AASHTO Journal, 15 July 2016
The American Association of State Highway and Transportation Officials has told the Federal Communications Commission that any efforts to share dedicated smart transportation radio spectrum with cable companies or wireless device users must undergo rigorous testing in advance to avoid creating new safety threats to transportation networks.
In extensive comments in response to an FCC solicitation to update the record, AASHTO said devices that may be considered to share the 5 GHz spectrum band with intelligent transportation systems must be fully tested and “be proven harmless before taking any action” to revise longstanding spectrum-use rules.
At issue is whether unlicensed WiFi devices could safely share the Dedicated Short Range Communications band that is increasingly used by emerging vehicle-to-vehicle and vehicle-to-infrastructure systems.
In the comments prepared by two association panels of industry experts – AASHTO’s Special Committee on Wireless Communications Technology and the Subcommittee on Transportation Systems Management and Operations – the association made clear that protecting the 5 GHz band from potential interference can have major economic and safety implications.
AASHTO Executive Director Bud Wright also highlighted the formal comments in a separate message to the association’s board. The FCC, he wrote, “has been under pressure to open up radio frequency channels for WiFi access that could negatively affect the viability of those channels for highway safety purposes. These channels are currently reserved for highway safety uses only – specifically DSRC for connected vehicle use.”
While some content in the formal comments reiterated previous warnings that AASHTO and other transportation groups have sounded, it also updated the association’s message and included a detailed list of major smart transportation projects under way across the nation.
AASHTO said that “a proposed spectrum sharing approach that dedicates only a small portion of the spectrum” to ITS uses “would be unable to account for the nomadic nature of mobile units and would compromise the majority of the DSRC units that would be placed in service.”
It also said efforts to spread smart transportation systems should not be delayed by the push to share spectrum, because the “economic benefits are attractive and massive, and in emergencies are critical to life.”
AASHTO said in emergencies such as Florida evacuations during hurricane warnings, major interstate highways become heavily congested, so smart communications could play a critical role in improving mobility options for drivers to escape the danger zone.
It highlighted the risks of traffic crashes at intersections, and emphasized that any WiFi devices considered for spectrum sharing would need to be carefully tested for the complex communications systems involving traffic lights, connected vehicles, emergency traffic and even buildings in the area.
In addition, AASHTO said any move to share DSRC spectrum with non-transportation systems or to change internationally accepted signaling rates for V2V or V2I communications would require careful negotiations with other nations or else “vehicles used here would become unable to utilize this life-saving technology when crossing our borders.”