4.1.1Display Map

The display map will graphically show the location and status for the field devices (e.g., VMS, CCTV cameras, TARs, shazam signs, traffic signals, vehicle detectors and pavement sensors). The display map will contain icons that indicate the status of the monitored sites/devices. It will also allow system operators to zoom to different levels of detail in the CHART II network. The highest level will be the I-95 Corridor from Maine to Virginia, and will display state boundaries, state names and major roadway shields and names. The first zoom level will show the State of Maryland and adjacent states, and will display all interstates, county lines, and major cities. The next zoom level, the Maryland statewide view, will be the default view.

System operators will observe traffic conditions and perform their duties and major functions from monitoring the data that are shown on the display map. These functions include:

The following sections describe the graphical features of the display map that can be used by system operators to perform their daily responsibilities.

4.1.1.1 Traffic and Roadway Monitoring

Field devices will allow system operators to monitor activity on the roadway system. These devices include

4.1.1.1.1 Vehicle Detectors

System operators rely on vehicle detectors to collect traffic parameters, such as vehicle volume, speed, and occupancy. These parameters help operators determine demand levels, capacity utilization, potential incident and/or bottleneck locations, and level of service or performance of roadway segments. The traffic parameters are important to operators because they aid in describing roadway conditions.

The CHART II system will allow operators to view vehicle detector data on the display map. The location of vehicle detectors will be represented as an icon on the display map from which link data and/or multi-lane link data will be available by clicking on the icon. Data will include vehicle volumes, occupancies, speeds, and travel time based on calculations from information obtained from the existing vehicle detectors. Icons representing lane links on the display map will change color when vehicle volume, occupancy, and speed data reach user defined thresholds.

The display map will indicate operational aspects of the vehicle detector data. The parameter speed will be displayed as colors on map links that are within certain threshold values or as percentage differences between the current speed and the historical speed. This added ability to show information that is different from normal, or to show links that are running better than normal, can be used by system operators and the media when suggesting alternative routes. A small superimposed graph that shows how speed has changed over the last 30 minutes will also be available to system operators. Such a temporal display of this key, dynamic traffic characteristic will assist system operators in making the best possible decisions in carrying out incident management and traveler information dissemination responsibilities.

The CHART II system will allow operators to determine which detectors are associated with certain field processing units (FPU) by clicking on an icon representing the FPU on the display map. This ability will allow system operators to check the status of detectors as needed, and will be a valuable tool for further examining traffic characteristics prior to the system operator making operational related decisions.

4.1.1.1.2 Closed Circuit Television (CCTV)

The use of CCTV provides system operators with the ability to identify and evaluate incidents from a remote location. Use of CCTV cameras allows MDSHA's system operators to:

The CHART II system will provide system operators with the ability to control all of MDSHA's CCTV cameras from their workstations. Operators will be able to click on an icon shown on the display map representing a CCTV camera to view traffic conditions at a particular location. The window showing the live video will be superimposed on the operatorís console. Operators will have the ability to change and pre-set the camera position, focus, pan, tilt, zoom, and make lens adjustments from their workstation. The system will also provide for video switching via the AVCM subsystem that will allow system operators to assign CCTV camera images to a designated monitor for viewing. Operators will be able to route video images to other monitors without relinquishing the video image.

System operators will be able to identify cameras that are in use by other operators by observing the color of the icon. A predetermined color will inform operators that they will only receive a "view-only" video image.

4.1.1.1.3 Signalized Intersections

Providing operators with the ability to monitor traffic signal actuations from their workstations will allow them to easily view and adjust signal timings, change offsets, and manage traffic conditions along arterials. The CHART II system will allow operators to click on an icon representing a traffic signal and perform timing plan changes in response to operational conditions.

4.1.1.2 Information Dissemination

Providing the traveler with advisories, warnings, and rerouting information while they are en-route may reduce congestion and operational problems. Information transmitted may include areas of congestion, incident and construction locations, expected delays, alternate routing, weather advisories, and suggested speeds. Also used by MDSHA to transmit traveler information to en-route motorists in their vehicle are:

4.1.1.2.1 Variable Message Sign (VMS)

Variable message signs provide dynamic information on existing transportation conditions so that travelers can make intelligent route and mode choices. They also provide a certain level of comfort to motorists because they are less likely to become overstressed and accident prone if they know the reason, location, and expected duration of delay. MDSHA uses both fixed VMS and portable VMS to provide dynamic information to motorists regarding a variety of conditions, including:

The CHART II system will provide system operators with the ability to manipulate information displayed on VMS and dedicated portable VMS. System operators will be able to create, modify, schedule (e.g., by day, date, and time), blank, send, and determine the status of messages by clicking on icons representing VMS and portable VMS on the display map. The ability to control messages that are displayed on fixed VMS and portable VMS from an operators workstation will allow operators to better manage traffic conditions.

4.1.1.2.2 Traveler Advisory Radio (TAR)

Traveler Advisory Radio (TAR) provides a relatively economical means of disseminating a significant amount of information about traffic conditions and activities. MDSHA uses TAR to provide more specific traffic information at key locations on an immediate basis than is possible through traditional commercially broadcast traffic reports. The information content of a TAR message can be much greater than a message displayed on a VMS. TAR can utilize live messages, pre-selected tape messages, and synthesized messages based on information in the system database.

The CHART II system will allow operators to view, listen, create, blank, schedule (e.g., by day, date and time), determine the last message sent to a TAR, and send prerecorded synthesized messages from their workstation by clicking on a TAR icon site on the display map. System operators will only have the ability to create new messages if a stored message is not appropriate. Operators will also be able to send stored messages and duplicates of stored messages to multiple TAR sites from their workstation. Additionally, the CHART II system will enable system operators to program a minimum of four TAR stations simultaneously.

4.1.1.2.3 Shazam Signs

Shazam signs indicate the radio frequency at which traffic information is available. Shazam signs usually include flashing beacons that are activated when a message of some predetermined level of importance is being broadcast.

The CHART II system will allow operators to click on an icon representing a shazam sign on the display map and activate or deactivate the flashing beacons. Each shazam sign will be attached to a specific TAR. System operators will be able to activate the appropriate shazam sign after the TAR message is sent, and deactivate the appropriate shazam sign before the TAR message is blanked.

4.1.1.3 Incident Management

Incident management is the coordinated, preplanned, and efficient use of human and mechanical resources to restore roadway systems to full capacity after an incident has occurred. Effective incident management involves quick detection, verification, and response. While the CHART II system will continue to make extensive use of cellular call-in capabilities for incident detection, the CHART II system will enhance MDSHA incident management practices through the implementation of:

4.1.1.3.1 Speed-Based Incident Detection Algorithm

A speed-based incident detection algorithm will be used to identify when vehicles are traveling more slowly than expected and further investigation is needed. Since the occupancy parameter does not provide a direct measure of congestion that relates to the motorist's perception, a speed-based algorithm is recommended as a means for determining if an incident has taken place. Speed is a more readily measurable parameter that can provide a direct relationship with the perception of delay. A speed detection algorithm is also recommended because the existing Whelen radar detector units can collect speed, but not occupancy.

Typical speed based algorithms operate by checking current speed readings for each detector and comparing them with a historical file reading (which has specific speeds for each day of the week under various weather conditions) and the preset threshold. If the current value plus the threshold is less than the historical value, then a counter for a potential incident is set. This procedure will be repeated until the counter reaches a consecutive user preset value that triggers an alarm to the operator.

4.1.1.3.2 Incident Handler Software

System operators currently manage and track incidents using forms that are manually completed. These forms are an important component of the CHART program as they are used by a variety of personnel within MDSHA and the Maryland State Police (MSP) for incident management planning and documentation purposes. These forms often require much time to complete, and can distract system operators from managing incident response activities.

As part of the CHART II system, once an incident alarm is generated based on data obtained from automated sources or non-automated sources and the incident is acknowledged by an operator, the incident handler software will automatically be activated. The incident handler software will automatically select the appropriate CCTV camera within two miles of the incident and enable control at the operator's workstation. If the camera is under control by another user, the operator submitting the report will be notified as to whom has control.

The incident handler software will also allow operators to go through a series of entry boxes/questions that will define parameters for the incident handler software to make suggestions for VMS and TAR messages to be activated. Once basic information on an incident is defined, response screens will be made available listing all applicable devices ordered from nearest to furthest from the incident. Message content will then be suggested for certain devices (e.g., VMS, TAR). The messages suggested will be created according to the provided algorithm and will be updated based on pertinent traffic conditions. The operator will be able to review and hear (for TAR messages) the suggested response message from his/her workstation, and depending upon the operator's system rights, edit the messages. Other devices that were not suggested by the system could also be added into the incident plan at this point by dragging and dropping symbols that represent these devices on the display map. This action will launch the appropriate field equipment subsystem to allow programming the equipment and adding them to the scenario.

Once the operator has completed the series of entry boxes, the incident handler software will distribute submitted incident data to other systems for dissemination. These other systems include internal MDSHA e-mail, paging, and faxing systems; CHART's World Wide Web (WWW) server; the I-95 Corridor Coalition's Information Exchange Network; and the Partners in Motion system. The CHART II system will also interface with VDOT's Traffic Management System (TMS) located in Arlington, Virginia. Incidents located in northern Virginia will be shown with an icon located on the display map, from which CHART system operators will be able to obtain status information by clicking on the icon.

As the incident progresses, operators will be able to update the system with status information by clicking on the icon for the incident and updating the incident report with the appropriate information (e.g., lane closure changes). Operators will also be prompted to update the appropriate field devices based on the status updates.

4.1.1.4 AVL/Mayday

The CHART II system will be capable of tracking Emergency Traffic Patrol and Emergency Response Unit vehicles on the display map once MDSHA has equipped the vehicles with Automatic Vehicle Location (AVL) equipment. The display map will have an icon that represents the vehicles with AVL equipment. The system operator will be able to click on the icon and obtain a wide range of information about the vehicle. The CHART II system will also contain a Mayday feature that allows the vehicle driver to send a message back to the SOC. Operators will be notified at their workstations of incoming IEN alarms through a pop-up dialog window with a flashing indicator, an audio signal, and a change in icon color. A library of pre-programmed messages will be available in an easy scroll-down selection list for forwarding to the SOC. The types of messages that could be sent from the vehicle driver to the SOC include:

Vehicles will also be capable of receiving messages from the SOC. The types of messages that could be sent from the SOC to the driver include:

4.1.1.5 System Failures

The display map for the CHART II system will provide operators with the ability to monitor system failures from their workstations. If any device that aids operators in traffic monitoring, information dissemination, and incident management results in a system failure, the system will notify the operator via the Alarm Ticker scrolling across the bottom of the workstation screen. During normal conditions, the Alarm Ticker can be configured to scroll and illustrate current messages on VMS and TAR to keep the operator aware of the current status. When an alarm condition occurs, the color of the symbol on the Alarm Ticker will change from yellow to red for the purpose of indicating a system failure. System failure alarms will be generated for, but not necessarily limited to the following field devices and their related software, hardware, and communication components: