[narrator] This is El Chepe... ...an iconic railway line that took a century to complete.

Carved from the inhospitable terrain of Mexico's Sierra Madre.

Beginning in the historic town of Creel, it moves southwest, through the magnificent Copper Canyon region, climbing high mountains, crossing breath-taking bridges and descending steep valleys, before it ends its awe-inspiring journey in the coastal city of Los Mochis.

Filmed from above, this series showcases some of the most incredible railways on Earth.

With spectacular aerial footage, we'll gain a unique insight into these remarkable trains and the extraordinary landscapes they pass through, revealing the technology that built them... ...and the people who keep them running.

We'll uncover the culture, the history and the engineering that makes these truly Epic Train Journeys From Above.

[soft music] Mexico, the third-largest country in Latin America.

Sharing a border to the north with the United States, it's bound to the west and south by the Pacific Ocean, and to the east by the Gulf of Mexico and the Caribbean Sea.

Located in North West Mexico is its largest state, Chihuahua.

And it is here that Mexico's only long-distance passenger train can be found.

El Chepe Express.

Begun as a visionary project to link Mexico's Pacific coast with the plains of the American Northwest, this train travels through a region dominated by the 1,100-kilometer Sierra Madre, and one of the great natural wonders of the world, the Copper Canyon.

[soft instrumental music] Sitting at an altitude of 2,300 meters, the town of Creel is the gateway to the Copper Canyon... ...and it is the main starting point for El Chepe.

The train departs Creel three times a week, and has seating for up to 580 passengers across 16 carriages.

Train manager Mauricio Navarro oversees the entire onboard service team.

[Mauricio] We're gonna check your tickets, your ID, and we're gonna assign the seats, so they can get aboard in different classes.

With nine years' experience on El Chepe, Mauricio enjoys the variety of his role.

For me, it's the best job that I have had in all my life.

I enjoy it because I deal with people, especially to be like the ambassador of Mexico in the Chepe, only train in Mexico, so I love my job, I enjoy it.

We have all the passengers aboard, so are ready to go.

We are ready to go.

Vámonos.

With the final signal from traffic control... ...the El Chepe locomotive and its passenger carriages set off... [train horn blasts] ...departing Creel and heading southwest on a 650-kilometer journey towards the Pacific coast.

From above, the beauty of the journey is plain to see, but the dramatic landscape makes for a challenging route.

From Creel, El Chepe Express climbs as it heads southwest through the Copper Canyon region... ...before beginning a gradual descent towards the mountain lookout of Divisadero.

It then follows a winding path along the course of the Fuerte River to the agricultural heartland of Sinaloa, before arriving in the coastal city of Los Mochis.

As one of Mexico's biggest tourist attractions, El Chepe draws visitors from around the world.

And the crew work hard to make the experience on board as memorable as the scenery outside.

Every journey, all the crew is very satisfied to give the service to the passengers and see the faces when they get off and say thank you.

Whilst maitre d' Carlos Juarez ensures the dining car is ready to welcome guests... ...in the kitchen, chefs Jesús and Jesús are preparing the first of more than 90 meals that will be served across the nine-hour journey.

[soft music] The first stage of the journey takes El Chepe through the high pine forests of the Sierra Madre, a region steeped in history.

South of Creel stands the Church of San Ignacio de Arareko.

It was built by Jesuit missionaries in the 18th century.

The Copper Canyon is also home to the Tarahumara people.

This indigenous group once lived throughout Chihuahua, but fled here after the Spanish conquest.

As well as the onboard crew, there's a whole team of engineers and mechanics keeping the train and the track in peak condition.

Saúl is so passionate about trains, he actually lives in a converted train carriage.

It's not just his home, it's his work, too.

Saúl is one of the maintenance team, responsible for ensuring that everything on, under and inside the train is in perfect working order.

The team has been renovating one of El Chepe's carriages.

Today, they're attaching a new generator to the underside.

[mechanical beeping] For operations manager Ricardo, steady power is particularly important on this route.

With the generator installed, Saúl moves on to the next job.

As well as the generator, there's another vital task for the team today.

Further down the train, the silicone seal around one of the windows has deteriorated, allowing humid air to circulate inside the passenger carriages and condensation to form.

The whole window unit is being replaced.

With each new carriage window weighing 58 kilograms, it takes teamwork to get it in place.

[tranquil music] While Saúl and his crew get the carriages ready, another team is busy stretching and warming up for a day of hard work out on the tracks.

The terrain on El Chepe's route is filled with hazards, from potential landslides and rockfalls to flash floods.

And it's up to this team to keep the tracks open, driving a fleet of specially adapted protector trucks that run 25 minutes ahead of the trains.

Today's crew is track inspector Jose Soto and track operator Omar Bensor.

The pair have been working on the line for seven years, and have developed a sixth sense for problems with the track.

With the train running less than half an hour behind them, Jose and Omar have just enough time for a quick repair.

The tracks are screwed together using pieces of steel known as fishplates.

A gap between each length of rail allows them to expand in the hot summers of the Sierra Madre... ...while the screws and fishplates hold them in position when the temperature drops at night.

Jose and Omar complete the repair in just a few minutes, leaving plenty of time for the train to pass.

But as El Chepe continues to climb towards the highest point on its route, another team of engineers is facing a much bigger problem.

El Chepe Express is now 20 kilometers into its journey southwest through the Sierra Madre.

Although construction on the line began in 1897, it was more than 60 years before the whole route was completed.

As well as contending with a lack of funding and delays due to the outbreak of the Mexican Revolution, the dramatic scenery which draws today's visitors onto the train created huge challenges for the engineers building the line.

Most railway tracks require gentle turns and shallow inclines of less than 5%, and traversing the steep cliffs and ravines of the Copper Canyon took some truly creative engineering solutions.

One of the most pioneering is at El Lazo.

El Lazo means "The Loop," and here the track curves eight degrees to make a wide 360-degree turn, allowing it to spiral down a steep mountainside and quickly lose altitude.

It can test both engine and track to their limits, and today the crew aboard the protector truck has spotted a problem.

With warning flags in place to alert oncoming rail traffic to their presence, they need to repair a damaged piece of rail.

The curved tracks of El Lazo mean that passing trains have exerted extra pressure on the rails, leaving a crack that will only worsen if left unrepaired.

[mechanical whirring] And the team has no time to lose.

With the damaged piece of track now cut out completely, a mold is attached and the rail is heated.

Meanwhile, a special solution of iron and aluminum oxide is mixed in a ceramic crucible.

Once ignited, this material will create an exothermic reaction.

The heat created by this reaction is so intense that the iron in the crucible melts, flowing down into the mold and filling the gap in the railway tracks.

With the mold removed, there is still excess metal around the join, enough to derail a passing train.

[hammering] The team now use sledgehammers and an angle grinder to remove the red-hot metal and smooth out the weld to create a perfect join.

[mechanical whirring] This technique, known as thermite welding, was first used to join stretches of railway line in 1899.

It can be used in locations without access to electricity, making it invaluable in the remote regions of El Chepe's route.

In just moments, the newly repaired section of the track will be put to the test.

[train horn blasts] The weld is a success, and the track is held firmly in place.

From above, we can see how El Chepe passes safely through this marvel of railway engineering... ...using a series of gentle curves to cross over itself as it descends deeper into the Sierra Madre.

With 58 kilometers of the route completed, El Chepe Express is now approaching the first major stop on its route, the mountain settlement of Divisadero.

It's one of the highlights for visitors, who come to experience the incredible views.

And sidings have been built for passengers to disembark at the station.

Switching the tracks is done the old-fashioned way.

[Mauricio] We're about to arrive to Divisadero.

We're gonna leave the main track.

The guys in the front of the engine, they're gonna make the change of tracks for people to get in, and we're gonna stay there for around ten, 15 minutes.

It depends on the people to get aboard.

Manually aligning the tracks is the job of signalmen Obed Davasco and Marco Antonio.

[indistinct radio transmission] With the track switched, the signal can be given for the train to proceed.

Standing at an elevation of over 2,200 meters, Divisadero means "lookout" or "viewpoint," and is the highest stop on the route.

Here, the train's passengers can disembark to sample the local indigenous culture, experience the thrills of the highwire adventure, or simply stand in awe of one of the world's great natural wonders... ...the Copper Canyon.

Carved out over the millennia by the six major rivers that flow through it, it is four times larger than America's Grand Canyon and is listed as a UNESCO World Heritage Site.

Building a railway through this terrain meant not just climbing and descending mountains, but tunnelling through cliffs and bridging deep ravines.

Keeping this unique stretch of line running safely remains a constant challenge for today's maintenance crews.

[dramatic music] El Chepe Express is still at high altitude, passing through the mountainous terrain of Mexico's Sierra Madre.

From just outside Divisadero, it begins the first stages of a winding 150-kilometer descent that will take it southwest, towards the coastal state of Sinaloa.

In the 1950s, after decades of delay and political upheaval, the final section of El Chepe had still not been built... ...so the Mexican government began a final push to complete the railway through the Copper Canyon.

In the decade that followed, 6,000 men blasted 82 tunnels, put up 37 bridges, and laid 250 kilometers of track through some truly extraordinary terrain.

Mexican engineers welded steel lengths of track, while Tarahumara tribesmen cut wooden sleepers from the forest.

And by 1961, the first passenger train was finally able to pass all the way from Chihuahua to Los Mochis.

The work of El Chepe's creators still stands.

But it is vulnerable to dangers of erosion and rockfalls, and requires regular maintenance.

Halfway through their shift, protector truck crew Jose and Omar are carrying out an inspection of one of the route's many tunnels.

Fifteen inches of rain can fall in a few short months in the Sierra Madre, flooding tunnels and eroding their walls.

They also check the whole length of track inside the tunnel.

[metallic clanking] With the tightening completed between two sections of rail, the crew can move on.

[exhilarating music] The route's 37 largest bridges also need regular maintenance, and getting underneath a bridge to look for structural issues requires some highly specialized equipment.

Sixteen kilometers from Divisadero stands the elegant La Laja Bridge.

At 155 meters in length, it crosses the La Laja Canyon, a 50-meter ravine, carved out by a tributary of the Septentrion River.

The bridge was completed in 1960 as part of the final construction phase of the El Chepe Line, with cement for its four concrete pillars mixed using aggregate from the bed of the river below.

Today, keeping it safe is the work of bridge engineer Marco Ortiz and his team.

Bridges are checked twice a month along the El Chepe route as a matter of course, and more regularly if any concerns are recorded.

Today, the crew is using an Aspen A-30 bridge inspection truck known as "The Nest."

With a potentially fatal drop into the canyon on either side, the safety of the team is of paramount importance.

With the crew secure and the checks complete, the bridge inspection unit moves out over the canyon.

Once it's in position, Marco gives the go-ahead.

Weighing more than 20 tons, the Aspen A-30 uses a hydraulic crane arm with an aluminum platform to lower the inspection engineer as much as 12 meters below the level of the tracks.

[mechanical whirring] Today, he is checking each of La Laja's four pre-stressed concrete pillars for signs of damage from extreme heat and cold.

The Nest has a maximum lift rating of 272 kilos, and with low winds and safety harnesses tightly secured, the engineer can feel relatively safe.

But with a 50-meter drop below, carrying out the inspection takes a cool head.

With the work complete, it's a relief to get back to the rest of the team.

With the all-clear given, it's time for normal traffic to resume on the La Laja Bridge.

This engineering masterpiece united the skills of some of the world's greatest engineers with the manpower of the local Tarahumara.

Today, these indigenous communities and their cultures draw visitors from around the world, and have a vital part to play in keeping El Chepe alive.

[lively music] El Chepe Express has now descended nearly 1,000 meters from its high point in the Sierra Madre, and is approaching the settlement of Bahuichivo.

The rise of air and road transport means that today, El Chepe is one of Mexico's only remaining passenger trains, and caters primarily to the tourists who come to visit Copper Canyon.

In the dining car, maitre d' Carlos Juarez is keeping his passengers refreshed under challenging conditions.

As you can see, it is, uh, really rocky at the moment, the train is moving a lot.

So that is quite a challenge for us to serve the drinks, to serve the food, but... We are getting used to it, or we are used to it already.

The Chepe Line was built to provide a link between diverse regions and cultures.

And in the train's kitchen, father-and-son team Jesús and Jesús are preparing a menu rich in local product.

We try every time to have local products, Mexican products mainly, but mostly from Chihuahua and from Sinaloa.

[tranquil music] Seen from above, the arid wilderness of the Chepe route may not look like a promising place to source the ingredients for a chef's pantry.

But the unique geography of these mountains holds some surprising secrets.

And for winery owner Bernardo Balderrama, it's the perfect environment for producing one of El Chepe's most famous luxuries.

Right now, we're in the main vineyard of Misión de Cerocahui.

So this is the Valley of Cerocahui.

It's in the middle of a basin, and it has a very special microclimate.

This microclimate is very different in that in all Mexico, it's compared to Burgundy in France.

That's why you see pine trees and you see different vegetation.

And this weather, you know, it's cool nights, you know, and hot days, makes it excellent for the grapes.

Bernardo has been supplying the Chepe train for the last five years, but the vineyard has its roots much further back in the region's history.

This vineyard dates to the 1780s, when the Jesuits, they came here into this land.

They were coming here to, er, propagate the Catholic religion, but also they brought with them the vines to grow them and to make their own wines, especially for the ceremony in the mass.

Aboard El Chepe, the fruits of Bernardo's vineyard provide a welcome addition to the menu.

It is important to have a good quality of wine, because we are, of course, serving a good quality of food.

So, if we have good drinks, good wines, good food, we are giving a great experience to the customer.

We are giving a great experience to passengers.

Like the grapevines at Cerocahui, apples also arrived with the Spanish in the 16th century, where they flourished in the cool heights of the Sierra Madre.

Today, Chihuahua produces more than 70% of Mexico's annual apple harvest, 3% of the country's commercial fruit production, and they also find their way into the Chepe kitchen.

But there's another specialty served on the Chepe train that is truly local.

Unlike wine, sotol can only be made using a wild shrub from which it takes its name.

The slow-growing sotol plant is closely related to asparagus, and is found only above 900 meters in the heights of the Sierra Madre.

To keep the train supplied, distillery owner Victor Ibarra needs a sturdy four-wheel drive and a sound knowledge of the desert.

[Victor] As you can see, we're, like, probably 1,600 meters, altitude-wise, and, uh, this is very favorable for the plant to, to really grow, and, uh, and develop.

As you can see, it's more...

It's like, very caliso, we call it.

It's a type of terroir that we have over here.

So, it's dry, but during the winter it can get humid, you know, and it's when the plant will get its sugars ready after raining season.

[light instrumental music] In the early 20th century, the Mexican government banned sotol.

Some makers kept production going illegally, smuggling the drink into the United States during the Prohibition era.

In recent decades, production has been revived.

The traditional methods of the sotoleros use underground ovens and fermentation to bring out the natural sweet flavors of the sotol plant.

For Victor, the transformation of this hardy desert shrub into a fragrant liqueur never loses its magic.

When we get to the middle part, we can take some pieces of it and really taste the sweetness of it, which is a very interesting, and different kind of sweetness.

To test the final product, he turns to his master sotolero, Gerardo Ruelas.

[Victor] Gerardo is fifth generation.

He represents the fifth generation of sotoleros.

For generations of Gerardo's family, practicing this craft meant risking jail.

Today, his expertise is back in demand.

With the latest batch bottled and signed off, there's just enough time to get it to the Chepe train.

So, we have a delivery to make to El Chepe.

Just happened.

[engine revving] Thanks to El Chepe, sotoleros like Victor and vineyard owners like Bernardo can bring the heritage and culture of the Sierra Madre region to people from all over the world.

But as the train continues its journey through this mountainous region and encounters the people who have made this landscape their home, this railway's most surprising secrets are yet to come.

[light instrumental music] Today, the Chepe Railroad is popular with tourists from around the world, drawing nearly 100,000 people each year.

They come here not just for its unique landscape, but also for its culture.

I was excited to see the people, the Tarahumara people.

[woman] I like about it's not only trees.

You can see, well, a history of the Tarahumaras, and everything has happened over here, how both cultures are coexisting here.

[tranquil music] From above, the remote terrain of the Copper Canyon may appear inhospitable, but for many, this landscape has been a place of refuge.

The Mennonites, a religious Christian group, settled in Chihuahua in the early 20th century, and the region has also provided a refuge for the indigenous Tarahumara people.

Persecuted by the Spanish in the 16th century, they fled to the remote regions of the Copper Canyon and still live here to this day.

Tourists from the Chepe train bring valuable income to remote Tarahumara communities.

[buzz of conversation] But for Guadalupe Aguero, their culture offers something else.

When I came here to these mountains for my first time, I got in love what these people, they can do.

So, I started training and training and training, until I got to complete my first...

The first time 60... 60 kilometers.

So, I felt in love, what you receive from the people.

Guadalupe is an ultra marathon runner, competing in long-distance races that can range from 50 to 100 kilometers in length.

And thanks to El Chepe, today he's come to meet a special training companion.

The reason that I come to visit Martin Moreno, because I know that he can run 100 kilometers or more.

I'm excited to run again with Martin, because I know his power and I know my power.

That is, I don't compare with him, but I do my effort to go more than he can.

So, that's my reason to come.

The Tarahumara have a reputation as extraordinary long-distance runners.

Long before the Chepe Railroad connected these mountains to the coast, Tarahumara like Martin Moreno used long-distance running as a practical way to travel from village to village, covering as much as 80 to 100 kilometers a day, using only leather sandals and stamina.

Today, this deeply rooted part of their culture has seen Tarahumara athletes triumph in international competitions.

For Guadalupe, a seasoned Tarahumara runner is the ultimate mentor.

[Guadalupe] That's why I'm training with Martin, because I know that following him, it's gonna be hard so...

If he goes to the Ultramaratón de los Canones I will follow him all the time.

Well, it's good in this area, so the terrain gets your ankle really, really strong.

So, let's do it!

Their ability as outstanding long-distance runners has made the Tarahumara famous around the world.

And their agility on the rocky mountain ridges of Copper Canyon is reflected in the meaning of their name, Tarahumara, meaning "the light-footed people."

Other runners, they look for Tarahumaras, so that's one of the reasons I looked for Martin because I knew that I'm gonna improve myself, that I'm gonna be training with him, so I'm gonna have my legs or my body, my mind even, because when you run ultra marathons, hasn't your legs, your power, it's more in your mind.

[train horn blasts] [rousing music] The Chepe route has been a vital link between remote Tarahumara communities and the rest of the country since it first opened.

The final stretches of track were laid just outside Témoris.

Here, the train must make a steep 200-meter descent to the valley floor below.

To do this, it first enters the 930-meter Le Pera Tunnel.

The train then doubles back on itself, turning a complete 180-degree loop inside the mountain.

Emerging from the tunnel, the train then descends along the valley walls before the track loops again, crossing the 200-meter curve of the Santa Barbara Bridge and returning to its original course at a lower altitude.

This triumph of engineering was completed in 1961, finally linking the inland city of Chihuahua with the Pacific coast.

And today, a plaque stands at the Temoris Loop to commemorate this historic achievement.

As the train continues down towards the coastal state of Sinaloa, it faces a new and growing environmental threat.

[soft instrumental music] The Chepe Route might be a marvel of railway engineering, but a changing world means it constantly faces new challenges.

As the train heads towards the plains of Sinaloa, it becomes vulnerable to a recent increase in extreme weather.

In 2018, floods caused by record-breaking rainfall forced the Chepe Line to close for several weeks.

Three years later, it happened again.

[pensive music] With baking sun and torrential downpours damaging the tracks, division engineer Manuel Perez and his team are doing what they can to safeguard for the future.

Lightweight, cheap and easy to manufacture, wooden sleepers have been standard since the early days of the railway, and can last for 50 years.

But extreme weather has damaged them.

Even a slight change in the distance between tracks could spell disaster for a passing train.

Manuel and his team need to solve the problem.

[indistinct conversations] They might be made from a more durable material, but installing the new sleepers by hand isn't easy.

With 4,000 wooden sleepers in need of replacement, the crew's work looks set to continue.

As it finally leaves the foothills of the Sierra Madre behind, the Chepe train finds itself on the coastal plains of Sinaloa.

[cattle bellowing] This fertile state is Mexico's agricultural heartland, producing wheat, sugarcane and other commercial crops.

From here, it's a short run to the Pacific coast and the train's final destination, the city of Los Mochis.

[dramatic music] Founded in 1893, Los Mochis built its fortune on the sugar industry, and the remains of the old sugar refinery still stand to this day.

As the train approaches the end of its journey, it's time for the passengers to reflect on a memorable trip.

It's my first time and I...

I am really enjoying the... the trip.

I think it's been a good experience.

And for the crew, it's a chance to wind down after a long shift.

[Carlos] It's been a busy day today.

We are almost finishing our shift.

We're heading to Los Mochis, and we served around 800 people during this trip.

Everybody was happy, everybody enjoyed the trip, so it was fine.

It was very fun today.

It was a great day.

After a distance of 650 kilometers and a breath-taking descent of over 2,000 meters, El Chepe Express comes to its final stop.

[exhilarating music] From the heights of the Sierra Madre, past cliffs and winding rivers of the Copper Canyon and on to the coastal plains below, El Chepe Express has mastered a landscape like no other.

It's a journey of diverse and interconnected worlds, rich in local culture and centuries of Mexican history, all joined together by an iconic trainline.

And as it descends from cool mountain heights to tropical valleys, it is the train's staff and the engineering crews of this railway who keep it thriving in an ever-changing world... ...making El Chepe one of the truly Epic Train Journeys From Above.

[exhilarating music playing out]