Planning, designing, and operating integrated transportation management systems (ITMS) is a complex undertaking involving multiple agencies and jurisdictions. In order to respond to the numerous transportation and environmental issues facing metropolitan areas today, these systems are being designed and developed to include not only the traditional traffic and roadway management functions, but also provisions for emergency services, transit and other high-occupancy vehicles, as well as supporting travel demand management (TDM) strategies. While these functions address many of the modes currently operating in urban environments, they do not include all of the transportation components critical to the movement of both people and goods necessary to maintain the economic health and vitality of metropolitan areas. For ITMS to be a truly integrated system, and to move from a focus primarily on traffic management to a more global view of transportation management, consideration must be given to the inclusion of other modes and functions. These include toll facilities, bicycle and pedestrian systems, commercial vehicles and private operators, parking facilities, disaster response teams, railroads, and land-side access to ferries, airports, ports, and railroads. It is only through the incorporation of these modes and functions that a truly integrated system will emerge.

The integration of these modes and functions into ITMS is not an easy process, however. Numerous technical and institutional issues will need to be addressed to help ensure that these systems are developed and operated with a multimodal focus. This resource paper is intended to help foster, enhance, and expand on the discussion of the components to be included in multimodal integrated transportation management systems, potential issues and opportunities associated with this approach, and possible implementation strategies. As such, it builds on the experiences with existing transportation management systems, the previous ITMS Symposium sponsored by the Transportation Research Board (1), and the activities of other groups. It takes a fresh look, however, at the modes and functions necessary to help ensure the development and operation of multimodal ITMS to meet the complex transportation needs in metropolitan areas.

To accomplish this objective, the paper is divided into four sections following this introduction. The next section presents the concept of a multimodal ITMS and describes the various components to be included in such a system. This is followed by a discussion of potential technical and institutional issues that may emerge in planning, designing, funding, and operating multimodal ITMS. Opportunities for incorporating a multimodal focus into ITMS are also described. The next section outlines different implementation strategies that may be considered for multimodal ITMS. The approaches discussed provide for different levels of involvement, coordination, and control by the agencies and groups involved in multimodal ITMS. The paper concludes with a summary of the major topics covered and the identification of areas for further research. Examples of current applications and suggestions for possible approaches are provided throughout the paper.

A number of terms have been used over the last 25 years to describe traffic management systems and centers. The first systems developed in the 1960s and 1970s focused primarily on monitoring and managing traffic conditions on freeways. The intent of these systems was to increase the roadway capacity, increase travel speeds, reduce accidents, and improve air quality levels ². Most of the systems initiated in the 1960s, 1970s, and early 1980s—including those in Chicago, Minneapolis-St. Paul, Seattle, Los Angeles, and Northern Virginia—used the general terminology of traffic management systems and centers (TMS and TMC).

Over the years, existing and new transportation management systems have become much more complex and sophisticated. Intelligent transportation systems (ITS) and other advanced technologies are being used to expand the monitoring, detection, and response capabilities of these systems. Further, some systems encompass not only freeways, but also entrance ramps and adjacent roadways. The focus of transportation management systems has also been expanded in some cases to include other modes, such as transit and emergency services. The current terms used to describe these systems include advanced transportation management systems (ATMS) and integrated traffic management systems (ITMS).

A number of elements are key to defining ATMS and ITMS. The intent of both is to maximize the productivity and efficiency of the surface transportation system through better management of the existing infrastructure, while at the same time enhancing safety, mobility, accessibility, and the environment. The use of ITS and other advanced technologies is critical to accomplishing these goals. The inclusion of all surface transportation modes and functions is also crucial. These include not only the freeway and roadway system that has been the focus of most existing systems, but also toll, bicycle, pedestrian, transit, HOV, and parking facilities; TDM; commercial vehicles; disaster response teams; railroads; and land-side access to ferries, airports, ports, and railroads.

Figure 1 illustrates the various components that should be considered in a multimodal integrated transportation management system. ITMS should encompass the freeway network, the arterial street system, toll facilities, HOV lanes, transit operations and facilities, bicycle lanes, pedestrian paths, parking facilities, and railroads. ITMS should also facilitate incident detection and management, emergency services, special event management, TDM, disaster response teams, commercial vehicles and private carriers, and access to ferries, airports, ports, and railroads. Many of these elements are interdependent or overlapping. Each of these components is briefly described next. Examples are provided where these elements have been incorporated into current systems and suggestions on potential applications are identified. The examples are not intended to be all encompassing. Rather, they are provided to illustrate the scope of existing and future approaches.

The historic focus of most transportation management systems has been on monitoring and managing the freeway network. This has included surveillance of the freeway main lanes, entrance ramps and ramp meters, and freeway-to-freeway connections. In many metropolitan areas, these systems were initiated in one or two heavily congested freeway corridors and then expanded to encompass most or all of the freeway network. A wide range of technologies are currently used to monitor and manage traffic conditions on freeways. These include loop detectors, closed circuit televisions, video imaging, changeable message signs, highway advisory radio, and other advanced technologies.

Freeway traffic management systems are in operation or under development in most of the major metropolitan areas in the United States and Canada ^1,3. Further, similar systems are in use or in the planning stages in many cities in Europe and other parts of the world ⁴. The benefits from freeway traffic management systems have been well documented. For example, the traffic management system on I-35W in Minneapolis resulted in a 35 percent increase in peak-period speeds and a 38 percent reduction in peak-period accidents ⁵.

As noted above, most transportation management systems have focused on the freeway network in major metropolitan areas. Less emphasis has been given to including arterial streets in these systems. Examples do exist, however, of the incorporation of adjacent streets and other arterials into transportation management systems. One of these is the transportation management system for the SMART Corridor Project in the Santa Monica Freeway Corridor in Los Angeles, which includes both the freeway and five parallel arterials. Further, the system under development in Orange County, California, will encompass both the freeway and the super street network ¹.

Ensuring that ITMS cover both freeways and major arterials will be important in the future as travel demand continues to grow. Since conditions on one element of the roadway system will effect conditions on other components, ITMS should encompass all major roadway segments in a metropolitan area. This will be especially important as more sophisticated ITS technologies and route diversion/management strategies are employed. These techniques will not be successful if traffic congestion is simply moved from one facility to another. Coordinating arterial traffic signals represents an important element of this integration.

Toll facilities—including roads, bridges, and tunnels—represent critical components of the transportation system in many metropolitan areas. Currently, toll facilities in a few areas are covered by transportation management systems. These include the San Francisco-Oakland Bay Bridge and the New Jersey Turnpike. In addition, the transportation management system under development in the Houston area will include the Hardy and Sam Houston toll roads.

Like the arterial street network, it is important that toll roads, bridges, and tunnels be included in ITMS. Given that these facilities provide critical links for the movement of both people and goods in many urban areas, it is appropriate that incident detection and management capabilities be provided. In addition, toll facilities may be integral components for diversion and other management strategies. Further, many toll facilities are utilizing electronic toll collection (ETC). Linking ETC systems into ITMS could provide additional benefits to both the toll facilities and to the ITMS.

A major traditional function of ITMS is the detection and management of incidents and accidents on the roadway system. The early detection and response to incidents can have a significant impact on maintaining the integrity of the roadway system. It has been estimated that every minute an accident blocks a freeway results in ten minutes of delay for oncoming traffic. Identifying that an accident or incident has occurred, dispatching the appropriate emergency or wrecking services, and taking a proactive approach to managing traffic will continue to be major functions for ITMS on all elements and for all modes of the surface transportation system.

Emergency services play a critical role in responding to the incidents and accidents detected through ITMS. Police, highway patrols, emergency medical services (EMS), highway helper programs, and wrecker services are all used in different areas to clear accidents and to help address medical needs. In some cases, these services are notified or dispatched by the transportation management center. In keeping with the current focus of transportation management systems, emergency services usually deal only with incidents on the freeway or major roadway system.

A broader perspective is needed for the inclusion of emergency services into ITMS. This vision should build on the current role described above, but should be expanded to encompass interactive links to police, fire, EMS, and other emergency services. For example, emergency services responding to a problem not associated with the roadway system would benefit from knowing that an incident or accident is blocking the normal travel route. Providing information on the fastest and least congested travel path could mean the difference between life and death in many situations. As discussed later, adding information on the status of railroad grade crossings could also be critical to emergency services in many areas.

Existing systems have been used to help manage transportation during special events. These include major one-time only events such as the 1984 Olympics in Los Angeles and the 1992 Olympic Sports Festival in the Minneapolis-St. Paul area. Coordinating and managing transportation for the 1996 Olympics in Atlanta is also being planned as part of the Atlanta Transportation Management Center currently under development. Further, existing systems are being used to help manage ongoing events, such as college and professional sporting events. For example, the Houston system is used to help with events at the Astrodome, the TMC in Minneapolis assists with traffic management for the Metrodome, and systems in Orange County and Anaheim help manage traffic for Anaheim Stadium and the many attractions in the area.

ITMS represents the logical focal point for managing all of the transportation demands for special events. A truly integrated system could coordinate and manage automobile traffic, regular transit services and special shuttle services, on-site and remote parking facilities, bicycle and pedestrian traffic, and emergency services. Further, ITMS in conjunction with special lanes and facilities, could be used to give priority to HOVs. This approach could help encourage greater use of these modes to further reduce traffic congestion.

Currently, some 52 HOV facilities are in operation in 22 metropolitan areas in North America ⁶. HOV lanes represent one approach being used in these areas to increase the person-movement, rather than vehicle-movement, capacity of congested travel corridors. A number of these facilities are included in existing transportation management systems. For example, HOV lanes on freeways in Houston, Minneapolis, Seattle, San Francisco, Los Angeles, Orange County, San Diego, and the Northern Virginia/Washington D.C. area are covered by transportation management systems. In addition, HOV by-pass ramps at freeway entrances are monitored on some of these facilities. In all of these cases, the same types of surveillance, incident detection, and response capabilities provided for the general-purpose freeway lanes are also provided on the HOV facilities.

Including HOV facilities in ITMS is logical given the important role they play in helping to manage congestion in major travel corridors. HOV lanes also represent a vital component of incident management, response, and diversion strategies. Further, ITMS should be expanded to cover not only freeway HOV facilities, as noted in the above examples, but also HOV lanes in separate rights-of-way and on arterial street. This will assist in maximizing the efficiency of the existing surface transportation system. Consideration should also be given to management techniques that maintain and enhance the integrity of HOV facilities and techniques to encourage greater utilization of all types of HOVs.

A few examples exist of the inclusion of transit services and facilities into transportation management systems. The HOV facilities described previously provide one illustration of this. In some cases, such as the El Monte Busway in Los Angeles and the I-394 HOV lanes in Minneapolis, the surveillance and monitoring activities extend to park-and-ride lots and transit stations. The role and participation of transit agencies in transportation management systems and ITMS has been, and continues to be, mixed, however. Historically, transportation management systems have been planned, designed, and operated by state departments of transportation or other highway agencies. Transit agencies have often had little or no involvement.

This trend seems to be changing, however, and there are recent examples of transit agencies actively participating in planning and operating transportation management systems. The Metropolitan Transit Authority of Harris County (METRO) is taking the lead, in cooperation with the Texas Department of Transportation (TxDOT), in the design and construction of the new Greater Houston Traffic and Emergency Management Center. In San Antonio, VIA Metropolitan Transit Authority plans to locate their dispatching functions in TxDOT's new advanced traffic management center. The ATMS being developed by the Montgomery County Department of Transportation will incorporate transit dispatching and operations ⁷. The transportation management system in Seattle also includes links to King County Metro.

Incorporating additional transit functions into ITMS represents a critical component of a multimodal focus. Transit systems can benefit from this integration through real-time information on roadway conditions, travel times, and incidents and accidents. Transit vehicles can then be diverted around trouble spots, improving on-time performance, schedule adherence, and service efficiency. Transit vehicles equipped with automatic vehicle location (AVL) systems may also be able to act as traffic probes, providing information on traffic conditions on arterial streets and freeways to the ITMS. Approaches to integrating transit into ATMS are being explored as part of the ITS Research Center of Excellence at Texas A&M University.

Only a limited number of examples exist of bicycle or pedestrian facilities being integrated into ITMS. The pedestrian and bicycle paths on the I-90 tunnels in Seattle are monitored by the Washington State Department of Transportation TSMC. In Minneapolis, the pedestrian bridge across I-94 linking the Walker Sculpture Garden with Loring Park is monitored by the Minnesota Department of Transportation (Mn/DOT) transportation management center. Given the growing interest in many areas in the use of bicycle and pedestrian projects to serve both commute and recreational trips, it is appropriate to include them in ITMS. The nature and extent of this coverage should be matched to the facilities, climate, and geography of different areas. For example, including the skywalk and tunnel systems found in many downtown areas into ITMS may be a logical connection, especially where these systems are used to help distribute passengers from transit services or remote parking facilities. Further, including bicycle and pedestrian paths in ITMS would greatly enhance the safety and security of these facilities.

Travel Demand Management (TDM) and Transportation Control Measures (TCMs) are being planned and implemented in many areas to address concerns over increasing traffic congestion, declining mobility, and environmental concerns, as well as to respond to specific requirements of the Clean Air Act Amendments of 1990. TDM and TCM programs focus on increasing the use of HOVs, spreading travel into less congested time periods, and removing trips all together from the transportation system. Coordinating these activities with transportation management systems and incorporating them into ITMS will be critical to their success. This process has already begun in some areas. For example, providing by-pass lanes for HOVs at freeway entrance ramps and initiating express buses on the freeway were major components of the initial traffic management system on I-35W in Minneapolis. There appear to be numerous opportunities to expand the coordination between TDM/TCM programs and ITMS, however. Fully incorporating TDM/TCM programs into ITMS represents a critical component to the multimodal focus and the ability to address the traffic, mobility, and environmental concerns in metropolitan areas.

Currently, parking lots and parking garages are not covered in most transportation management systems in the United States, although examples do exist in Europe. The few exceptions to this focus on park-and-ride lots associated with freeway HOV lanes. In some cases, surveillance is provided at these facilities and at adjacent transit centers. Further, the direct access connections provided from the I-394 HOV lanes into the parking garages on the edge of downtown Minneapolis are monitored as part of the Mn/DOT transportation management center.

Parking lots and garages should be incorporated more extensively into ITMS, however, based the importance of these facilities to commuters and travelers. The inclusion of parking lots and garages in ITMS would have a number of benefits. First, the monitoring and surveillance of these facilities would enhance the safety and security of users. Second, real-time information on the availability of spaces, as is done in some European cities, could be provided to travelers well in advance of the different facilities. This would help reduce the need for drivers to circle looking for parking and would reduce air pollution generated from these activities. Including parking facilities in ITMS would also assist with special event management and could be used to support TDM and TCM programs focused on providing discounted parking rates or preferential parking locations for HOVs.

Transportation management systems have played important roles in helping to respond to major disasters. Two recent examples are the use of the systems and control centers in Los Angeles and San Francisco to coordinate the response to the damage caused by major earthquakes. Incorporating the ability to accommodate disaster response teams into ITMS should be considered in all areas. This is especially critical, however, in those areas susceptible to natural and man-made disasters. These include areas prone to earthquakes, hurricanes, tornados, flooding, and major snow storms. Further, areas with high risk industries or facilities, such as petrochemical plants, pipelines, nuclear power plants, and hazardous wastes, should consider the need for disaster response teams in the ITMS center. ITMS represents the logical approach to coordinated traffic management, evacuation, emergency services, and other functions necessary to respond to natural and man-made disasters.

Existing transportation management systems monitor commercial vehicles as part of the general traffic flow. Special services or additional activities focused on commercial operators are not provided in most cases, however. A number of approaches could be used to integrate commercial vehicles more fully into ITMS, benefiting all groups. For example, providing real-time information on traffic conditions to commercial operators could help in planning travel routes and schedules. Coordinating the permitting and state inspection processes with ITMS may also be possible. Many of the ITS Commercial Vehicle Operation (CVO) applications focus on improving the permitting process among the different states. ITMS could help facilitate these activities. Commercial vehicles could also act as traffic probes, providing information on conditions on the roadway system. Finally, as discussed in more detail in the last element in this section, specific information could be provided to commercial vehicles accessing major intermodal facilities, such as ports, airports, and railroads.

Railroads operate in most urban areas, providing an important means for transporting commodities and people. To date, railroads have not been included in traffic management systems. There are a number of reasons why railroads should be included in ITMS. First, although railroads operate in exclusive rights-of-way, at-grade railroad crossings are found in many areas. The movement of trains through these at-grade crossings can have a significant impact on traffic, especially during peak-periods. Second, the potential for accidents involving automobiles, buses, commercial vehicles, and trains exists at any crossing. Third, derailments or other problems may occur along rail lines. These situations may be further complicated if noxious or hazardous materials are being transported by the railroads.

As a result, railroads should be incorporated into multimodal ITMS. Coordinating ITMS and the advanced train control systems (ATCS) operated by many railroads could benefit numerous groups. Better managing the timing of trains with other element of the surface transportation would benefit the traveling public. For example, the railroad lines located adjacent to the I-10 West Freeway in Houston significantly impact traffic in the corridor. Enhancing coordination among the railroad, the local street and signal system, and the freeway would enhance travel in the corridor. The safety of motorist, the railroads, and residents in the area could also be enhanced. Possible approaches to integrating railroads into ATMS are being examined in one of the research projects being conducted by the ITS Research Center of Excellence at Texas A&M University.

Access to Ferries, Airports, Ports, and Railroads

As discussed previously, ITMS could play an important role in managing the access to ferries, airports, ports, and railroad terminals by both commercial operators and the general public. Providing real-time information on the status of roadways leading to these facilities is an obvious approach that would have significant benefits to all groups. This could include providing information on travel times, travel speeds, and alternate routes. To be effective, however, a two way flow of information is needed. This would involve providing information on the status of operations at these facilities to the appropriate groups. For example, truckers could better manage their schedules if they were aware of delays or long lines to unload or load their cargo at a port facility. Further, travelers could be informed if ferry or airplane arrivals and departures have been delayed due to weather or other situations, relieving anxiety about missing connections.

A number of issues may be associated with planning, designing, funding, and operating a multimodal ITMS which incorporates all of the modes and functions described previously. In general, the types of issues which might be encountered can be divided into two groups; those that deal with technical concerns and those focused on institutional problems. Technical issues can be further categorized into the system architecture requirements and the technologies utilized by different groups, functional integration, and location and communication. Agency roles and responsibilities, funding, and legal issues represent some of the more important institutional issues which might be encountered. Each of these issues is described briefly in this section, along with approaches and opportunities that might help overcome them. Although many of these issues are similar to those involved with the development of any transportation management system or related project, the multimodal focus of ITMS adds complexity and may make it more difficult to resolve some problems.

A wide range of technologies are being utilized in existing transportation management systems. These include loop detectors, closed circuit television, video imaging, changeable message signs, highway advisory radio, and other technologies. Further, research and development activities, operational tests, and early deployment projects are focusing on the use of ITS and other advanced technologies to enhance the incident detection and response capabilities, as well as the information sharing capabilities, of ATMS. The key technical issues which may be encountered in planning, designing, and operating a multimodal ITMS are described next.

System Architecture Requirements and Technologies Utilized

A variety of technologies are being used in existing transportation management systems and additional advanced technologies are being developed and tested. New technologies are also being utilized with the other modes described previously. For example, many transit agencies are implementing automatic vehicle location (AVL) systems to help monitor the location of buses. Advanced train control systems (ATCS) are used by railroads for similar train location functions. Police, fire, and EMS also use a wide range of technologies to support their functions.

Ensuring that the technologies utilized by the different modes and groups are compatible will be critical to realizing the goal of a multimodal ITMS. Developing a system architecture that will incorporate all of these modes and functions can help in this effort. A system architecture provides a framework that identifies how the various system components interact and work together to achieve the overall goals of the project. It describes the operation of the system, the functions of each component, the information exchange between the various components, and helps to identify the need for critical standards ⁸. A process is currently underway to develop a national ITS system architecture. This effort, which is being funded by the United States Department of Transportation, should help address many of the potential technology issues associated with the development of a multimodal ITMS.

Even with the adoption of a common system architecture, additional steps will still be needed to develop the design of a specific ITMS and to integrate all of the necessary functions for the different modes. Thus, a number of issues will need to be addressed with the system design and functional integration of a multimodal ITMS. Elements that may need to be examined include the integration of different technologies, designing decision support systems, modeling and simulation capabilities, database development and management, software design and development, and data and system reliability. The issues and opportunities associated with system design and functional integration may be different in those areas with existing ITMS and those developing new systems.

The last major technical issue area relates to the actual location of the different components of the system and the communication links between the various modes and elements of an ITMS. Establishing the communication network and the links among the different functions and organizations represent critical elements in the development of an ITMS. Issues may arise over the compatibility of technologies used by different modes, information processing procedures, and system reliability. Communication technologies are evolving rapidly and ensuring that the appropriate technologies are utilized will be important.

Further, the issue of location will need to be addressed. A number of alternative location scenarios could be employed. For example, a central control facility could be used, with all the modes and functions located in the same building. Another option would be to utilize multiple sites, with information and control shared through the use of advanced communication networks. Various combinations of these alternatives could also be utilized, with both a central control center and communication links into individual agencies at remote locations.

Institutional issues have been identified as potential impediments with many types of programs, including transportation projects. For example, institutional issues associated with transit joint development projects ⁹, HOV facilities ¹⁰, and ITS operational tests ¹¹ have all been documented. It has often been suggested that the institutional issues associated with these and other projects are more difficult to address and overcome than the technical issues. Three of the major institutional issues that may be encountered with a multimodal ITMS are described next. Possible approaches for address these concerns are also outlined.

The development and operation of an ITMS which incorporates all of the modes and functions described in this paper will require the involvement of numerous public agencies and private businesses. Coordinating the activities of these diverse groups will not be an easy process. Numerous issues may emerge relating to the roles and responsibilities of the different public and private organizations. In many cases, simply reaching an agreement to develop a multimodal ITMS will be a major accomplishment. Other potential issues include sorting out the responsibilities of the different groups, establishing working relationships among organizations that have not worked together before, selecting a lead agency and project manager, establishing a process for resolving conflicts, and coordinating the activities of the various agencies and businesses.

The sheer number of agencies and organizations that need to be involved in a multimodal ITMS may represent a major challenge. Historically, state departments of transportation have been responsible for the development and operation of most transportation management systems. Other groups, such as transit agencies, police, and other emergency services, have become more involved recently in many areas. The inclusion of the modes and functions illustrated in Figure 1 will necessitate the involvement of even more public agencies and private groups. These may include toll authorities, railroads, airports, ports, commercial operators, local governments, police, fire, EMS, state and national disaster relief agencies, parking authorities and private parking facilities, special event organizers, and park agencies.

Getting these groups to work together and obtaining agreement on a common approach represent issues that may be encountered very early in the planning process. Thus, establishing the roles and responsibilities of the different groups represents a critical step. This can be difficult even with groups that have traditionally worked together, which is not the case with most of the organizations noted above. The mix of public and private groups makes the situation even more complex. Agencies may use different procedures, and the organizational cultures may vary greatly. Further, uncertainty or mistrust may exist among various groups. Overcoming these concerns will be a critical step in the development of a multimodal ITMS.

Issues may also arise in the selection of a lead agency and a project manager. Although multiple groups will need to be involved for ITMS to be successful, most projects have one agency or group with overall responsibility. Studies of other transportation improvements have pointed out the importance of both a lead agency and a strong project manager. As noted previously, the state department of transportation has usually taken the lead in the development of existing transportation management systems. They may also be the appropriate lead agency in a multimodal ITMS. Creating a new organization, charged only with developing and operating the ITMS, represents another possible approach. Still another approach is to establish a multi-agency group, charged with coordinating the activities of all groups. The use of combinations of these different approaches is also possible.

Studies of HOV facilities and ITS operational tests have also pointed out the importance of support from top management and having a project champion to the success of a project (10,11). Strong and visible support from the top management of all organizations will be critical to the success of a multimodal ITMS. In addition, a project champion can greatly enhance the success of any venture, including ITMS. Key characteristics for a project champion, which may be either an individual or a small group, include being in a position of authority, an ability to influence the process, being respected by others, and a willingness to take risks. The development of a multimodal ITMS provides the opportunity to maximize the resources of all groups.

Obtaining adequate funding for any transportation project is often a major concern. Most significant highway and transit projects are funded through a combination of federal, state, and local funds. Identifying potential funding sources, developing a financing plan, obtaining necessary approvals, securing the funds, and carrying out the financing program, represent major steps associated with any project. These steps are not easy even with relatively simple projects and become even more complex with a multimodal ITMS.

For example, the multiple agencies and groups described previously may all be participating in funding. The multiple funding sources available for ITMS provides a real opportunity. The mixing of funds from multiple federal, state, and local agencies may result in a complex grant application process, however, and may complicate grants management. Adding private funding sources to this mix may further complicate the situation. Developing a financing plan for a multimodal ITMS will require not only special skills, but also the close cooperation and coordination of the various groups involved.

The increased complexity of the financing approach needed for a multimodal ITMS may lengthen the project development and project implementation time periods. For example, funding and application cycles may differ between various programs and agencies. Obtaining approvals from the multiple federal, state, and local agencies involved in ITMS may require more time than if just one or two agencies were involved. Adding private funding sources into this may further lengthen the time needed to secure the financing needed for a multimodal ITMS.

Although the involvement of multiple public sector agencies and private businesses adds to the complexity of funding a multimodal ITMS, it also creates a number of opportunities. For example, it may be possible to spread the costs associated with the development and operation of the ITMS out among more groups, lessening the financial burden to any one agency. Further, the numerous groups involved increases the opportunity to leverage funding from multiple sources. Private funds may be used to match public funding, increasing the total amount available for the project.

Recent activities at the federal level may afford further opportunities. The Intermodal Transportation Surface Efficiency Act (ISTEA) of 1991 provides new programs for funding ITS, including those related to ATMS and ITMS, and allows greater flexibility in the use of different program funds to respond to locally identified needs. The ISTEA established a new research program to promote the development and deployment of ITS and other advanced technologies. Numerous activities related to ITS are underway through the coordinated efforts of federal, state, and local agencies, private businesses, national laboratory, university research institutes, and other groups. These efforts, as well as the increased flexibility offered by the ISTEA, may provide numerous opportunities for areas interested in developing multimodal ITMS.

A number of legal issues may need to be addressed in the development and operation of multimodal ITMS. Potential legal issues include ensuring that agencies posses the necessary authority to implement the various provision of ITMS, liability and insurance questions, and privacy concerns. Each of these represent complex issues which should be examined early in the planning process.

The various agencies responsible for planning, designing, funding, constructing, and operating a multimodal ITMS must have the legal authority to undertake all the necessary functions and activities. These may include the ability to enter into interagency agreements and contracts with private business, purchase property and equipment, construct and maintain buildings and equipment, and own and operate the various elements of the ITMS. The diverse public and private sector groups involved in a multimodal ITMS adds to the complexity of accomplishing all of these functions. Changes in enabling legislation or other laws may be necessary to allow different agencies and organizations to fulfill all of these activities.

In order to address many of these concerns, some areas have established new organizations charged with the responsibility of planning and operating ITMS. Two examples of this approach are the Greater Houston Traffic and Emergency Management Center and TRANSCOM in the New York and New Jersey area. More information on the approaches used in these areas are provided in other resources papers.

Other potential legal issues relate to liability and insurance concerns. Problems in these areas may arise in response to actions taken by individuals in response to the information provided by the ITMS. For example, liability and insurance issues may arise if there is an accident or property damage resulting from traffic being diverted from a freeway onto an arterial street. In another possible example, liability concerns may arise in the routing of emergency vehicles if the response time is deemed not fast enough by an injured party.

A last major legal issue that may arise relates to privacy. ITMS will be able to monitor and track a wide range of information, including the location of private automobiles, and thus individuals. How this information is used, especially related to police and law enforcement activities as well as situations that individuals may feel invade their privacy, will need to be addressed.

There are a number of approaches that may be used to plan, design, implement, and operate a multimodal ITMS. Examples of some of these techniques are being examined in more detail in other resource papers. Possible approaches include expanding the roles and functions of existing transportation management systems, utilizing an existing agency to lead the development of a multimodal ITMS, establishing agency partnerships with shared funding and management responsibilities, and creating a new organization charged with the same responsibility. In addition, a multimodal ITMS could be organized in a variety of ways. For example, all of the modes and responsible agencies could be located in the same building or control center. Under another possible organizational scenario, they may be physically located in different areas, but may share information and communicate through a variety of advanced technologies.

Regardless of the exact organizational structure used, there seem to be at least three basic levels that are appropriate for consideration in the development of a multimodal ITMS. These levels relate to the sharing of information, facilities and equipment, and control. Each of these represents a step toward greater integration, with the last level representing a truly multimodal ITMS.

The first level focuses on the sharing of information and data among the various modes and organizations involved in a multimodal ITMS. In this situation, the decision on how to react to the real-time traffic information and the specific actions which might be initiated in response to an incident would be left up to the individual entities. At the second level, the different organizations would share information, as well as facilities and equipment. This represents a step along the continuum toward greater integration.

Finally, at the last level, the various organizations would share not only information and facilities, but also control. In this scenario, specific actions could be initiated by different agencies in response to pre-agreed upon plans and decision support systems. Thus, control over different elements of the transportation system would be shared among the agencies. Accomplishing this sharing of control will not be an easy process, however, as it will require some agencies to share their historic responsibilities. The institutional issues discussed previously will need to be addressed to accomplish this last step.

This paper has examined the modes and functions to be incorporated into multimodal ITMS. It has provided a discussion of the multimodal ITMS concept and the various components to be included in such a system. Potential technical and institutional issues that might be encountered in the development and operation of a multimodal ITMS were described, and alternative implementation strategies were presented.

A number of areas will need to be examined in more detail to help advance the development and operation of multimodal ITMS. Additional research examining the technical and institutional issues identified in this paper would be beneficial in fostering the deployment of ITMS. For example, further research is needed on the development of a common system architecture, as well as examining the issues associated with the design and functional integration of a specific ITMS. Designing the decision support systems, communication protocols, and control strategies, represent other areas where further research is needed.

A number of institutional issues should also be examined in more detail. Identifying approaches to overcome potential liability and other legal concerns will be critical, as will developing innovative partnerships among public and private sector groups. The successful deployment of a multimodal ITMS will require changes in the traditional roles and responsibilities of public agencies and private operators. Change is never an easy process, and identifying approaches to help overcome potential concerns would be valuable.

Although not examined in this paper, public acceptance will be an important factor in the ultimate success of multimodal ITMS. Additional research on public attitudes toward advanced technologies, real-time information, incident diversion strategies, and privacy would be beneficial in the design of ITMS. Examining the human factors issues associated with the operation and use of the different components of a multimodal ITMS would also be of benefit.

As discussed in this paper, the design, development, and operation of a multimodal ITMS will not be an easy process. Numerous opportunities exist, however, and possible technical and institutional issues can be addressed. The potential benefits of a multimodal ITMS are well worth the time and effort spent resolving these concerns, however. Incorporating all of the modes and functions discussed in this paper into a multimodal ITMS will assist in ensuring the continued vitality and economic health of metropolitan areas throughout the country.