For the first time he took his eyes from the culvert itself and looked around.

The road here descended much more steeply than the railway, and that, Fred judged, was the reason for the culvert.

For the first time he realized that the culvert was not quite at the bottom of the hill; that beyond it the road still bore downward quite sharply for a space, until it turned.

It was plain to him that there were more dangers ahead than those represented by the soldiers on the culvert.
The pace of the rushing car was faster now than would have been altogether comfortable had they been on a road they knew perfectly.
Here, with a curve just ahead that was an unknown quantity, there was real danger in the sheer speed of the machine.

Heavy as the car was, it lurched and swayed from side to side.