Many experts consider 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 right of way, curves, school zones, expressway exit ramps and so forth.
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 clue 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, for example, already display speed limits. 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.
A recent University of Minnesota’s HumanFIRST Laboratory study may have put the idea to rest.
Researchers for the study decided the best method for determining if IVS could replace roadside signage was a real-world experiment. 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 with IVS only and with IVS and external signs.
The likelihood of accidents increases when vehicles sharing a section of road travel at different speeds. Drivers were more prone to drive at different speeds when 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.
When using IVS and roadside signage together, drivers were less likely to speed, and speeds among the drivers became somewhat more uniform.
Researchers also evaluated how drivers interfaced with IVS. Here, 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.
Based on the study, researchers contend that current IVS systems shouldn’t replace roadside signs, despite any projected cost savings. Instead, as with most driver-assistance technologies, IVS should be used in conjunction with roadside signage, because in this limited study, the two working together appeared to reduce speeding and potential crashes.
What it means to you: IVS simply isn’t ready for prime time. In the eagerness to arrive at fully self-driving cars, there’s a tendency to put too much confidence in many of today’s autonomous systems and features. As long as humans are still behind the wheel, IVS should only be thought of as a reinforcement for roadside signage.