When I picked up the Forester, my intention was simply to replace my last vehicle, an Outback. But a test drive changed my mind, largely because of how much more of the road I could see in the Forester. I was more able to see past the vehicle immediately in front of me. But therein comes a trade-off.
Height might offer a higher perception of safety, but it comes with its own risks. Simulator studies have shown that drivers seated at higher eye heights drove faster on average than drivers of vehicles closer to the ground—often without being aware of it.
As I wrote in my book Traffic, the “textural density” of what passes us as we drive influences our sense of speed. Things like roadside trees or walls affect the texture, as well, which is why drivers overestimate their speed on tree-lined roads and why traffic tends to slow between noise-barrier “tunnels” on the highway. The finer the texture, the faster your speed will seem.
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However, the fineness of road texture is itself affected by the height at which it is viewed. We sense more of the road’s optical flow the closer we are to it. When the Boeing 747 was first introduced, pilots taxied too fast, on several occasions even damaging the landing gear. Why? The new cockpit was twice as high as the old one, so pilots were getting half the optical flow at the same speed.
A driver sitting higher up can also see more of the road (what’s called “sight distance”), which can theoretically be safer—but drivers with a higher view tend to think the vehicle in front is farther away than it really is. So that added safety margin may simply be consumed.
Tom Vanderbilt is author of Traffic: Why We Drive the Way We Do (and What It Says About Us).