Traffic Control Systems Handbook: Chapter 10. Traveler Information Systems

Figure 10-1. Traveler Information Kiosk

10.1 Introduction

From the point of view of the motorist, one of the most important functions of any traffic management system is the dissemination of information. Information dissemination to travelers includes both pre-trip planning information, as well as real-time en-route information. Although information dissemination is often associated with freeways, it has become increasingly important on surface streets as well.

10.2 Static Signs

Static signs convey only one message. Single-message displays are most useful in recurrent situations where the engineer desires the same driver response each time. Therefore, the engineer should position static signs in locations where the message always proves meaningful.

The Manual on Uniform Control Devices (MUTCD) remains the principal source of standards for static signs (2). The MUTCD also provides the traffic engineer with guidance on signs relative to:

• Use,
• Design,
• Application,
• Placement, and
• Maintenance.

The Traffic Engineering Handbook (3) further clarifies some terms and procedures identified in the MUTCD. The Handbook discusses practical implementation and refers to other State and Federal documents that fill in details purposely left open by the MUTCD. Many states have standards that define their implementation of the MUTCD.

Static signs are classified into three basic types:

• Regulatory signs that inform roadway users of:
  • Traffic laws or regulations, and
  • The applicability of legal requirements otherwise not readily apparent.
• Warning signs inform roadway users of potential or existing hazardous conditions on or adjacent to a highway or street.
• Guide signs inform roadway users of:
  • Directions to common destinations,
  • Roadway identification via route markers, and
  • Other valuable information.

State laws allow for enforcement of these signs by police and other local authorities.

Table 10-1 provides examples of the intended use of each basic sign type.

Table 10-1. Static Sign Use

Static Sign Type	Purpose	Typical Uses
Regulatory	To inform motorists of traffic laws and regulations	Intersection control Definition of right-of-way Speed limits Turning movement control Pedestrian control Exclusions and prohibitions Parking control and limits Regulations associated with roadway maintenance and construction Preferential vehicle (e.g., HOV) lane use School zone restrictions Railroad-highway at-grade crossing control
Warning	To warn motorists of unusual existing or potentially hazardous condition (s) on or adjacent to a street or highway	Roadway width and horizontal and vertical alignment changes School areas Crossings and entrances to streets, highways, and freeways Impending intersection controls Road construction and maintenance Roadway alterations Advisory speeds Unexpected crossing areas Railroad-highway at-grade crossings
Guide	To provide destination and directional information	Route markings and mile markers Destinations and directional arrows Distances to destinations General motorist services Tourist, recreational and cultural interests Roadway construction and maintenance detours Exit numbering Emergency evacuation routes

Though normally considered passive, static signs can be transformed into active signs by adding flashing beacon signals. An active sign's message is valid only when the signals flash. An example is:

"School Speed Limit XX MPH When Flashing."

Figure 10-2 depicts an active sign. Note the solar panels that power the flashing beacons. This display type compares favorably to changeable message signs in terms of both cost and the agencies' capability to fabricate it.

Figure 10-2. Active Sign.

Active signs typically see use in traffic management functions and provide a lower cost solution than blank out signs (a form of changeable message sign). Section 10.3 further describes blank out signs. A time-clock switch closure or a communication signal can readily activate the flashing beacons associated with active signs.

Traffic engineers also add extinguishable blank out text to static signs, thus creating a hybrid. The blank out text activates when applicable and supplements the static sign message. Figure 10-3 shows blank out sign text added to a static guide sign.

Figure 10-3. Static Sign Hybrid.

The MUTCD also recommends the use of diagrammatic guide signs along freeways to:

• Graphically depict the exit arrangement in relationship to the main highway. Such guide signs have proven superior to conventional guide signs for some interchange types
• Use at advance guide sign locations where:
  • Splits have off-route movements to the left,
  • Optional lane splits exist, and
  • Exits where route discontinuity and left-exit-lane drops exist .

The MUTCD also includes standards for:

• Sign background,
• Letter color, and
• Shape and size.

Many signs for roadway maintenance and construction areas largely duplicate normal regulatory warning and guide signs. To identify their temporary character, all roadway maintenance and construction signs use an orange background.

The MUTCD also addresses signs for HOV and bicycle facilities, and provides information on the use of guidance devices such as:

• Object markers,
• Pavement markings, and
• Roadway delineators.

Recent developments in static signs include:

• Solar-powered light emitting diodes (LEDs) to further self-illuminate static sign messages, and
• The addition of yellow or red LEDs to diagrammatic guide signs to indicate congested road sections.

Figure 10-4 depicts a static yield sign with LEDs incorporated to further distinguish the sign and draw attention to it.

Figure 10-4. LED Illuminated Static Yield Sign

Figure 10-5 shows another method of internally illuminating static signs. The enclosure contains fluorescent lamps behind the sign panel that improve the sign's visibility.

Figure 10-5. Illuminated Fluorescent Sign

10.3 Advanced Methods of Information Dissemination

Static signs are the most basic method of information dissemination. Advanced technologies provide additional methods of giving information to travelers. These methods may be broadly classified as on-roadway and in-vehicle, or off-roadway. For more detailed information on the technology used in the various methods, refer to the Freeway Management and Operations Handbook 

• On-Roadway and In-Vehicle:
  • Changeable Message Sign (CMS): CMS signs are a variety of different types of signs that display changeable messages to give motorists real-time information on local conditions. CMS may be permanent or portable. Table 10-2 identifies some applications of CMS. Figure 10-6 shows an example of a surface street CMS.
  • Highway Advisory Radio (HAR): HAR uses a special radio station to give information to travelers. A HAR system consists of a radio transmitter to transmit the information, and signs telling motorists what radio station to tune to. The signs usually include beacons that flash when there is an important HAR message. Although primarily used for freeways, HAR may be used in limited ways on surface streets. HAR may be permanent or portable.
  • Cellular Telephone Hotlines: Cellular phones can be used to access special hotlines with route-specific traffic information. In response to the U.S. Department of Transportation's petition the Federal Communication Commission (FCC) designated 511 as the national traveler information telephone number.
  • Commercial Radio: Commercial radio stations often include traffic reports.
  • Citizen-Band Radio: CB radios allow two-way communication between a motorist and a response agency, and are useful in a motorist aid service. Although CB radios are not as popular as they once were, they are still found in a significant number of trucks and commercial vehicles.
  • In-Vehicle Route Guidance Systems: Video Display Terminals (VDTs) may be mounted on the dashboard, and provide real-time route guidance and navigational information to the motorist. They can display information either on a map, which can highlight the recommended route, or by displaying text and simple symbolic signals (such as an arrow). This type of information may also be provided by voice. Surveillance information may be used to take current traffic conditions into account in the development of route guidance paths.

Table 10-2. Applications of CMS on Surface Streets

Category	Applications
Traffic management and diversion	Surface street and freeway traffic advisory and incident conditions. Parking availability Special events Adverse road conditions Speed advisory
Warning of adverse conditions	Adverse weather and environmental conditions (snow, ice, fog, slippery pavement, high water) Evacuations and emergencies
Control during construction and maintenance operations	Advisory of existing or upcoming construction / maintenance Speed advisory Path control
Control of special use of lanes	Reversible lanes Exclusive lanes Contraflow lanes Restricted roadways

Figure 10-6. CMS on surface street.

• Off-Roadway: Access while not in a vehicle can be useful for pre-trip planning.
  • Television: Many commercial television stations provide traffic information, either as a scheduled part of their morning program, or by interrupting regular programming.
  • Telephones: Telephone hotlines may be used to provide pre-trip information, and also for real-time ride sharing matching.
  • Pagers: Alphanumeric pagers are another device that can be used to obtain pre-trip information. Motorists can receive hourly information on traffic and rideshare matching sent to their pagers.
  • Personal Data Assistants (PDAs): PDAs can be used in conjunction with RF communications to receive real-time traffic information, allowing more detailed information than an alphanumeric pager.
  • Computers (Internet): In recent years, the internet has become one of the most important methods for information dissemination. Many areas have public agencies and private services that display real-time, route specific traffic information. The internet can also be used to access static information, such as bus schedules.
  • Kiosks: Kiosks are video monitors mounted on a stand-alone cabinet, in a wall, or on a counter-top. They may have input devices such as keypads, trackballs, or touch-screen displays. Kiosks may be located in places such as hotels, restaurants, airports, service stations, and retail establishments.

10.4 Advantages and Disadvantages of Various Methods of Information Dissemination

Table 10-3 describes the advantages and disadvantages of various methods of information dissemination.

Table 10-3. Advantages and Disadvantages of Methods of Information Dissemination

Method	Advantages	Disadvantages
Changeable Message Signs (CMS)	Various CMS technologies are available, giving good flexibility Provides information specific to the precise location of the driver Portable CMS can easily be deployed in the case of an incident, construction, or special events Information can be used by all drivers, no special equipment is needed	Most CMS only allow enough space for short messages with little detail May be distracting to drivers, and requires them to take their eyes off the roadway to read the sign.May cause accidents, and may cause delays if drivers slow down to read and to comprehend the message on the sign If a CMS is blank, drivers may assume it is disabled. If a CMS has a non-critical message, it may lose credibility
Highway Advisory Radio (HAR)	Doesn’t require any special equipment for driver. Virtually all cars have a radio Can give longer, more detailed information than CMS. Can be used at any location within the coverage area, rather than at fixed locations where a CMS happens to be located Information is received through a different sensory channel (audio), which reduces information overload received visually while driving.	Requires action on the part of the motorist—he or she must tune to the specific radio station. May be distracting, and many drivers do not bother to tune into HAR station Many drivers do not trust HAR and may prefer commercial radio. Requires an FCC license, and in many cities there may be very few available frequencies that will not interfere with existing radio stations A driver may miss the key part of the message and may have to listen again to the entire message When used on a surface street network, it is not practical to post HAR beacon signs at every intersection. Driver notification is more difficult than for freeways.
Cellular Telephone Hotlines	Allows drivers to access information specific to the road or region they are interested in. Can be used while driving	Only available to drivers with cell phones Use of cell phone while driving may cause distractions (this problem is mitigated somewhat by the use of hands free cell phones) May require a complex menu system for the driver May require driver to pay for cellular airtime Driver often inadvertently provides incorrect location information
Commercial Radio	Information is very easily available: virtually all cars have a radio, and most drivers have it on Drivers generally prefer commercial radio over HAR, and trust the information more	Traffic reports are only given during the times where they are normally scheduled. This may cause a major incident to be reported late or not at all, and may cause out of date information to be reported Only a very short period of time is allowed for traffic reports, which limits the amount of information that may be given There can be error in interpretation of information by broadcasters
Citizen Band (CB) Radio	Useful for a motorist-aid system Allows 2-way communication between driver and response agency	Most vehicles except for trucks and commercial vehicles are not equipped with CB radios
In-Vehicle Navigation Systems)	Travel information is more readily accessible to the driver (providing continuous access to current position, routing, and navigational information) Computer-generated navigational maps and displays are logical extensions of traditional forms of providing drivers with route guidance and navigation information	Visually based systems may cause driver distraction and information overload. Systems are limited to static route guidance only. (i.e. non-traffic related information unless an unusual level of surface street surveillance is provided)
Television	Convenient for pre-trip planning, drivers can watch the television before leaving	Not available while inside vehicle
Telephones	Can provide customized pre-trip planning information to drivers Can be used for dynamic ridesharing	Only a cellular phone can be used while in a vehicle. See “Cellular Phones” above for more information
Pagers	Can provide customized, real-time information	Can only give a very small amount of alpha-numeric information Only available to drivers who own pagers
Personal Data Assistants (PDAs)	Can give more detailed information than an alpha-numeric pager Two-way communication allows drivers to access information specific to their needs	Only available to drivers who own a PDA Dangerous to use while driving.
Computers (Internet)	Two-way communication allows drivers to access information specific to their needs Allows very detailed information	Usually not available while in-vehicle Not all drivers have a computer with an internet connection
Kiosks	Can give information tailored to a specific population, at a specific location	Not available while in vehicle Many kiosks are not located where they can be reached by their target audience and are not well used

Uses of Traveler Information Devices on Surface Streets

• Congestion: Almost any form of information dissemination can be used to give information on congestion on both freeways and surface streets. For example, a CMS can be used on a surface street either to give information on the surface street itself or information on an intersecting freeway. HAR, as well as other forms of media (such as internet or television or commercial radio) can give city-wide congestion information.
• Incidents: Information dissemination is also useful in the case of an incident on a surface street. A portable CMS may be deployed at the incident location to inform motorists. Portable CMS may also be used upstream of an incident to advise of a detour if road closures are involved. HAR, as well as other forms of media, could alert motorists of the incident.
• Construction: Similar to incidents, information dissemination is useful during construction activities. Like incidents, portable CMS, HAR, and other forms of media can alert drivers to the construction, and also advise of alternate routes. For an especially major construction project, an internet service or hotline can give up to date information on the status of construction, information on road closures, and travel time information.
• Route Guidance: A variety of different methods of information dissemination can be used to provide route guidance on surface streets. In-vehicle navigation systems (video display terminals, head up systems) can give customized, turn-by-turn route guidance information. A variety of internet services also can give turn-by-turn directions between two points. In many cities, CMS can be used on the surface street network to direct motorists to the best route to a destination such as a bridge or tunnel. Often, a hybrid sign, including both a static component and a changeable component (such as arrows) can be used for this purpose.
• Weather: Various forms of media, including HAR, can give motorists information relating to severe weather conditions, and how it affects driving, including road closures. Portable CMS can be used on surface streets to inform motorists of severe conditions, road closures, and alternate routes.
• Special Events: Portable CMS can be used to direct motorists to special events, to give parking information, and to give alternate routes to traffic wanting to avoid the area of the special event.
• Emergencies / Evacuation: In recent years, increased attention has been given to security issues. In the event of an emergency, such as a terrorist attack, various media forms, including HAR, as well as CMS can be used to alert motorists of evacuation routes, closed roads, and restricted roads.
• Parking: CMS or HAR can be used to alert drivers of which parking lots are closed or full, and the locations of alternate parking locations.
• Transit information: Internet services, PDAs, and kiosks are useful for information relating to public transit schedules. They can deliver both static information, as well as real-time information related to delays, schedule changes, and bus route diversions.

1. "What are Intelligent Transportation Systems." Hudson Valley Transportation Management Center (http://www.hudsonvalleytraveler.com/its.html).

2. "Manual on Uniform Traffic Control Devices." Federal Highway Administration, Washington DC, 2000.

3. Pline, J.L. (editor). "Traffic Engineering Handbook." 5th Edition. Institute of Transportation Engineers, Washington, DC, 2000.

4. Neudorff, L.G., J.E. Randall, R. Reiss, and R. Gordon. "Freeway Management and Operations Handbook." Federal Highway Administration Report No. FHWA-OP-04-003, Washington, DC, September 2003.