The Waterfall Crossing
I could not believe that we were going to cross the waterfall. We had been traveling up a steep grade for hours working our way up into the high Himalayas, and now at the bend in the road where in dryer seasons there undoubtedly would have been a creek tumbling down the hillside, there was instead a full-on waterfall. The water was cascading from a least 100 feet high above us on the mountain side of the road and falling into a plunge pool near the asphalt. From there it raced across the road in a roaring froth and dropped off the edge of the road on the other side into another waterfall that cascaded down the drop off tumbling at least another 150 feet. From there it hit rocks and cascade in a series of waterfalls at least another thousand feet down the slope below us. Then it tumbled in a bed of nothing but angular boulders another thousand feet. It was the same route that any vehicle swept off the road in the cascade would take – 2000 feet of tumbling and rolling before coming to a stop on gentler slopes down the mountainside. The water racing across the road was at least 3 feet deep, maybe more – definitely deep enough to sweep a bus right off the asphalt.
Our driver had stopped to consult with his mechanic. They both had gotten out of the bus and were standing by the edge of the torrent crossing the road, occasionally shouting to the truck driver on the other side who also had stopped and was looking at the torrent evaluating his chances. There was somewhere around 75 feet of water that had to be crossed, deepest in the middle to about 3 feet. As an engineering geologist I knew that flash floods (fast-moving water and debris) had enough hydraulic pressure to lift a car right off the road once the water reaches the running boards of the car. Would it do that to a bus? It was obvious that the water was higher than the clearance of the bus and it was moving fast enough to exert a huge amount of pressure against the side of the bus once it hit it. That, in combination with the hydraulic pressure lifting the bus up off the road – would it be enough to push the bus right over the edge? A glance over the edge showed the exact route that the bus would take for the next 2000 feet if the resistance on the tires could not maintain pressure on the road when we got to the center of the torrent. I kind of felt sick. I wanted to get out.
I look at the driver standing out by the water and thought “why don’t we just get off the bus before you try driving across…”
But I already knew the answer. If anybody got off the bus there would be no way for them to cross the torrent and rejoin the group should the bus have a successful crossing. In addition, the passengers on the bus added extra weight providing more chance to make it across the torrent. It wasn’t just the bus driver’s gamble I knew; it was mine as well. If I thought the bus wouldn’t make it, I knew I’d better get out now. We had no ropes, we had no chains, and even if we did there was nothing to anchor the bus to while it tried to cross.
Two cars pulled up behind the truck coming down the mountainside. Both of the drivers got out and evaluated the racing torrent going across the road. One of them got right back in to do a three point turn on the road and drove away back up the mountainside. The other one spoke with the truck driver for a few minutes, then he too did a three point turn and drove away. It was plainly obvious no car was getting across this waterfall torrent. The truck driver and the bus driver on opposite sides of the torrent spend more time talking, and then the bus drivers and the mechanic climbed back into the bus. I knew from the way that he got in his seat and closed the door that he was going to try and cross the torrent. Any chance I had to leave the bus was gone. Indecision had made my decision for me. Apparently the truck driver and the bus driver had agreed that the bus should go first. Because the truck was coming down the mountain, it was probably empty returning from delivering its load while the bus was full giving it more weight.
We started inching into the water slowly. I could feel my face drain and I know I was white. I didn’t say a thing – nobody did – the driver; the mechanic; the geologists and the trekkers – the whole bus went silent. I knew they were thinking the same thing that I was. I realize that I was grabbing tight to the seat in front of me and wedging my legs underneath my own seat to hold myself in place. And at the same moment I realize how futile that action really was. Two thousand feet of tumbling futile. In just a few minutes the whole thing was about to be over in one way or another. The bus driver continued to inch forward. I chose a view on the waterfall side so I could see how badly the water was piling up against the side of the bus as we drove through it. I pressed my head against the side of the window trying to see straight down the side of the bus as well as I could. I couldn’t quite see the edge of the bus below my seat next to the window, but I could see the water right next to the bus. The bus driver continued to inch forward and I could tell exactly when we entered water higher than the clearance of the tires. The water began to “pileup” below me and stream off towards the front and the rear of the bus to get around it. We hadn’t yet reached the deepest part. I knew that now it was a contest of physics; would the hydraulic pressure trying to float the bus, combined with the hydraulic pressure pushing the bus sideways, overcome the frictional pressure of the tires on the asphalt exerted by gravity? We continued to inch forward.
I knew that once the bus started to drift sideways the game was over. It wouldn’t re-stabilize, there would be no backing up. The amount of energy required to overcome friction is far greater than the amount of energy to maintain movement of the object once the friction is overcome. If the friction of the tires broke free of the asphalt and we started to drift sideways, that would be it. The tires wouldn’t reconnect with the asphalt, they’d simply slide along until the bus was pushed over the edge.
It’s funny what you think about when you’re in that kind of the situation, I remember noticing that the windows were sealed and couldn’t be opened; there was no way I could jump out of them if we started to drift. I even looked and judged how far it was to the door and how long it would take me to get to it, but the door was on the downstream side of the bus, so if I did manage to get out of it, the bus would just scoop me off over the falls. I couldn’t jump from the windows or from the door, and even if I could the torrent would carry me over the edge too. My mind was racing but I couldn’t find an escape route. The bus driver continued to inch forward.
Next week: The Waterfall Crossing (continued)