A travelers' information station (TIS), also called highway advisory radio (HAR) by the United States Department of Transportation, is a licensed low-powered non-commercial radio station, used to broadcast information to the general public, including for motorists regarding travel, destinations of interest, and situations of imminent danger and emergencies. They are commonly operated by transportation departments, national and local parks departments and historic sites, airport authorities, local governments, federal agencies, colleges and universities, hospitals and health agencies, and special events and destinations.
United States
Current regulations and applications In the United States, most Travelers Information Stations (TIS) are licensed by the Federal Communications Commission (FCC), although stations operated by U.S. national parks and others under U.S. federal government jurisdiction are licensed by the National Telecommunications and Information Administration (NTIA). Programming normally consists of continuously repeated pre-recorded messages. Permissible station content is defined by the FCC as:
... only noncommercial voice information pertaining to traffic and road conditions, traffic hazard and travel advisories, directions, availability of lodging, rest stops and service stations, and descriptions of local points of interest. It is not permissible to identify the commercial name of any business whose service may be available within or outside the coverage area of a Travelers' Information Station. However, to facilitate announcements concerning departures/arrivals and parking areas at air, train, and bus terminals, the trade name identification of carriers is permitted. Travelers' Information Stations may also transmit information in accordance with the [safety and emergency communication] provisions of §§90.405 and 90.407. Most TIS/HAR licenses in the U.S are held by governmental entities, in addition to quasi-governmental agencies and authorities as well as health and emergency service providers working in conjunction with the government. Stations may be licensed to operate on any AM band frequency from 530–1700 kHz. (In a single case—WQFG689, licensed to the County of Hudson, New Jersey—a station has been authorized to transmit on 1710 kHz. 1710 kHz is also in use by a number of federally licensed stations.)
A majority of TIS stations operate on 530 kHz, which is reserved exclusively for use by this service, and on the AM expanded band frequencies of 1610–1700 kHz, which is the least congested portion of the AM broadcast band. On 1610 kHz, TIS service stations have a co-priority status with broadcasting stations, while on the remaining standard AM broadcasting frequencies, 540 kHz-1600 kHz and 1620–1700 kHz, TIS stations are considered a secondary service, with priority held by standard broadcasting station assignments. Although initially envisioned as providing general information to motorists and travelers, TIS stations have also been developed for supporting emergency public safety communication, and the FCC currently licenses the stations through its Public Safety and Homeland Security Bureau (PSHSB). During a crisis, mobile phone networks are often overloaded, and TIS stations can be used to broadcast emergency instructions. Also, during a widespread electrical outage stations equipped with reserve battery or generator power can continue operating, for reception by battery-operated radios. In 2008, the American Association of Information Radio Operators (AAIRO) was formed to represent station operators, and at the time of its formation the group emphasized the ability of TIS stations to broadcast live local updates to affected communities during emergencies. Two forms of transmitting antennas are employed. Most commonly used are standard non-directional vertical antennas. However, an alternate implementation, called "leaky cable", is a form of carrier current transmission, which employs long horizontal conductors, commonly run alongside roadways. Stations using a standard antenna are generally limited to a coverage radius of 1.9 km (1.2 mi), with an antenna height of no more than 15 m (49 ft), and a maximum power of 10 watts, although special events and critical evacuation systems, such as those in the Florida Keys and near chemical and nuclear facilities, have been granted waivers to exceed that limit, typically for up to 100 watts. Individual "leaky cable" installations are limited to a length of 1.9 km (1.2 mi), although "ribbon systems" consisting of installations sequentially located along a travel route are permitted. Because cable installations are less effective radiators, they are permitted to use up to 50 watts order to achieve a maximum of 2 mV/m at 60 m (200 ft) from the cable. In order to limit potential interference to stations operating on adjacent frequencies, TIS transmitters are required to employ a low-pass filter to reduce the transmission of audio frequencies higher than 5 kHz.
TIS service history The TIS service was first authorized by the FCC in 1977 following two years of study. At this time, the standard AM broadcast band ran from 540 kHz to 1600 kHz, and the new TIS service was initially assigned exclusive use of the two adjoining frequencies of 530 kHz and 1610 kHz. However, on June 8, 1988, an International Telecommunication Union conference held at Rio de Janeiro, Brazil, adopted provisions, effective July 1, 1990, to extend the upper end of the AM broadcast band in the Americas, by adding 10 frequencies which spanned from 1610 kHz to 1700 kHz.
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