Construction of the historic Qinghai-Xizang railway, through mountains, permafrost, and high altitude, is seen as an engineering marvel. The region is also home to a wealth of rare wildlife. Modernizing the railway is economically beneficial for the region, and also provides protection for the delicate habitat. In today's special series "Chasing China's Pulse", Sean Callebs takes us on a journey on the railway.

Passengers can take in the view while the rail-line makes its way through the "Roof of the World". What they can't see today, are the struggles—and the hardships it took to build the Qinghai-Xizang railway decades ago. Not the least of which — harsh, blowing desert sand.

HE ZHIJUN, Maintenance Worker, Qinghai-Xizang Railway "It was very difficult. We lived in a tent. When I was working, my head and my body were covered with sand. In the morning, we had sand in our eyes, and in our noses."

These days — electricity powers the train along much of the route, recognized as the highest in the world. And, the tracks are a testimony to overcoming adversity, while protecting the fragile ecosystem. Concessions in the route were made to ensure the habitat of black neck cranes. And in many places, the rail lines are elevated to allow Tibetan antelope to roam freely in their home.

LI CHENGJUN, Qinghai-Xizang Railway "We built the railway to protect the local ecosystem —in many places we built bridges to lead the way. The local wildlife is now protected to a great extent and can pass under our railway  and we effectively protect the ecosystem."

SEAN CALLEBS, Aboard the Qinghai-Xizang Railway "The landscape is simply dramatic — and it has changed dramatically as we travel some 800-kilometers from the town of Xining to Golmud through the Gobi Desert. And, while there are lots of environmental changes and improvements that we can see along the way —look this rail-line is not crowded right now and railroad officials point out to me that environmental efforts aren't the only things that are important. What they want is a safe reliable to take people in the rural area —from Point A to Point B."

Millions of people each year now ride this rail line — it has become an economic linchpin. Those who work, and ride —know efforts, such as planting trees, and fences that keep sand drifts from blocking the tracks protect the environment and the people.

LI CHENGJUN, Qinghai-Xizang Railway "Protecting the water, and the green mountains, while developing the railroad is now deeply rooted in everyone's heart here. You see it in all their actions, it is deeply entrenched."

He Zhijun is now the unofficial care-taker of the rail line's history. He proudly shows tickets, vouchers, receipts, and other items he's collected while working here 42 years.

HE ZHIJUN, Maintenance Worker, Qinghai-Xizang Railway "This is a certificate of a receipt on the railroad from the 1950s."

This will all end up in a museum — Just like these items, he likes to share his lifetime of memories. It used to take 30 hours to travel from Xining to Golmud. Now the energy efficient train makes the trip in five hours.

The tracks construction is legendary. Working at dangerously high altitude — battling disease, sand, wind, and caustic salt from the Qaidam Basin, and the Qinghai Lake. But people here are equally proud all this has been done, while preserving and continuing to protect this unique - delicate environment. Sean Callebs, CGTN, aboard the Qinghai-Xizang Railroad.