At first glance, the red straight line in the image seems like the most logical and quickest solution. However, in road engineering there are important technical reasons to avoid straight lines on terrain like this:
1. The slope of the land (Topography)
The main reason is the incline. If you look at the vegetation and the perspective, the road is climbing toward a hill or mountain.
If the red straight line were built, the slope would be too steep.
Ordinary cars would lose traction, heavy trucks simply would not be able to climb, and going downhill would be extremely dangerous due to brake wear and failure. The curve serves to lengthen the distance and make the climb gradual and safe.
2. Road safety and fatigue
Extremely long and monotonous straightaways encourage drivers to speed too much or cause highway hypnosis (drowsiness). Introducing gentle curves and changes in direction keeps the driver alert and helps naturally regulate vehicle speed.
3. Natural obstacles and costs
Although from above it may look green and uniform, the terrain may have hard rock formations, geological faults, or hidden streams in that central area. Going around the terrain by following the mountain’s contour lines is usually much cheaper and more environmentally friendly than blasting rock or building massive bridges and tunnels to maintain a straight line.
