popular with locals looking to hitch a ride that a dedicated passenger service was introduced in 1978.
Trains still trundle through 20 kilometres of Sichuan Basin mist, passing villages and bamboo plantations en route to Bagou, a town without a connecting road until 2012 and a destination that has remained essentially untouched by the economic changes of the past 35 years.
Bagou's population fell from 20,000 to less than 1,500 when its coal mine closed, leaving hospitals, schools and miners' cottages abandoned. These buildings have fallen into a state of abject disrepair, vividly highlighting how a devastating decline can leave a town and its residents unquestionably worse-off today than they were 50 years ago - a curious and unfortunate position in modern China.
This isolation may now, finally, be working to Bagou's advantage as a small but growing number of tourists, typically urban Sichuanese, come to Qianwei county to ride on the train and marvel at the fact that the town has survived as it has into the 21st century. Guesthouse owners report increasing bookings and, when one considers the boom in domestic tourism, increased car ownership and the fact that there are very few places where it is possible to experience something approximating China's nearly erased but not-so-distant past, further development looks highly likely.
The local government evidently recognises that nostalgia and interest in the industrial past can be a draw for tourists and has supported work to promote the rail line, signposting it regionally as "a living fossil of the Industrial Revolution". With further support from European rail enthusiasts and investment from the line owners, the Jiayang Mining Company, it is now transitioning from a "real" railway to a heritage one.
The most visible change has been the addition of air-conditioned tourist services. These have tour guides aboard and offer a stop at the most scenic spot en route: the Jiaoba Curve. Here passengers disembark to photograph their train reverse and then shriek past at full steam and top speed: 30km/h.
Local services have not been significantly affected and a regular schedule still operates. For five yuan (HK$6.40) it is possible to ride the line in its entirety, though seats are not guaranteed if embarking at an intermediate station and carriages can be crowded. One-way tickets on the new tourist services cost 50 yuan.
All trains are powered by one of six steam engines. Built in Shijiazhuang, Hebei province, in the 1950s and 60s, they are housed and serviced in Shixi. Rusting, patched-up and temperamental, they offer a stark contrast to the gleaming, polished and painted examples beloved by operators of conventional heritage railways.
Most passengers, both locals and tourists, disembark in Bagou but it is possible to carry on another kilometre, to the village of Huangcun. The buildings here are adorned with spectacular - touched-up but otherwise authentic - Cultural Revolution-era slogans and artwork imploring residents to be "resolute in their political direction" and to "always be guided by Marxism-Leninism".
Huangcun is also home to the coalmine Bagou relied on for more than 70 years. This was converted into a tourist attraction in 2008 and guides, all daughters of miners, lead enlightening tours.
From Huangcun, the 20-minute walk to Bagou through plantain groves (Bagou's full name, Bajiaogou, means "plantain ravine") passes a deserted occupational disease clinic, hospital and middle school, all of which, for now, can be explored freely. Back in town the most interesting buildings are the British-built miners' cottages that date back to the Sino-British mine, which was established in 1938, during the second Sino-Japanese war. Many of the cottages are close to collapse - including the few that remain occupied.
The star attraction for those looking for relics of the Cultural Revolution is the Workers' Theatre, a 1,040-seat venue that once hosted performances of revolutionary plays and films. Here, stacked up in a corner, are a number of large portraits of Mao Zedong, Zhou Enlai, Hua Guofeng and Sun Yat-sen. The affable superintendent, Mr Li, takes great pleasure knowing that his occasional visitors find these of interest, yet, despite living in the theatre with his family and being paid to do what he can to prevent further deterioration, he has been given no information about when, or if, it will ever be restored.
Renovation has, however, been completed on the adjacent Mao Stage, where 40 years ago supposed class enemies were viciously humiliated in "struggle sessions". Today, the Great Helmsman watches over nothing more seditious than the popular evening guangchangwu ("square dancing") sessions.
Will Bagou and the Jiayang Railway maintain their authenticity in the face of heightened pressure to redevelop and commercialise as tourist numbers increase? For now, the transition to a heritage railway is being undertaken with consideration for the locals who still rely on its services. If such sympathetic development can be maintained then the town and railway could serve as a model for other heritage-themed attractions in the mainland.
For the time being, though, the adventurous still have the opportunity to travel back in time and get a sense of what life was like in small-town China a mere generation ago.
Getting there: Dragonair and Hong Kong Airlines both fly directly from Hong Kong to Chengdu. Buses run every hour from Chengdu's Shiyang bus station to Qianwei and the journey takes two to three hours. Once in Qianwei take a local bus, taxi or motorbike taxi to either Shixi - the true beginning of the line - or Yuejin, where the tourist trains commence. It is possible to hike the full length of the line and attendants are on hand to say when it is safe to pass through each of the six tunnels. Accommodation is available en route, but is easiest to find in Bagou.