Many car experts consider that one of the benefits for local and state governments from the technology for totally self-driving cars would be the elimination of traffic signs along the road informing drivers of speed limits, the rights of way, curves, school zones, expressway, and exit ramps.

That seems like a fairly logical assumption. After all, why would cars capable of navigating themselves from place to place and through traffic need instructional road signs? We have no estimate of how much money highway departments might save by not erecting and maintaining such signage, but it'd probably amount to a considerable sum.

In the meantime, many new cars, brimming with driver-assistance technologies, are already capable of posting some of the same information provided by roadside signage on the vehicle's touchscreen or head-up display. Many of today's in-car navigation systems already display the speed limit. Such in-vehicle-sign (IVS) systems, even in human-controlled cars, could accelerate the elimination of at least a few roadside signs, some experts speculate.


Researchers for the study have decided that the best method for determining if IVS could replace roadside signage would be a real-world experiment or not. Mapping a 24-mile route in southern Minnesota that included city streets, rural roads and expressways, they created a test route featuring an array of roadside instructional signs. Test subjects then drove the route using IVS only.

Key findings:

The probability of accidents increases when vehicles sharing a section of road and travel at different speeds. Drivers were more susceptible to drive at different speeds when they are relying only on IVS for their instructional information, and drivers were also more likely to exceed the speed limit when using IVS only. Researchers concluded that IVS-only driving reduced safety across all types of crashes.

Researchers also assessed how drivers interfaced with IVS. They found that IVS alone increased a driver's mental workload more than using roadside signs alone or using IVS and roadside signs in tandem. Driver satisfaction with IVS was higher when supplementing roadside signs than when used alone.

Keywords: Self-Driving Cars