Incident Management > Incident Clearance                  Printer-friendly version

• Introduction 
• Incident Clearance Plans, Methods and Technologies
• Incident Response Plans
• Policies and Legislation
• Accident Investigation Sites
• Emergency Vehicle Access
• Incident Detection and Verification
• Incident Response
• Incident Clearance
• Incident Clearance Programs and Performance
• Freeway Service Patrols
• Program Evaluations 
• Summary of Evaluation Findings 
• Assessment of Evaluation Methodologies 
• General Guidelines 
• Conclusion
• References

The main objective of an incident clearance program is to keep the roadway free of any temporary obstructions. Efficient incident clearance requires coordination between several parties, both off and at the scene of an incident: police, medical personnel, firefighters, and highway patrols, among others. In fact, incident clearance programs have been established partly due to poor response when major accidents have occurred. 

Incident clearance is a multidisciplinary process and consists of several different methods. In several instances, incident management and thus clearance efforts are coordinated from a Transportation Management Center (TMC), a traffic operations center that receives and processes traffic information and data from several sources. The TMCs receive incident detection notifications, verify them, and coordinate response and clearance efforts between police, service patrols, tow trucks, and other emergency response teams.

INCIDENT CLEARANCE PLANS, METHODS AND TECHNOLOGIES

Incident Response Plans

 An incident response plan basically consists of pre-planning and post-planning. Preplanning improves communication, coordination and cooperation among all response  agencies. Through preplanning, agencies try to define roles and responsibilities and to develop policies and procedures that speed incident clearance times. Planning  detour routes that allow traffic to be routed away from the incident quickly is also given prominence. The planners critique past incidents to determine the best way to handle similar situations in the future. 

The post-planning addresses the actual clearance process. This is where the service patrol and the different emergency services come into play.

The TMC is usually responsible for gathering information and  managing the response to the incident.  The severity of the incident determines the level of response and the agencies to be contacted. Good communication links with such response agencies and emergency services are needed. 

For example, NAVIGATOR, Georgia's intelligent transportation system, gathers information from a variety of sources, processes the information using Geographic Information Systems software, then formulates an appropriate response plan. The response plan is reviewed before being implemented by NAVIGATOR and communicated to the public. This allows the public to make informed choices about their transportation options. 

Policies and Legislation

Quick clearance policy: 

Abandoned Vehicle Policy: 

A study conducted by Utah Service Patrol  revealed that there were 267 accidents involving vehicles parked in the emergency lane of freeways in Utah (1982). According to the abandoned vehicle policy adopted by the UHP, abandoned vehicles left parked on the paved portion of any freeway or major highway are towed within two hours. Within the I95 Coalition agencies(which consists of Maryland State Highway Administration, New York City Department of Transportation, etc.), a range of time limits exist before abandoned vehicles are removed/towed. The policies range from as short as one-half hour to as great as 72 hours. The typical time limit appears to be 24 hours.

'Hold Harmless' Policy

The hold harmless policy is intended to permit involved agencies to more rapidly open the highway or facility to normal conditions by removing certain vehicles from the facility on an urgent basis utilizing available resources, recognizing that public safety is of the utmost importance. If additional damage to the vehicle results, the liability for the damage may be the responsibility of the owner or the highway/facility agency, depending on the policy approved. 

Multi-agency Cooperation

The clearance and site management process is a multi-agency process. The training for these must include all agencies involved in incident management to build a cross agency team working together to accomplish individual agency goals. Through inter-judicial training the personnel gain a better understanding of each other's  concerns, missions and facilitate communications, thereby improving clearance times.

Joint training among incident response agencies is critical to improving response times. A standard set of interagency plans, tailored for various incident detection scenarios and supported by shared data improves the speed of the incident response process. Optimum response depends on accurate and rapid verification, as well as coordinated agency planning and communication.

Accident Investigation Sites (AIS) 

Emergency Vehicle Access:

Improved access to major incident sites can be obtained by providing freeway access ramps and by allowing emergency vehicles to travel on HOV lanes and freeway shoulders.

 INCIDENT DETECTION AND VERIFICATION

The next step that follows in the incident management program is the determination of the precise location and nature of the incident, termed as Incident Verification. In some cases incident detection and verification occur together. Detailed information collected during incident verification enable the dispatch of the most appropriate personnel and resources to the scene and avoids deploying resources to false incident reports. Verification methods include in-person verification by dispatched personnel, synthesis of multiple cellular phone calls, and the use of CCTV cameras.  Providing toll-free cellular phone numbers to report incidents, strategic placement of CCTV cameras at high-incident locations, etc can improve detection and verification times.

INCIDENT RESPONSE

• Service Patrol Fleets
• Towing and Recovery Vehicles
• Law Enforcement  Fleets
• Fire Engines/Rescue Units/Ambulances/HAZMAT Response Units
• Changeable Message Signs (CMS) / Arterial Signal Control

The management of resources to remove the incident and reduce the impact on traffic flow involving coordination of activities by various responding agency personnel is termed as Site Management. Site Management provides for safety and security at the incident scene. and is usually under an Incident Command System (ICS). The ICS consists of a hierarchy of predefined roles and responsibilities for incident management command, operations, and communications. The ICS approach is followed nationwide for incident clearance.

Towing services represent a key component in the incident response plan. These services conduct the vehicle removal and/or towing services for the incidents. Their quick response to the incident (upon notification) and their efficient conduct of the towing/removal activity can be a key step in minimizing the incident clearance time and the opening up of a highway facility or a portion of the facility to the motoring public. As such, they represent a vital activity in the incident management plan.

Agency owned tow trucks or service patrols are the actual response teams that assist stranded motorists, or police personnel when required. Their tasks may include cleaning spilled loads or debris, towing disabled vehicles to the freeway shoulders or off the freeway, assisting drivers with minor mechanical problems, administering first-aid, and controlling small vehicle fires. 

Where an incident is suspected of or involves a "hazardous material", the lead authority for handling the incident rests with the HazMat Team. The Lead Officer, in this case, is typically the Fire Chief or Lead Fire Department Officer. The duty of this Officer is to direct the handling and clean up of the "hazardous material". The Officer has the primary responsibility for the conduct and direction of the incident management. In areas where questions or conflicts may arise, this Officer serves as the decision maker. In many cases, this Officer will work with the Police agency (individual who would typically have responsibility for the incident) to more effectively handle the incident. 

Computer Aided Dispatch (CAD) of response vehicles helps maintain optimum response times. Dispatching strategy is also important. A fundamental question that arises while dispatching incident response crews is whether to send a closer vehicle or wait for another vehicle which is even closer, to become available. The latter leads to reduced service time, adding to capacity and providing stability at higher levels of utilization. But the waiting for a vehicle to become available adds to uncertainty, contributing to expected traffic delay. Hence any good dispatching policy must provide for a hybridization of the two objectives, trading off greater certainty in response time against stability at higher utilization levels. A recent work  by UC Berkeley(UCB-ITS-PWP-2000-14) has attempted to answer these questions through analysis of idealized highways. 

INCIDENT CLEARANCE

Incident Clearance Programs and Performance

Wisconsin DOT's freeway traffic management system known as MONITOR  provides information to WSDOT's public web site and to media and local agencies to inform them of incidents on the freeway. Other than the system components such as ramp meters, cameras, safety patrols, etc., the officials credit the success of the program to the fact that the stakeholders in the Wisconsin public safety and transportation departments understand the importance of incident management and communication. Ongoing training, education and briefings (after major incidents) keep them abreast of continuing issues and possible solutions.

Many of the existing incident management systems such as the Highway Helper Program in Minneapolis, the Incident Management component of the CHART Program in Maryland, and the Emergency Traffic Patrol in Illinois incorporate technologies such as cellular call-in, loop detectors, video monitoring, etc. A summary of incident management benefits published by ITS DOT (www.its.dot.gov) show a reduction in clearance time of 8 minutes for stalls and 5-7 minutes in tow truck response time.

Another useful aid which has been successfully used  for clearance is video monitoring. In Richardson, Texas, the information provided by the camera is used by tow truck dispatchers to position appropriate vehicles near the collision site prior to the request for service from the police department. This advance notice reduces the incident response time for clearance by 5-7 minutes on average. Yet another useful aid  in the clearance process is total station surveying equipment, which can be used for traffic accident site mapping services. Electronic total station surveying equipment can be used to produce professional computer generated scale plans of accident scenes and thus help in the clearance process.
A performance evaluation of some of the incident management programs is given below.

Table 1 Incident Clearance Programs - Measures of performance

Program	Reduction in Incidents	Reduction in response time	Benefits or B/C ratio
TransGuide, San Antonio	Total accidents reduced by 35% secondary accidents - 30%; Overall accident rate reduced - 41%	Response time reduction - 20% Delay savings/incident 700 vehicle-hours Reduction in fuel consumption/incident 2600 gallons	Annual Savings $1.65 Million
TIMS, Philadelphia	Incidents reduced by 40%	Freeway closure time reduced by 55% Incident severity rate reduced by 8%
GDOT NaviGator System, Atlanta	NA	Mean time between incident verification and clearance of lanes reduced from 40.5 min to 24.9 min.( The max. time reduced from 6.25 hours to 1.5 hours)	Cost savings of $44.6 Miliion/year 2.3
Maryland CHART program	NA	Benefits amount to 2 million vehicle-hours of non-recurrent congestion delay savings per year.	5.6

All benefits and costs estimated for a one-year period
N.A: information not available

Freeway Service Patrols

The most visible components of an incident clearance program are the service patrols. These operate in most major metropolitan areas of the United States (see the tables below). These programs usually consist of a fleet of light-duty trucks, equipped with two-way radio communication to a traffic control center. Often times the local transportation authorities will contract with private tow truck companies to provide incident clearance services, instead of operating a fleet of vehicles themselves. 

Patrols usually operate on "beats" along a pre-defined stretch of highway, although sometimes they are dispatched on demand. The hours of operation vary with locality and with the specific purpose of the clearance effort: most operate only during peak hours on weekdays only, while a few work around the clock every day of the year. Trucks carry emergency and traffic control signs, gasoline and other materials and tools to assist disabled cars, and first aid kits. Usually these trucks are equipped with tows or push bumpers, which allow them to move vehicles off the road. 

FSP programs vary in size from two vehicle operations to programs with as many as 150 tow trucks, as is the case in the Los Angeles Metropolitan Area. Correspondingly, coverage varies from just a single bridge or tunnel, to several beats within a large metropolitan area. Tables 2 and 3 list incident clearance programs in the United States and Canada, including characteristics such as number of vehicles, hours of operation, and funding sources: 

• Table 2: Urban Regions and Corridors 
• Table 3: Spot Locations (Tunnels and Bridges) 

Program Evaluations:

The quantifiable benefits from incident clearance efforts are realized at the system, and not at the individual level. Average travel delay savings, per vehicle or per person, are usually small, since most incidents last for only a few minutes, and most people are caught in incident-related congestion only occasionally. Yet it is the "unmeasurable" benefits of freeway service patrols that the public appreciates: a sense of security that stems from knowing that someone will be there to help, plus the confidence that, when an incident occurs, it will be dealt with expeditiously. Public support is most clearly reflected in the fact that voters have supported sales or vehicle registration taxes dedicated to fund incident clearance programs.

Summary of Evaluation Findings:

Besides benefit/cost ratios, other measures of performance have been used to evaluate incident clearance programs. Most systems are credited with reducing incident response and clearance times, in amounts that vary depending on the extent of assistance both before and after patrol operation began. Estimates of traffic delay reductions depend on prevailing traffic conditions (traffic volume, incident topology, and roadway characteristics) in the corridor or region where services are provided, and so are difficult to generalize across programs. In some cases a reduction in the occurrence of secondary accidents has been observed; this is attributed to reduced incident duration and to better coordination among parties at the incident scene. 

Assessment of Evaluation Methodologies:

While it is unrealistic to collect all the above data system-wide, program evaluations could be designed to take advantage of existing freeway instrumentation, for example by focusing on specific road sections. More importantly, an evaluation should be designed in advance of implementing clearance efforts, thus providing opportunities to collect before and after data. Even then, it should be kept in mind that measurement of traffic delays is often expensive and time-consuming, if at all possible. Analytical methods will be necessary, but they are hardly a substitute for good quality empirical data. In particular, traffic simulation programs should be used carefully when estimating traffic delays, since they may not adequately model the effects of incidents on the traffic stream. 

In estimating benefits, care should be taken not to double-count the value of services rendered. Two issues should be taken into account: the first is that in some instances these services could have been provided by a private tow truck operator, in which case the value of the service is not a net benefit. The second issue is that, although these services are usually provided free of charge, all motorists may indirectly bear the cost of such services. Whether this occurs depends on the specific funding mechanism employed. 

General Guidelines

It is generally recommended to start with a small team, with a secured and dedicated source of funding. It is also a good idea to publicize the existence of the freeway patrol, so that the public can take advantage of its services. In places where freeway call boxes are not readily available, the provision of a dedicated cellular phone number may significantly reduce incident detection times. 

In places where freeway service patrols operate, they are usually the first to detect most incidents. But as mobile cellular phones become ubiquitous, it may prove more efficient to keep the patrol vehicles on- call, instead of on the road. The cost of having several vehicles on the road should be traded-off against the benefits of lower response times, assuming comparable detection rates. One strategy is to optimally locate vehicles on the freeway network using the spatial and temporal distribution of incidents (see Wilmink and Immers, 1996). In addition, instead of defining a service area per patrol vehicle, tow trucks can be allocated to an incident on the basis of expected shortest travel time to the incident site. 

When organizing incident clearance programs, institutional arrangements that do not require maintaining an in-house vehicle fleet should be examined. In several metropolitan areas private tow trucks already provide some level of motorist assistance. Large scale programs could have serious problems with these private operators, if it is perceived that public agencies are taking over a significant portion of their business. One solution that has already been implemented is to contract with these companies for the provision of incident clearance services. 

Such public/private partnerships add another layer of complexity to an activity that already requires a large degree of cooperation among several public agencies. The need to clearly lay out each agency's responsibilities cannot be over-emphasized. This includes, but is not limited to, establishing a clear chain of command at the scene of an accident, especially when injured people or hazardous materials are involved. In addition, agencies need to deal with the liability issues that may arise when private property is damaged while being removed from the road. The states of California, Texas, and Illinois have passed legislation that ensures the right to remove cargo or vehicles that are blocking a roadway or that are deemed a public hazard, without consent of the owner or liability for damages incurred in the process, as long as the removal is not carried out recklessly or in a grossly negligent manner (ITE 1996).

Evaluation results of some of the service patrol programs is given below.

Table 4
Benefit-Cost Evaluation of Incident Clearance Programs

Program	Benefits	Costs	B/C
Motorist Assistance Patrol Charlotte, North Carolina	Reductions in incident-related delay were estimated using a traffic simulation program (estimates not available).	The initial start-up cost for this program was $2,850,000 (1992 US$).	7.6
Emergency Traffic Patrol Chicago, Illinois	N.A.	Annual program costs (based on 1990-1993 data) were $3.5 million in operating costs, and $5.5 million in overhead costs.	17
Freeway Service Patrol Los Angeles, California	A B/C evaluation of the Los Angeles FSP is currently (Nov. 97) underway. The evaluation focuses on a 7.8 mile segment of I-10, the San Bernardino Freeway, between Eastern Ave. and Santa Anita Ave. This beat has a traffic of 249,000 veh/day. Travel time, incident, traffic flow, and speed data were gathered over a 30 day period, with the FSP in operation. These data were used to calculate delays for assisted and unassisted incidents ("after" study). Queuing models and L.A. CAD data were used to estimate the delays that would have ensued had the FSP not been in operation ("before" study). Results are not yet available.	Average operating cost: $39.2 per truck-hour, or approximately $3,530 for a 30 day period, using 3 trucks and given 8 hours of operation per day	N.A.
Freeway Service Patrol San Francisco Bay Area, California	The FSP evaluation focused on a 9 mile section of I-880, located in Hayward, Alameda County. Benefits were quantified primarily in terms of savings in travel delay. Other measures of effectiveness include savings in fuel consumption and air pollutant emissions. To compute incident delays, travel times for vehicles affected by an incident were estimated from loop detector data, and compared to incident-free travel times. Fuel consumption was estimated from average speeds during the duration of the incident, and air pollutant emissions were calculated using California Air Resources Board emission factors. Delay savings per breakdown: 42 veh-hrs Delay savings per accident: 20 veh-hrs Avg. fuel consumption savings: 31 gal. per breakdown Avg. emission savings: 3.5 kg. of HC(32 kg/day), 35.8 kg. of CO (322kg/day)and 8.9 kg. of NOx (798kg/day)per breakdowns. The following factors were assumed: a value of $10 per hour of delay, and a cost of $1.15 per gallon of fuel.	The annual cost of the FSP operation at the test site was estimated at $295,500, for a total of 257 service days, or 4,084 truck-hours. This figure includes total capital, operating, and administrative costs. The FSP program started on August 1992 and as of January 1997, it had assisted more than 90,000 drivers.	3.3
Courtesy Patrol Program Denver, Colorado	It is estimated that the program resulted in reduced traffic delays valued at $0.8-$1.0 million for the morning period, and $0.9 to 0.95 million for the evening period. This assumes a value of time of $10 per hour. Estimated traffic delays were obtained by modeling the effects of incidents with a deterministic queuing model.	Program costs varied with each tow truck operator and beat, between $29 per hour and $38 per truck-hour.	10.5 to 16.9
Motorist Assistance Program Houston, Texas	Benefits to assisted motorists, measured as the value of services rendered were estimated at $125,000. This is based on the actual number of services provided, and costs estimated by the Houston Wrecker Association. Benefits to other motorists, measured as savings in travel delay were estimated at $3,600,000. Travel delays with and without MAP were estimated using a traffic simulation program, calibrated with site-specific data. The proportion of roadway capacity reduced due to different types of incidents was also estimated from field measurements. A value of time of $10.47 (1992 prices) was assumed.	The total cost to operate the two vans was approximately $196,500, itemized as follows: $17,075 annualized vehicle purchase, maintenance and equipment costs (assuming a three-year depreciation period); $146,000 for direct labor costs (patrol deputies and part-time clerk); and $16,300 administrative costs (management personnel, office lease, etc).	19
Motorist Assistance Program Houston, Texas	Benefits were measured as the value of traffic delay reductions that could be attributed to the Motorist Assistance Program. Traffic delays were estimated to be 2.2 million veh-hrs per year. Various estimates of potential traffic delays without the program were obtained by increasing observed incident duration by 5, 10, 15 or 20 min. Using a value of time of $9.76 per person-hr resulted in a net value of time savings between $0.6 million to $3.1 million.	Funding for the 1990-1991 period totaled approximately $1.3 million. Total operating costs were $1.1 million, 86% of which corresponded to salaries, and the rest to equipment and maintenance. In addition, program costs included a $198,000 expense for program evaluation.	7 to 36
Freeway Service Patrol Los Angeles, California	N.A.	Estimated annual (1992) costs were $9 million. About $8 million are direct contractor operating charges. Operating costs varied between $24 and $70 per truck-hour, depending on beat and contractor. Other costs included supervisors and traffic dispatchers payroll, communications equipment and radio frequency leases, program evaluation, and other miscellaneous supplies	12 to 15
Highway Helper Minneapolis-Saint Paul, Minnesota	Program benefits were estimated as the value of reduced delay due to assistance to stalled vehicles during peak hours only. It was estimated that the duration of a stall was reduced by 8 minutes when assisted by a highway helper, and that each minute of incident duration caused 5 vehicle-hours of delay. Given 1,067 assists provided per month (84% stalls), 64% during peak periods, this resulted in approximately 275,000 hours of delay. Assuming a value of time of $5 per hour, benefits totaled $1.4 Million per year.	Total annual program costs were $600,000 (2000) distributed among salaries and overtime (69%), supervision (14%), equipment (5%), maintenance and operating costs (9%), and others. Annual benefit through reduced delay totals $1.4 million.	2.3
Emergency Patrols Ontario, Canada	Reductions in delay and fuel consumption. (Estimates not available).	Maintenance and operating costs amounted to approximately $1.4 million per year (1993 canadian dollars)	2 to 30
Pittsburgh, Pennsylvania	Reduction in traffic delays (estimates not available)	Annual program operating and maintenance costs were approximately $4 million (1993).	N.A.
Incident Response Teams Washington State	N.A.	The cost of an equipped incident response truck was estimated to be $50,000 per year (estimated useful life is eight years). Annual labor costs were approximately $40,000 per driver, and other nominal costs were estimated at $100,000 for the statewide program.	N.A.
Courtesy Bridge Patrol Tampa, Florida	N.A.	The contract price for the bridge patrol in 1991 was $141,400 for a period of twelve months. Given the number of assists, this results in an average cost of $433 per incident cleared.	N.A.

All benefits and costs estimated for a one-year period
N.A: information not available

Summary Table 5

	Other Measures of Performance
Program	Performance Evaluation
Motorist Assistance Patrol Charlotte, North Carolina	Cooperation between agencies involved in attending incidents has resulted in reductions in the time to detect, react to, and clear incidents. The most important problem faced by the program was securing capital and operating funds.
Emergency Traffic Patrol Chicago, Illinois	The traffic patrols assist in more than 100,000 incidents per year. An 18% reduction in secondary accidents and 60% reduction in congestion were attributed to their operation.
Courtesy Patrol Program Denver, Colorado	Average delay savings for the morning and evening commutes were estimated at 98 veh-hrs per incident and 75 veh-hrs per incident, respectively. The estimation method was based on a deterministic queuing model.
Freeway Service Patrol Hayward, California	Direct benefits to assisted motorists resulted from faster response time, and from the value of services rendered. Average response time savings were estimated at 16.5 minutes per assisted breakdown, and 12.6 minutes per assisted accident. All services provided free of charge to motorists; the cost to a tow truck ranges from $5 for refueling to $60 for towing off the freeway.
Motorist Assistance Patrol Houston, Texas	Average incident duration was estimated to be reduced by approximately 15 minutes. Total number of assists were 893 in the morning period and 1,962 in the evening periods (service was provided in both directions during evenings, but only in the rush hour direction in the mornings).
Motorist Assistance Patrol Houston, Texas	The patrols assisted in more than 24,000 incidents (32,700 persons) during the 1990-1991 period.
Freeway Service Patrol Los Angeles, California	Average response time per incident was reduced from over 20 min. to about 7 min. In 1991, approximately 280,000 motorist were serviced; in 1992 it was estimated that each patrol provided an average of nine assists per day. The FSP program resulted in the direct creation of 100 new tow vehicle operator jobs, and it was estimated that 37 indirect new jobs were added to the region's economy.
Highway Helper Minneapolis-Saint Paul, Minnesota	Between March 1993 and February 1994 12,800 incidents were attended, and 15,870 services were provided (some incidents required more than one service). A total of 533 vehicles were removed from freeway lanes or ramps.
Emergency Patrol Ontario, Canada	The Emergency Patrols have contributed in reducing traffic delays, secondary accidents, and fuel consumption.
Incident Response Teams Washington State	Benefits resulting from this program include shorter incident response times, shorter lane and roadway closure times and fewer total roadway closures. Average freeway incident clearance time (for large trucks) was reduced to 1.5 hours, compared to 5 to 7 hours without the incident response team. In addition, it is believed the program has helped develop better working relationships among all involved agencies, and contributed to a better understand of other agencies' responsibilities at an incident site.
Service Patrol Demonstration Program Seattle and Tacoma, Washington	Quantifiable benefits include: 15 minute reduction in average accident duration, and 6 minute reduction in average disabled vehicle incident duration. Other benefits observed were a reduction in debris-related incident duration, a reduction in the time to clear incidents that require a tow, and a reduction in police average response time, from 15 to 10 minutes.
Courtesy Bridge Patrol Tampa, Florida	Clearance team efforts have resulted in a reduction of 3.6 secondary accidents per year.

CONCLUSION

Though incident management techniques are now being used widely, mainly in metropolitan cities, incident management has not reached it full potential due to institutional barriers. Coordination between the different agencies involved in the management and clearance process is cardinal to the success of any program. Furthermore, building a "mandate" for incident management programs is a key step in making progress. The primary objective must be to overcome the general public's lack of awareness of what incident management is and what it can do to help alleviate traffic congestion. 

REFERENCES

• Kaan Ozbay and Pushkin Kachroo, Incident Management in Intelligent Transportation Systems, 1999
• Incident Management Successful Practices - A Cross-Cutting Study, Improving Mobility and Saving Lives, April 2000
• Chung Edward and Rosalion Natalia, Effective Incident detection and Management on Freeways, Research Report, February 1999.
• Booz-Allen & Hamilton, Incident Management: Detection, Verification, and Traffic Management, September 1998 
• ITS Joint Program web site- Incident Management Programs http://www.its.dot.gov/tcomm/itibeedoc/imp.htm 
• "Incident Management: Detection, Response and Operations" (I95 Coalition-Report)  http://www.i95coalition.org/PDF/Reports/project2/2-94-03.pdf
• The Utah Highway Patrol home page - New Policy, New Laws
• www.uhp.state.ut.us/history/Chapter4/NewPolicyNewLaw.html 
• Georgia NAVIGATOR home page  
• Maryland Chart Program
• Trans Guide web site 
• Moving ahead in time, Article from ITS World, September/ October 2000
• ITS Benefits Database http://www.mitretek.org/its/benecost.nsf/BenefitsHome?OpenFrameSet
• http://www.azfms.com/DocReviews/Jan98/art14.html

Author: Indu Sreedevi and Rosella Picado. Last Update: 05/01/01