The Illinois State Toll Highway Authority has developed and maintained a strong operations focus for several decades.
This integrated operations approach centers around cooperation among numerous internal and external groups. These include the Illinois State Police, local emergency responders, recovery companies and internal Tollway departments such as legal, communications, engineering, maintenance and toll services.
A primary focus of the integrated operations approach is incident management. The National Traffic Incident Management Coalition (NTIMC) estimates that approximately 25% of delay is caused by nonrecurring congestion from incidents, crashes and other traffic-related events. Recognizing this, over the last two decades the Tollway has established an aggressive and comprehensive incident-management program that strives to provide the highest level of safety for all affected by crashes and other incidents on the Tollway’s interstate highway system. The Tollway’s incident-management program follows the guidelines established by the National Incident Management System. In addition, the Tollway is actively involved in the development of a national policy on incident management as part of the NTIMC.
The Illinois Tollway has established formal agreements with all emergency services (fire, recovery, EMS, etc.) that respond to incidents on the Tollway system. These agreements formally emphasize the importance of on-scene cooperation, communication and coordination among all incident responders. The Tollway is unique in this regard and has jointly worked with the Illinois Fire Chiefs Association to develop incident-response training. This includes working directly with training officers from individual fire departments and fire-protection districts to specifically tailor training for fire department shift personnel who respond to Tollway incidents.
The Tollway has Maintenance & Traffic Division personnel on duty 24/7 to respond to incidents anywhere on the 286-mile system throughout northern Illinois.
The Tollway has Maintenance & Traffic Division personnel on duty 24/7 to respond to incidents anywhere on the 286-mile system throughout northern Illinois. In addition, all maintenance personnel go through initial, as well as annual, incident-response training. The Tollway also operates formal service patrols under several different programs, including Highway Emergency Lane Patrol (H.E.L.P.), Motorist Aid Patrol, Zero Weather Road Patrol and Construction Work Zone Patrol, that assist motorists, help with traffic control and respond directly to incidents on the system. In addition, maintenance personnel assigned to routine activities are empowered to respond directly to incidents that occur on the Tollway system when notified by the Tollway’s central dispatch center. Tollway maintenance trucks are equipped with arrow boards and, in many cases, message boards. The primary responsibilities of Tollway personnel responding to incidents are as follows:
- Determine if there are injuries and notify central dispatch, which, in turn, dispatches the appropriate emergency-services provider;
- Secure the scene. Provide a safe zone for emergency-vehicle placement at the crash scene, closing lanes as dictated by the incident;
- Provide traffic control while emergency services are being provided;
- Coordinate towing and/or recovery efforts if required; and
- Restore traffic lanes to service.
In those instances where the fire department arrives first on the scene, Tollway maintenance personnel immediately establish a safe traffic-control zone that incorporates the presence of emergency-response units already on the scene. Provided with a safe working environment, emergency responders are free to focus on medical assistance, fire suppression, towing, recovery and accident investigation/crash documentation without delay while Tollway maintenance crews manage the traffic control and handle any resulting cleanup prior to the restoration of the travel lanes.
Deep in the data
In the 1990s, the Illinois Tollway invested in its third-generation computer-aided dispatch (CAD) system and shifted to a Windows-based platform to improve reporting capabilities. The CAD system allows telecommunicators in the central dispatch center to monitor system operations, to better track assets, identify resources and respond more quickly to incidents. The central dispatch center is responsible for dispatching both the Illinois State Police District 15 and Tollway maintenance personnel. The central dispatch center also communicates with 56 fire departments as needed and dispatches towing and/or recovery services.
In addition to concern for the safety of incident responders and motorists involved in crashes, the Tollway seeks to minimize the occurrence of secondary and tertiary crashes, which statistically are more severe than the original crash.
In 2002, the Tollway opened its first Traffic Operations Center that houses the Traffic and Incident Management System (TIMS). TIMS combines real-time traffic data collected from roadway microwave sensors supplied under an Intelligent Transportation Infrastructure Program agreement with the Federal Highway Administration (FHWA). Information from approximately 400 traffic cameras on the Tollway system and communications from other regional traffic-management centers are used with this sensor data to provide Tollway staff with a more detailed understanding of each incident, such as how it is unfolding and how it can be best managed. TIMS has the ability to communicate to customers through dynamic message signs (DMS), portable changeable message signs and media and Internet connections.
In order to further improve the Tollway’s incident-response capabilities, in 2003 the Tollway integrated incident information from the CAD system into TIMS—a first for the nation. Operators for both TIMS and the central dispatch center can initiate incident responses, view the same incident data and modify that data in real-time. For example, TIMS operators are able to initiate response for incidents that they observe and direct central dispatch operators to immediately initiate the dispatch of units. Both can update information on the incident as the event unfolds.
Additionally, while in the majority of cases either Illinois State Police District 15 or Tollway maintenance personnel are first to arrive on the scene of an incident, increasingly cameras from TIMS are either the first to observe an incident or are used to visually verify incidents while resources are still en route. This ability greatly aids responders by providing critical information before they arrive on the scene.
The Illinois Tollway places a high premium on the efficient handling of lane-blockage incidents through systems designed to detect and confirm incidents, accurately deploy resources and foster the safe and efficient clearance of lane blockage. In addition to the immediate concern for the safety of incident responders and motorists involved in crashes, this active management helps to minimize the occurrence of secondary and tertiary crashes that statistically are more severe than the original crash that resulted in system disruption and backups. There are several layers to this successful operations management.
Having the proper resources and training continually proves to be critical in proper incident response. The next layer is internal to the Tollway’s maintenance and traffic division. Reports on incidents and Tollway resource responses are internally reviewed weekly. This review is intended to identify short-term trends or operational changes that need to be considered to address immediate issues. Any major incident is critiqued in detail to determine if procedures were followed and if procedures could be improved for future incidents.
The primary sources for data used to generate these reports are TIMS and CAD, although staff input and analysis is always included. Typical measures include average and maximum response times and clearance times for various types of incidents. The Tollway’s traffic engineer, Wilbur Smith Associates, previously determined that response times to incidents decreased 24% after implementation of TIMS. Currently, typical incident-clearance times average 18 minutes for property-damage incidents, while injury crashes average clearance times of 30 minutes. It is important to realize incidents are unique, and response and clearance times can vary considerably. The Tollway tracks these numbers internally to ensure the overall integrated approach continues to work and that average response times generally stay low.
The next layer is internal to the Tollway, but with all of the responsible divisions. As mentioned above, this includes the Illinois State Police, legal, communications and toll services and support contractors such as the Tollway’s general engineering consultant and traffic engineer. This group meets monthly and addresses a wide variety of issues that go well beyond incident management. All major incidents and medium- and long-term trends are discussed in this group setting.
The final layer is with other regional operational agencies. The Tollway meets with state transportation departments, including staff from Illinois, Indiana, Michigan and Wisconsin, to discuss incidents and events that can affect the entire region.
The Illinois Tollway and its traffic engineer continually study traffic patterns and trends across the Tollway system. Wilbur Smith uses real-time traffic data combined with multiple data sources to provide a wide variety of reports illustrating performance standards for the Tollway. With the vast amounts of data produced by both TIMS and CAD systems and demands being placed on the maintenance and traffic division for responses to an ever greater number of questions, TIMS creates an insatiable demand for information. The more reports that are produced, the more data various staff will seek from TIMS and the central dispatch center. The biggest issue is that even though large amounts of data are available, useful, ready information from the data often is not. Consequently, the Tollway and Wilbur Smith set out to determine what could be done with all this data that would be useful for known and anticipated questions.
Several system performance measures have become accepted and used throughout the industry. FHWA nationally tracks measures such as the travel-time index, buffer index, percent congested and vehicle-hours of delay.
The travel-time index is the ratio of average peak period travel times to free-flow travel times. So a value of 0.9 means that section of road will typically take 10% longer to complete the journey during rush hour than during free-flow conditions.
The buffer index represents the average time a user adds to a peak-period trip to expect to get to their destination on time. So, a value of 40% means that for a 60-minute trip, a driver would have to add 24 minutes (leave 24 minutes earlier) to the expected travel time in order to arrive on time.
The percent congested represents the portion of a day a section of road is below free-flow speed.
And the vehicle-hours of delay represents a combination of time and traffic—a heavily traveled section with a delay of a few minutes may have a similar value to a rural section with a long delay.
These performance measures, and many variations of each, are tabulated and reviewed by FHWA, state transportation departments and many other organizations. However, the Tollway is focused on performance measures that more directly address its own incident-management program. Wilbur Smith did a national review and identified more than 100 different incident-management-related performance measures used by various agencies. These measures were reduced to about 25 that were relevant to the Tollway and achievable with the existing or planned data sources. Many were already being tracked by the Tollway (e.g., response and clearance times). Some new measures were easily adapted, such as average distance from a crash to a camera and percent time a DMS is used for incident information.
Adapting and adopting performance measures
However, several of the identified performance measures required a baseline, or benchmark, for comparison. That is, the performance measures might compare traffic conditions during an incident to a hypothetical normal condition of traffic in order to directly determine the impact of that incident. The problem is that there is no accepted definition of “normal.” Is it based on the average speed or the mean speed? Are hourly averages or minute-by-minute averages used? What if that day happens to have light traffic; do you normalize for daily conditions? There remains considerable room for research to help define this condition, but the Illinois Tollway wanted to move ahead and start tracking some performance measures now, rather than wait for the academic community to eventually settle on a definition.
By examining the available data and testing several approaches, the Tollway and Wilbur Smith settled on using seasonal five-minute average speeds for weekdays and weekends. This average represents the baseline for “normal” conditions. After normalizing each day against the average, the Tollway can quickly examine each and every crash and directly measure the impact of that crash against normal. This allows the Tollway to directly measure indexes, such as return-to-normal conditions, and quickly calculate measures such as vehicle-hours of delay per incident. Also, since the Tollway knows how traffic was impacted by a crash, it can directly determine secondary crashes that occur within the impact area.
Toward fewer crashes
Of the measures identified, approximately 10 were quickly implemented. Another half-dozen are being implemented, although some of these are enhanced versions of the first 10. These include environmental measures such as fuel consumption and air quality related to incidents and construction. More direct calculation of vehicle-hours of delay is expected. Also, many of the reports are planned to be integrated into TIMS to work on a real-time basis. For instance, the real-time impact of a lane closure could be monitored to determine if the contractor can work longer that day due to light impact or if the lane closure needs to be removed early.
Since 2008, the Illinois Tollway has experienced an overall reduction in crashes of approximately 40%. While part of this reduction in crash rates was expected as a result of the conversion of mainline toll plazas to open-road tolling (ORT) and the completion of major widening and reconstruction on much of the Tollway system, there also was a significant reduction in crash rates on portions of the Tollway untouched by construction. Roads such as the Jane Addams Memorial Tollway (I-90), where ORT was completed in 2006 and only a small segment of capacity additions have been completed in recent years, saw a decrease in crashes from 2008 to 2010 of more than 20%.
The central dispatch center is responsible for dispatching both the Illinois State Police District 15 and Tollway maintenance personnel. It also communicates with 56 fire departments as needed and dispatches towing and/or recovery services.
A study of national trends concluded that this decrease was attributable to a variety of operations-focused efforts, including aggressive action by the Tollway to manage traffic and incidents. The identified integrated operations include coordinated interagency cooperation, training and widespread deployment of intelligent transportation systems that allow the Tollway to monitor and guide traffic in real-time and convey information on operations to the traveling public. The final result showed one-third of the crash reduction was attributable to these operations programs resulting in approximately 1,300 fewer crashes each year. When the relatively small amount of money invested in operations is compared to the cost of ORT conversions and capacity additions, the benefit-cost ratio for operations investments was 1.2:1 vs. 0.01:1 for ORT conversions and capacity additions. While the capacity additions will have a more favorable benefit-cost ratio when compared to congestion relief, this still demonstrates the value of integrated operations on an annual basis.
Performance measures are helping the Tollway show value for its integrated operations approach to incident management. The Tollway finds itself in a position where the integrated operations began well before the data was available for performance measures. This means that it is impossible to go back and determine incident response times from 20 years ago versus today. Consequently, the Tollway finds itself using the measures to help illustrate the advantages of this approach more so than making large operational changes. One telling value is the percent of incidents with no impact to traffic: approximately 65%. So, approximately two out of three crashes on the Tollway system are handled without noticeably impacting adjacent traffic. This compares very favorably to similar systems around the country that may experience only 25% having minimal impact. This measure alone is a testament to the success of integrated operations for the Tollway. TM&E