By Nick Mackie
The remains of Xiaoyudong Bridge over the Baishui river
The first 17km (10 miles) from Pengzhou offers little clue of the carnage that lies ahead - that is, unless you consider who is going where.
Motoring north along the broad, paved road that follows the Baishui river, there is a stream of military and police SUVs, ambulances and trucks laden with provisions.
Travelling south, to the main city, there are exhausted rescue teams - and evacuees piled into and onto vehicles large and small, some with their livestock.
Soon, the first evidence of the huge landslides that lie ahead appears - on the far side of river, out of harm's way, the sun-baked earth of highway-wide chutes forms 500m-long stripes down the forested mountain sides.
Moving along, Xinxing town is the first along the valley to suffer serious damage.
Most of the roadside homes are reduced to rubble-strewn yards with backdrops of part-demolished dwellings.
Survivors live in the now ubiquitous aluminium-framed, blue canvas tents - either by their old homes or in camps shared with the green tents of the military.
Many families have set about laundering their salvaged clothes and bedding - all hanging out to dry on lines fixed to walls that remain standing.
The military are working flat out, distributing water from mobile tanks, supervising food and bottled water distribution, as well as fumigating paths and makeshift dwellings to ward off disease.
White-smocked civilian health officials are also out spraying.
Xiaoyudong Bridge, 35km from Pengzhou, is down.
The route to Yinchangguo now takes a detour along a dusty trail and over a river crossing made from large concrete pipes, heavy wooden sleepers and rocks.
It is hot.
The local bus ahead is so overloaded with people and possessions that it cannot make it up the steep track and onto the paved road.
The revving creates huge clouds of choking dust.
People salvage what they can from the wreckage of their homes
It is time to don the face mask, rather than wind up the window and rely on petrol-guzzling air-conditioning.
Fuel is in short supply away from the cities.
As we pass a devastated cement factory 5km later, the military checkpoint at Longmenshan town blocks the way.
The road ahead, once a much-loved tourist trail through a stunning gorge, has either fallen away in places or disappeared under landslides.
The army controls this region now - at the forefront of a rescue effort to find survivors and ward off plague.
After negotiating a permit, which was scribbled on a note book, we continue our journey - through the barrier and up a narrow steep track of dried earth and rock formed on a landslide.
We climb - along the winding broken roads, around fallen trees and crushed cars, past one smashed rustic hostel after another.
It is like a war zone.
Along the way, squads of soldiers with long-handled shovels march by - onto their next assignment or back to their camps for a well-earned rest.
Survivors load their possessions onto lorries before leaving the area
They are involved in clearing the roads, looking for bodies, helping returning locals to salvage their possessions - and the all important disinfecting.
Of an estimated 10,000 people in the Jiufeng and Yinchangguo area, few live there any more.
Those by the roadside are loading up trucks and trailers with anything left of value and heading back towards Pengzhou.
The Xie family, however, came back for a different reason.
Speaking to the BBC as they buried their grandmother, the sons explained how a massive landslide followed the earthquake, bringing down a 200m-high mountainside on top of their community.
Somehow, the old lady's body was thrown upwards, so they were able to put her to one side before fleeing.
Scent of death
This landslide engulfed 17 family homes - killing 16 locals and an unknown number of tourists.
There is no sign of any dwelling now.
The landscape has changed.
It just looks like any other broad stony hillside, stretching around 200m along the roadside, extending up hundreds more.
But, here, the scent of death is in the air.
An estimated 800 buildings - from guest houses to home stays - are destroyed along the route from Longmenshan.
Landslides have made the roads almost impassable
At publication of this account, there is no confirmation of the death toll.
The route is now even more dangerous - near-vertical earth walls tower over the roads, huge rocks come thudding down out of the blue, tall uprooted trees rest precariously on the embankment some 5m above passing cars.
Then it becomes impassable - and the military bar entry on foot.
Troops there are working around the clock to clear another mountainside that sheered off in the quake.
And at the far end of this beauty spot, a whole village now lies under boulders and mud.