Photos of cars on freeway, speeding sign

Freeway Management and Operations Handbook

Chapter 13 – Information Dissemination
Page 3 of 3

13.2.11 Emerging Trends

As previously discussed, "511" telephone-based traveler information is still emerging as a trend through the Nation. Each implementation brings with it new lessons and different approaches. Amber Alerts

Another trend in traveler information relates to the use of traveler information devices to inform motorists of abducted children. The Amber Alert Plan Program is a voluntary program where law enforcement agencies partner with broadcasters to issue an urgent bulletin in the most serious child abduction cases. These bulletins notify the public about abductions of children. The USDOT recognizes the value of the Amber Plan Program and fully supports the State and local governments' choice to implement this program. (13)

Alerts of recent serious child abductions may be communicated through various means including radio and television stations, HAR, CMS, and other media. Under certain circumstances, using VMS to display child abduction messages as part of an Amber Plan Program has been determined to be consistent with current FHWA policy governing the use of VMS and the type of messages that are displayed. The FHWA, in fact, recently issued a policy memorandum that supports the use of CMS for Amber Alerts. This memorandum may be viewed at the following URL:

A key factor in the success of the Amber Plan Program is the need for public agencies to develop formal Amber Plan policies that include a sound set of procedures for calling an Amber Alert. If public agencies decide to display an Amber Alert or child abduction messages on a CMS, the FHWA has determined that this application is acceptable only if it is part of a well-established local Amber Plan Program, and public agencies have developed a formal policy that governs the operation and messages that are displayed on CMS. Care must be exercised to ensure that the message displayed does not exceed the reading and information processing capabilities of the motorists. Integrated Network of Transportation Information (INTI)

A recent initiative, primarily driven by ITS America, is the "Integrated Network of Transportation Information" (INTI). The creation of an INTI is one of the programmatic themes contained in the "National ITS Program Plan: A Ten-Year Vision" (14). As stated in that document, an Integrated Network of Transportation Information will:

  • "Create, operate, maintain and update the information management mechanisms to gather, analyze, coordinate, extrapolate, and store the data and interact with adjoining external systems. This will necessarily be done at multiple levels by a large number of organizations under consistent guidelines for information gathering, validating, sharing, and coordinating."
  • "Implement appropriate policies, procedures and security technologies to ensure that the system is secure and that only authorized stakeholders have access to data."

The INTI was the subject of a workshop entitled "INTI – Moving Toward and Integrated Network of Transportation Information: From Information to Integration", held in Houston, TX in February 2003. The INTI was presented at this workshop as consisting of three building blocks – gathering data, sharing data, and using data. Also presented were several key attributes and issues, including:

  • Implementation should not be heavily infrastructure-based; rather, the long-term path is heavily vehicle-based (but not exclusively) both on collection and delivery side. Travel time is key; weather information is also important. Program will not be Federally mandated (in whole) or controlled; although there may be Federal incentives and, likely, a Federal coordination role.
  • Both public and private innovation, commitment, and contribution will be required. It cannot be just a public or private sector initiative.

13.3 Implementation and Operational Considerations

13.3.1 CMS Messages

CMSs are one of the primary links a transportation agency has to the motoring public it serves. Improperly designed or operated CMS messages (e.g., displaying messages that are too long for motorists to read at prevailing highway speeds, or that are too complex or inappropriately designed leading to motorist confusion) can adversely affect both traffic flow and the transportation agency's credibility. The design and display of messages on CMSs introduce many challenges to transportation agencies and freeway practitioners. Recommendations to meet these challenges are presented in the Guidelines for Changeable Message Sign Messages Manual (Reference 5), which is a consolidation of the most current and best information on the design and display of effective CMS messages for incident and roadwork events.

Some of the more relevant issues identified in the Guidelines are briefly summarized below.

  • Efforts must be made to ensure that CMS messages are standardized and consistently applied throughout a state or region—The messages displayed must be "transparent" to travelers in the state or region. Therefore, messages need to be presented in a consistent manner and order based on motorists' expectancies.
  • Steps can be taken when developing CMS messages to enhance motorist understanding of messages—In developing messages, factors that enhance understanding of messages include the following:
    • Simplicity of words,
    • Brevity,
    • Standardized order of words,
    • Standardized order of message informational units,
    • Understood abbreviations when abbreviations are needed, and
    • Standardized applications of messages.

An efficient, brief, and to-the-point message is a good message. Just because there are spaces available on a CMS does not mean that all spaces should be used for a message.

  • CMS messages should be displayed and changed in a timely manner—The importance of timely display of CMS messages stems back to credibility. CMS operators do not always have all the information necessary to display messages that provide all of the details for motorists to make decisions. This is particularly true immediately after the operators are notified that an incident has occurred. Information should be displayed as quickly as it becomes available, recognizing that the CMS operator may have to change a message several times over the course of the event as new information becomes available or traffic conditions change.
  • Operating agencies should have written CMS policies and/or operational procedures—CMS message design and display should be predicated on CMS operational policies and procedures. Although an agency is more likely to have written operational procedures, most do not have written policies. Operational policies dictate some of the requirements for operational procedures.
  • CMS message objectives should be established and messages should be designed before CMSs are purchased—Too often, agencies purchase CMSs before signing objectives and messages are determined. The consequence is disappointment in the inability of the CMS system to display the appropriate messages because the sign does not have enough lines, and/or the line length is not long enough to display the desired messages. In addition, the CMSs have lower than expected target value and legibility for the environmental conditions present at the site.

A recommended procedure for determining the types of CMSs that will be acceptable for a given application is provided as summarized below. It should be noted that the nine steps of the procedure are interrelated and that the procedure is an iterative process.

  • Clearly establish the objectives of the CMS – The importance of setting signing objectives cannot be overemphasized because the objectives directly influence message content, format, length, and redundancy, and consequently, the size and placement of the CMS. When setting objectives, the agency must be specific in defining: What the problem is that is to be addressed with the CMS; Who is to be communicated with (audience); What type of driver response is desired; Where the change should take place; What degree of driver response is required; and How the CMS system will be operated.
  • Prepare the messages necessary to accomplish the objectives – The length of the messages will help define the character size, message line length, and number of message lines required on the CMS. It may be necessary to modify some of the messages to reduce their lengths as a result of conditions determined in subsequent steps.
  • Determine legibility distance required to allow motorists ample time to read and comprehend the messages.
  • Determine locations of the CMS that allows motorists ample distance to read, comprehend and react to the messages – The CMS must be placed such that the CMS and existing static signs form an integrated and compatible system of information.
  • Identify type and extent of localized constraints that might affect the legibility of the CMS – Field inspections are advisable to ensure that there are no physical obstructions due to bridges, sign structures, geometries, etc. that would adversely affect CMS legibility. In addition, field inspections will also help determine whether or not it is possible to actually install a CMS at the site. Obstruction problems would require that the agency either relocate the CMS or reduce the length of the messages.
  • Identify the environmental conditions under which the CMS will operate – Weather conditions such as snow, rain, etc. and other conditions such as blowing dust, heat, cold, etc. will have an effect on the sign's operation and will, in most cases affect the legibility of the messages. These environmental conditions should be made known to the manufacturer so that the best CMS performance characteristics can be achieved.
  • Determine the target value and legibility of candidate CMSs – An evaluation of the capabilities of the CMSs may dictate the need to reduce the message length or to require the manufacturer to modify the hardware and/or electronics to improve legibility.
  • Determine the costs of candidate CMSs.
  • Select the CMS that will allow the selected messages to be read under all environmental conditions within the cost constraints of the agency. CMS Credibility

Paramount to the message design and display, CMSs must provide timely, reliable, accurate and relevant information and they must be operated properly to be effective. Credibility is an extremely important consideration in properly operating a CMS system. Regardless of how well a message is designed, motorists will eventually come to distrust the signing system if the messages are not changed at the correct times and updated to reflect current traffic conditions. Each time the information displayed is disproved, the credibility of the system decreases. Eventually the messages are ignored and the CMS system is in jeopardy. There are at least eight reasons why message credibility suffers (5):

  • Information is inaccurate (e.g., no crash is observed when traffic passes by the location where an incident was displayed on a CMS).
  • Information is not current (e.g., the message is not consistent with current conditions).
  • Information is irrelevant to essentially all motorists using that facility.
  • Information is obvious by inspection, and hence, is redundant (e.g., displaying Heavy Congestion when motorists are driving bumper to bumper in peak traffic).
  • Information is repetitive (the message is the same each morning when motorists pass the sign). Displaying the same information on a CMS each day for recurrent congestion can result in many motorists ignoring the CMS after a time. When an important message is displayed that will impact their trip, the motorists may not read the message. Some agencies are even considering the use of flashing beacons on CMSs to attract the attention of motorists when important messages are displayed.
  • Information is trivial (e.g., Drive Carefully, Support Your Local Red Cross, time and temperature). Displaying trivial information can result in many motorists, particularly commuters, ignoring the messages that have no direct impact on their trips and consequently will begin ignoring the CMS. When an important message is displayed that will impact their trip, the motorists may not read the message.
  • Information is erroneous and can be easily checked and disproved. Traffic speeds and time to reach a destination are examples of information that can be easily disproved. Delay time is more difficult to disprove by motorists.
  • Messages are poorly designed. The information is poorly structured resulting in messages that are difficult to read and comprehend, or are confusing. The messages may also contain misspelled words. CMS Usage

Once a CMS system is installed, a question always arises concerning when messages should be displayed. There are two schools of thought:

  • Display messages only when unusual conditions exist on the freeway; or
  • Always display some sort of message regardless of whether or not unusual conditions exist on the freeway.

The Manual (5) subscribes to the former of the two approaches because of human factors principles and because of difficulties in designing messages when incidents actually occur during the peak periods. The second approach of always displaying a message leads to violation of the following two important human factors principles – specifically, don't tell drivers something they already know; and use the CMSs only when some response by drivers is required (i.e., change in speed, path, or route).

The Arizona DOT Guidelines (7) indicate, "CMS should be used whenever pertinent messages will assist motorists to make helpful decisions. If, however, a situation arises, which requires the usage of a specific CMS for more than one ongoing condition; the following priority criteria should be used for displaying messages, in the order listed.

  • Safety
  • Roadway Closure
  • Minor Traffic Impact
  • Pre-Warning (e.g., construction lane closures, blocking-incidents, and delay information.
  • Test
  • Public Service Information"

13.3.2 HAR Operations

While HAR is a viable traveler information system, its effectiveness is limited only by its operational application. How the messages are distributed and the equipment that distributes it is very important to a successful program.

The HAR can use either live messages, pre-selected taped messages, or synthesized messages based on information from an ITS traveler information database. The following issues are important in the design and implementation of an effective HAR system.

The audio quality, content, structure, presentation, and length of the advisory message are important parameters in providing an effective messaging system. Sound quality is affected by a number of different items: quality and sensitivity of the automobile receiver; quality of the transmission or control lines used to load the message; quality of the original recording when loaded to the transmitter controller or system controller; characteristics of the voice used to record the message; quality of the transmission and recording equipment; and the quality of the transmitter, antenna, and ground plane system. The only definitive way to ensure the quality of the transmission signal, and clarity and audibility of advisory messages, is by off-the-air monitoring. This type of monitoring involves receiving and monitoring the broadcast messages, using an AM radio receiver, in the same manner that a motorist would receive the messages. A routine monitoring program should be established that ensures all transmitters in the system are monitored off-the-air on a regular basis. Case-by-case and periodic monitoring of advisory messages should also be undertaken to ensure acceptable audio quality.

The message must be clear, concise, relevant, and easy for the motorist to understand. Because a motorist may begin hearing the advisory message at any point in the message, the message should consist of a sequence of independent phrases, so that the listener will not be confused by lack of information in the previous portion of the message. Slow, deliberate speech will provide greater comprehension of messages with detailed content. With traffic advisory messages, the motorists must receive the information before encountering the congested area.

Ideally, motorists should only receive messages relevant to the geographic area they are in or are about to enter; this mandates the need to separate broadcast areas. However, because radio wave propagation differs greatly depending on topography, atmospheric conditions and time-of-day, the potential for interference in overlapping radio coverage areas that use the same transmitting frequency can be significant. Overall systems design and final selection of transmission technologies need to account for these variances.

13.3.3 ATIS Business Planning

Agencies that are considering expanding their ATIS business beyond roadway devices to encompass web sites, partnerships with the private sector (ISP's), etc., need to address several issues – for example, what information will be distributed, to whom, how, potential revenue generation, restrictions, etc. Some of these issues are discussed below. Business Models

A variety of ATIS business models have been used in the U.S., with varied successes. At present, it is safe to say that no one model have proven reliably profitable. Much the same can be said for ATIS in other parts of the world, too. The ATLANTIC (A Thematic Long-term Approach to Networking for the Telematics and ITS Community) Project's ATIS subtask undertook a study of comparing current practices of ATIS, including business models, that have been tried in recent years in countries on both sides of the Atlantic Ocean – the three communities of ITS experts in Europe, Canada, and US. The significant results as well as the methodology for the comparative analysis are summarized below: (15)

  • Both Europe and North America need to have a complete information value chain for delivery of ATIS services. The information value chain (or information supply chain) for ATIS describes a complete system from data collection, data fusion, to data distribution. All the links in the system must be operative for ATIS service delivery. Service quality to end-users is only as good as the weakest link in the information supply chain.
  • Broadcast traveler information supported by advertisement has been proven to be viable. In fact, the broadcast of traffic information supported by advertisement has proven to be viable for years. It is a very viable revenue producing method. Perhaps the next question should be about market development, not about viable advertising revenue. In the US, the Metro Networks model of selling airtime to advertisers during radio traffic reports has been a success. However, given the conglomeration of services that has occurred over the past few years (i.e., Westwood One incorporating Shadow, Metro Networks, and Smart Routes), it could be questioned how viable the competitive broadcast market really is. It should be noted that ATIS is beyond traffic broadcast. ATIS will require a quantum change in data gathering methods, from qualitative "reportage" to quantified data-rich sources. Other models, such as advertising on websites, have not been very successful or profitable. For example, advertising on the SmarTraveler cable TV service was not successful in the US.
  • Public sector agencies should be prepared to underwrite all costs of specific information services they wish to provide. This is certainly true for information services free at the point of use and offered as a public service, such as Traveler Advisory Telephone Systems, Government Access Channel Traffic TV Systems, and Government Websites. It is also true for some public transportation information systems but not necessarily true for commercial, personalized subscription services and for wireless services to mobile and portable devices. There may be certain services (e.g., subscription-based services) that the public sector would offer only if partnered with another firm that would assume fiscal responsibility for the service. These types of services may be akin to "bells and whistles" in that they would not be deemed essential public services, but could still be very effective in meeting public policy goals. Thus, there may be some services that the private sector can provide, especially for niche markets such as commercial vehicles or business travelers. The public sector would have an interest in seeing these markets served but public support may not be required. In this case, public sector agencies might consider underwriting the costs of providing the framework necessary to enable those services to be provided, or proceed in partnership with the private sector. Public-Private Partnering

Some differences in philosophies between the public and private sectors must be realized, understood, and overcome. Typically the public sector, or the provider of the data, desires to disseminate the information to the widest possible audience, while the private sector's primary goal is profit-oriented, and the two philosophies must be synergized to realize the ultimate goal of each group. A January 2002 study for FHWA on the subject of sharing public data identified the following findings: (16)

  • Agencies have two major objectives in sharing their data with private sector and other public sector recipients: improving transportation operations through better interagency coordination and optimizing the use of the transportation system by providing information to travelers. Enhancing interagency coordination was the top-ranked motive for data sharing.
  • Even though their motives are different, public and private sectors are active participants in use of traveler information as a transportation management tool. Almost all agencies directly provide information to the public typically with VMS, HAR, kiosks, and interactive voice response telephones. Although agency data are a fundamental source, private providers generally need to enhance public data before they are marketable. The most common types of information provided are traffic and road conditions, incident information, and planned construction information. Transit data are generally less useful to private providers, and only a third of them report transit delay information.
  • Agencies that have data to share protect their interests by placing restrictions on access to data, but firms generally do not find these conditions to be onerous. Two or more conditions on access are common, the most frequent being acknowledgement of the agency as the source of the data when distributed to the public.
  • Formal policies on data sharing were reported by half the 34 surveyed agencies and several more have plans to issue one. The principal advantage of a formal policy is that it provides a process for handling requests for agency data.
  • In addressing the costs associated with the data sharing process, agencies frequently employ two or more cost recovery mechanisms in data sharing relationships. Most frequently agencies require the receiving party to cover its own cost, such as hardware, software and communications cost to connect to agency data sources. The second most popular mechanism involves a private firm sharing its "value-added" information with the agency.
  • The two most controversial topics in the private sector's relationships with agencies regarding agency data are revenue sharing and exclusivity. The idea of revenue sharing is optimistically viewed by many agencies, although in practice it has not had much success. The private sector tends to oppose revenue sharing either because of practical difficulties in administering it or because it violates the principle that public data should be available to all taxpayers for free.

There can be little doubt, then, that the private sector must be a full-fledged partner in deploying and managing traveler information dissemination systems (e.g., the INTI). Moreover, private sector participation will likely go beyond using, value-adding, and delivering public data; and also include the generation and collection of information. While this approach is appealing (and probably necessary), past experience has shown that it is not always an easy process. As noted above, there are several issues that must be addressed if effective partnerships are to be established for the collection of information, including:

  • Data ownership – When a private entity is involved in the collection of traffic flow information, it is important to establish ownership early in the process, so that the rights of each party to use, distribute, and/or sell the data are defined.
  • Exclusivity – Many public agencies are legally required to disseminate any data collected with public funds to all requesting organizations. An agency may therefore be prevented from giving exclusive rights to a private sector organization with which it has entered into a "surveillance" partnership, forcing the private sector partner to compete with other entities that have not made a similar investment.

13.4 Examples

13.4.1 511 Virginia

511 Virginia is a Virginia Department of Transportation (VDOT) service, contracted to Virginia Tech Transportation Institute (VTTI), who in turn has subcontracts and service contracts with additional parties, including Shenandoah Telecommunications (Shentel) and Tellme Networks, Inc.

The 511 Virginia service grew out of the Travel Shenandoah regional travel information service that was launched in July 2000, serving the primarily rural part of western Virginia. Situated along 150 miles of the Interstate 81 corridor, Travel Shenandoah covered 11 counties and one VDOT District – Staunton.

Before launching the 511 Virginia service, the coverage area was expanded to include the entire length of I-81 in Virginia and all major roadways in three VDOT Districts – Staunton, Salem and Bristol. Today, 511 Virginia serves 35 counties and a resident population of approximately 1.4 million people. Virginia was the first to offer services beyond traditional transportation-related information including information on food and lodging, tourism and attractions, and shopping. The information is provided via an interactive voice actuated system (no need to press buttons) via the 511 dialing code and also through a companion website,

In support of the service, VDOT has placed 58 roadside signs along I-81 and the intersecting Interstate approaches in the region to help promote the service. VDOT has also produced public service announcements, rack cards, and other promotional materials. The exact level of marketing to attract and maintain a high-volume, consistent user base is currently unknown. However, consistent marketing and brand awareness are critical to the success of 511 Virginia and 511 services nationwide. Therefore, all marketing materials produced will use the 511 Deployment Coalition developed and distributed 511 logo and usage guidelines.

13.4.2 AZTech

The AZTech™ Intelligent ™Transportation System (ITS) Model Deployment Initiative (MDI) is a seven-year project (two-year implementation and five-year operation) to develop an integrated Intelligent Transportation System for the Phoenix metropolitan area. AZTech™ is a unique transportation partnership of public agencies and private corporations who integrate travel and communication systems within the Phoenix metropolitan area. This partnership provides Arizona motorists with traveler information such as real-time traffic conditions, related road closures, and accidents. This information is provided through the use of live traffic cameras, variable message signs and through a large network of fiber optics and communications systems. In addition to the ATIS element, other major components of AZTech™ include regional operations partnership, smart corridors, incident management, system integration, emergency management, data archiving, special event management, regional procurement, and telecommunications (20).

AZTech™ has been successful in building a unique ATIS public-private business model. The Advanced Traveler Information System business model provides the structure for Maricopa County's regional transportation partnership. Bridging the gap between public and private businesses, this partnership enables the private sector to operate a self-sustaining automated traveler information system encompassing state-of-the-art technology.

AZTech™ has finished both Phase 1 and Phase II public-private partnership projects as follows:

  • Phase I of the AZTech™ project involved utilizing prominent internet portals, such as MSN and MapQuest, to disseminate information. Personalized traveler information was also provided to commuters utilizing devices such as PDA's and in-vehicle services through GM Onstar.
  • Phase II of the AZTech™ project involved increasing its Internet capabilities, as well as setting up notifications to be distributed by fax and through digital TV. Additionally, through one of its partners, AZTech™'s was able to set up real-time traveler information, including travel time, for commercial vehicle operations. Another AZTech™ partner provided traveler information on in-vehicle devices.

The business model allows AZTech™ to participate in the fusion of better traffic data. Both private firms and public companies add value to data collected by and disseminated from AZTech, resulting in better information for all travelers. Proof that this business model has tangible benefits can be found in AZTech™'s involvement in researching and testing the latest technical achievements. Recently, AZTech™ performed a production test of a new personalized traffic service. Using wireless capabilities, real-time travel information was disseminated to users throughout the Phoenix metropolitan area. AZTech™ partners created personal trip profiles on the ATIS private partner service. Alerts were available for dissemination to cellular phone, WAP phone, PDA, pager, fax and email. The user then customized information by entering details such as:

  • Personalized freeway route;
  • Times of day to activate notification; and
  • Level of severity of activated alert.

The user specified the preferred device that was to receive traffic alerts. Any activity reported on a specific route, including incidents, recurring and non-recurring congestion, and construction, was then automatically distributed to the user's specified device.

Another successful outcome of the public-private partnership initiated by AZTech™ has been the introduction of a dedicated traffic cable channel in four jurisdictions. The cable television channels provide information regarding travel conditions through data fusion from the freeway management system at peak travel hours.

With the launch of Phase III, AZTech™ has entered a new era of travel information services. New services include travel time prediction, dissemination, and enhanced Internet services. Additional information can be found on the AZTech™ website at

13.5 References

1. Keever, D. et al; "Data Fusion for Delivering Advanced Traveler Information System (ATIS) Services"; Working Draft; SAIC; November 2002.

2. Dudek, C.L. Guidelines on the Use of Changeable Message Signs. Report No. FHWATS-90-043. FHWA, U.S. Department of Transportation, Washington, DC, May 1991.

3. Wunderlich, K. et al; "On-Time Reliability Impacts of Advanced Traveler Information Services (ATIS): Washington, DC Case Study"; FHWA; January 2001,

4. Dudek, C.L. and Huchingson, R.D. Manual on Real-Time Motorist Information Displays. Report No. FHWA-IP-86-016. FHWA, U.S. Department of Transportation, Washington, DC, August 1986.

5. Dudek, Conrad L., "Guidelines for Changeable Message Sign Messages", Report No. FHWA-OP-03-070. FHWA, Department of Transportation, Washington, DC, December 2002.

6. Dudek, C.L. Changeable Message Signs. NCHRP Synthesis of Highway Practice No. 61. TRB, National Research Council, Washington, DC, 1979.

7. Arizona Department of Transportation / Transportation Technology Group; "Guidelines on the Use of Permanent Variable Message Signs"; March 2002

8. ITS Standards advisory; Dynamic Message Signs (DMS); January 2003 Advisory No. 1

9. Specification Guide for Procurement of NTCIP-compliant Dynamic Message Signs (DMS); FHWA Joint Program Office; October 2002

10. Schuman, R. and Sherer, E. "511" "101";, 511 Deployment Conference, Scottsdale, Arizona, March 2002.

11. "Resource 511" website,

12. 511 Deployment Coalition, "511 America's Travel Information Number, Implementation Guidelines for Launching 511 Services", version 1.1, June 2002.

13. FHWA website,

14. ITS National Program Plan; ITS America

15. Chen, K. ATIS Practices in Europe and North America – A Report on Comparative Analysis. Contract No. DTFH61-96-C-00077. USDOT, Washington, DC, October 2002.

16. Zimmerman, C., Mallett, W., Raman, M., and Roberts, C. Sharing Data for Traveler Information: Practices and Policies of Public Agencies. Contract No. DTFH61-96-C-00077. USDOT, Washington, DC, January 2002.

17. 511 Deployment Coalition, "511 Brochure"

18. Schuman, R. and Sherer, A. ATIS U.S. Business Models Review. USDOT, Washington, DC, November 2001.

19. The ITS National Architecture, Documentation – Version 4.0, April 2002

20. AZTech web site,

21. "Manual on Uniform Traffic Control Devices" (MUTCD) 2000, Millenium Edition, Institute of Transportation Engineers, Washington, D.C., 2001.