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Publication Number: FHWA-RD-98-057

Human Factors Design Guidelines for Advanced Traveler Information Systems (ATIS)and Commercial Vehicle Operations (CVO)

 

CHAPTER 9: COMMERCIAL VEHICLE OPERATIONS GUIDELINES

 

This chapter provides human factors design relevant to Commercial Vehicle Operations Functions of ATIS devices. CVO systems cover a broad spectrum of capabilities that have been identified to meet specific operational requirements. The scope of the present review has excluded crash avoidance systems, such as automatic clearance sensing.

The following design topics are included in this chapter:

GENERAL GUIDELINES

CVO–SPECIFIC INFORMATION

 

NUMBER OF CONTROL ACTIONS FOR COMMERCIAL DRIVER ATIS TASKS

Introduction: The number of control actions for commercial driver ATIS tasks refers to the number of control actions, such as button presses, required to complete a specific information retrieval task during ATIS operations while the vehicle is in motion.

Design Guidelines****

Completion of critical individual CVO tasks while the vehicle is in motion should not require more than three control actions, such as button presses.

 

Redesign Tasks to Minimize Required Control Actions

Redesign Tasks to Minimize Required Control Actions

 

Supporting Rationale: In Reference 1, the effects of display modality, level of interaction, and the amount of information on commercial driver performance and system operation were investigated in a simulation study. In the study, a prototype ATIS was used to present routing, vehicle monitoring, and record–keeping information to the driver. Drivers used the system to perform tasks consistent with driving scenarios developed for the study. Tasks requiring greater than three control actions (button presses) were associated with significant increases in task response time and decrements on driver performance. These findings confirmed the general results presented in Reference 2 in which driving performance declined as the number of required manual tasks increased. Reference 1 also found that the number of control actions had a greater effect on driver performance than did the amount of information presented on the display. While display clutter should be minimized, these findings suggest that commercial drivers are skilled at regulating their attention between display monitoring and driving the vehicle.

Special Design Considerations: As described in Reference 1, the design guideline above was derived using fairly simple tasks in which the driver made a series of selections from among several displayed alternatives until a particular task goal was reached. If the time to complete the task is not critical and if (for a particular task) drivers are able to re–direct their attention to the driving scene in–between individual control actions, then a greater number of control actions may not have a negative impact on driver performance or workload. Alternatively, for time–critical operations that require additional visual search of the ATIS display, such as clicking on icons or route segments using a cursor function, even three control actions may be too many for some commercial drivers.

Cross References:

Selection of Control TypeM

Control Movement Compatibility

Control Coding

Key References:

    1. Mollenhauer, M. A., Dingus, T. A., Hankey, J. M., Carney, C., & Neale, V. L. (1996). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Display formats and CVO driver workload. Washington, DC: Federal Highway Administration (FHWA–RD–96–152).

    2. Noy, Y. I. (1989). Intelligent route guidance: Will the new horse be as good as the old? Proceedings of the Vehicle Navigation and Information Systems Conference (pp. 49–55). Warrendale, PA: Society of Automotive Engineers.

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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PRESENTATION OF TRIP SCHEDULING INFORMATION

Introduction: Trip scheduling information refers to information regarding each of the pick–up and delivery points along a predetermined route. This information will aid in the coordination of long, multiple–stop journeys and allow drivers to double–check that the current route will optimize their delivery schedule.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Scheduled pick–up and delivery times

Visual or
Visual and Auditory

Vehicle in PARK

Text description with voice, as needed

 

Schematic Example of Presenting CVO–Specific Trip Scheduling Information

Schematic Example of Presenting CVO-Specific Trip Scheduling Information

Important Note: The map display depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

Supporting Rationale: In Reference 1, a literature review, an analysis, and the results of applying a research–based design tool were used to identify the most appropriate display type, trip status, and display format to use when displaying CVO–specific trip schedule information. It was determined that, due to the amount of information being presented to the driver, it would be necessary to present this information while the vehicle was in park. The complexity of the information also made it advisable to present that information visually so that specific information could be referred to, as necessary. It was also determined that providing the drivers with an overview of the trip on a route map would help them to better see and evaluate their overall schedule.

Special Design Considerations: Trip scheduling information will be important for long–distance commercial drivers, especially those traveling unfamiliar routes. Their main interest is in finding the quickest possible route available for accomplishing their job. Currently, drivers have access to a wide variety of information sources, including dispatchers with complex routing and scheduling systems, other drivers, and well–established routes from years of personal experience. This subfunction will work to incorporate all of these sources, presenting the driver with the optimal route and overlaying the trip schedule for the driver to evaluate.

Because this information will be presented while the vehicle is in PARK, it is not necessary to concentrate on the safety–related issues such as reducing visual and mental workload. Instead, the emphasis should be placed on HCI issues which would help to optimize the display efficiency and ease of use.

Guidelines for trip scheduling information for ATIS reflect certain assumptions regarding the priority, length, and complexity of messages. These assumptions may not apply to all design situations.

Cross References:

Selection of Colors for Coding Visual Displays

Providing Destination Preview Capability

Trip Status Allocation Design Tool

Key References:

    1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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PRESENTATION OF RESTRICTION INFORMATION

Introduction: Restriction information refers to weight, size, and cargo constraints, which might not concern private drivers, but could impact the travel plans of commercial drivers, perhaps even forcing them to choose an alternate route.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Restrictions: Time of day, day of week, size, weight, height, equipment type, cargo

Visual

Vehicle in PARK

Text description or
iconic or graphic representation with text

 

Schematic Example of Presenting CVO–Specific Restriction Information

Schematic Example of Presenting CVO-Specific Restriction Information

Important Note: The map display depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

Supporting Rationale: In Reference 1, a literature review, an analysis, and the results of applying a research–based design tool were used to identify the most appropriate display type, trip status, and display format to use when displaying CVO–specific restriction information. It was determined that this type of information would be most useful to the driver during the predrive trip planning stage, due to the fact that some of the information might cause the driver to change his/her travel plans. Also, due to the complexity and the amount of information being presented, it was determined that the information should be presented visually.

Special Design Considerations: CVO drivers are concerned with things such as: road restrictions for carrying certain cargo, restrictions against using certain road types, and restrictions based on bridge height and vehicle weight. Taking all of these things into consideration can make planning a route very difficult, especially when the intent is to find the fastest route possible. Allowing the driver to view any restriction information automatically, once a route has been entered, should make this job much easier. However, the presentation of roadway restrictions over the entire route may be too much information to give at one time. The drivers should be allowed to break the trip down into succinct chunks associated with waypoints within the total trip. In this way, they will be able to see which parts of the route, if any, need to be replanned, and which parts are acceptable.

Activities performed before the trip has begun are not constrained by many of the safety considerations that are placed on in–transit displays. Therefore, designers can place less emphasis on reducing visual and mental attention, and instead focus their display considerations on standard HCI issues, optimizing display efficiency and ease of use.

Cross References:

Selection of Colors for Coding Visual Displays

Providing Destination Preview Capability

Key References:

    1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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PRESENTATION OF ROUTE SCHEDULING INFORMATION

Introduction: Route scheduling information concerns the coordination of short, multiple–destination routes to minimize travel time or to minimize lateness on deliveries. Therefore, this function would take the driver's destination as input and provide an optimal routing for traveling between destinations.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Optimize delivery schedules

Visual

Vehicle in PARK

Partial route map with or without text

Customer's preferences

Visual

Vehicle in PARK

Partial route map with or without text

 

Schematic Example of Presenting CVO–Specific Route Scheduling Information

Schematic Example of Presenting CVO-Specific Route Scheduling Information

Important Note: The map display depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

Supporting Rationale: In Reference 1, a literature review, an analysis, and the results of applying a research–based design tool were used to identify the most appropriate display type, trip status, and display format to use when displaying CVO–specific route scheduling information. It was determined that this type of information would be presented while the vehicle was still in PARK. Giving the drivers this information would enable them to review a route or area and to determine the relative positions of destinations. The information could also include a global overview of a trip plan. Complex, spatial information such as this would be best presented to the driver visually.

Special Design Considerations: Route scheduling is a CVO–specific function that concerns the coordination of numerous destinations to minimize travel time or to minimize lateness on deliveries. Therefore, this function would take the driver's destinations as input and provide an optimal order for traveling between destinations. The main constraint of a system such as this will be the ability of the user to interact effectively with a computer terminal. This ability depends on computer familiarity and the ability to navigate complex menu structures. This suggests that designers should focus their display considerations on standard HCI issues, optimizing display efficiency and ease of use.

Cross References:

Selection of Colors for Coding Visual Displays

Providing Destination Preview Capability

Key References:

    1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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PRESENTATION OF SERVICE DIRECTORY INFORMATION

Introduction: Service directory information refers to information similar to that found in the yellow pages or a Trucker's Atlas. However, the attraction/services directory has the flexibility of a computer database and would facilitate a wide variety of search methods, allowing CVO drivers to satisfy their current needs in the fewest number of stops.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Directory (index of yellow pages and information from Trucker's Atlas)

Visual

Vehicle at a Stop

Iconic or graphic representation with text
or text description

View currently selected preferences

Visual

Vehicle at a Stop

Iconic or graphic representation with text
or text description

Vehicle restrictions
(e.g., weight, cargo)

Auditory and Visual
or Auditory

Vehicle
in Motion

Alerting tones, chimes, etc., or iconic or graphic representation with tones, chimes

 

Schematic Example of Presenting Service Directory Information

Schematic Example of Presenting Service Directory Information

 

Important Note: The graphic depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

Supporting Rationale: In Reference 1, a literature review, an analysis, and the results of applying a research–based design tool were used to identify the most appropriate display type, trip status, and display format to use when displaying service directory information. It was determined that this information would be best presented while the vehicle was stopped briefly during the normal drive (zero speed). In this situation, drivers are able to devote nearly full attention to the system, but the time available for work with the system is limited by the duration of the traffic control device or any other cause of the zero–speed condition. Therefore, operations during a zero–speed situation must typically take less time than those available during a predrive situation. An estimate of the average stop duration at a red light is about 10 seconds. Therefore, this number is used as a criterion for allocating information to the zero–speed category.

It was also determined that the information should be presented visually, due to the amount of information being displayed on the screen and the number of display interactions necessary for selecting preferences. Any time there are more than 7 to 9 units of information, the information is considered to be complex (Reference 2 and 3). Complex information is displayed more effectively through the visual channel.

Special Design Considerations: A primary factor limiting a driver's use of the system would be the driver's attitudes and knowledge regarding the system. The driver must know how to use the system (although it should be designed to be self–explanatory) and must have confidence that the system can deliver valuable information. Therefore, designers should concentrate more on human–computer interface issues, such as how the drivers will input their preferences and how that information will be displayed.

Implementing this function for commercial vehicles will require a database tailored to the needs of truck drivers. Commercial vehicle operators are interested in finding the services they need as close to one location as possible, so that the number of stops they need to make is minimized. Allowing CVO drivers to select more than one service at a time will help to reduce the number of remaining entries to those that are located within a designated distance from one another. Also, any restrictions that different services/attractions have that would influence a CVO driver should be indicated, including size and weight limitations. Since drivers must specify complicated information concerning their needs, the system will likely include a touchscreen menu system or a remote keypad. Reference 4 examined the visual, safety, and performance aspects of operating a simulated CRT touch panel display while driving at a constant speed along a straight path with respect to lateral lane position maintenance. Looking at and/or operating a CRT touch panel while driving a vehicle along a straight path appears to be a visually demanding, if not dangerous task, as demonstrated by the relatively high probabilities of lane deviations. Therefore, presenting this information during zero speed, as suggested in the above guideline, appears to be the best option.

Cross References: None.

Key References:

    1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).

    2. Labiale, G. (1990). In–car road information: Comparisons of auditory and visual presentation. Proceedings of the Human Factors Society 34th Annual Meeting (pp. 623–627). Santa Monica, CA: Human Factors and Ergonomics Society.

    3. Miller, G. A. (1956). The magical number seven plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63, pp. 81–97.

    4. Zwahlen, H. T., Adams, C. C., & DeBald, D. P. (1987). Safety aspects of CRT touch panel controls in automobiles. Proceedings of the Second International Conference on Vision in Vehicles (pp. 1–10). England: University of Nottingham.

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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PRESENTATION OF DESTINATION COORDINATION INFORMATION

Introduction: Destination coordination information refers to coordinating shipments with customers. This might involve making arrangements for loading and unloading shipments and catering to changes in scheduled pick–up and delivery times.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Information from dispatcher regarding schedule changes and other pick–up/delivery information

Visual

Vehicle
in Motion

Text description or
iconic or graphic representation with text

 

Schematic Example of Presenting CVO–Specific Destination Coordination Information

Schematic Example of Presenting CVO-Specific Destination Coordination Information

Important Note: The map display depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

Supporting Rationale: In Reference 1, a literature review, an analysis, and the results of applying a research–based design tool were used to identify the most appropriate display type, trip status, and display format to use when displaying destination coordination information. It was determined that this type of information would be most useful to the driver if presented while in transit. Displaying messages from dispatch should be done both visually and aurally. This will enable the driver to receive the information without adding to the additional visual attention load, allowing the information to be recalled at a later time if it is forgotten or misunderstood. However, a route map locating the delivery points and the suggested route should be presented visually. Showing a vehicle's position relative to multiple landmarks or routes is considered to be complex information which can be presented most efficiently through the visual channel. According to Reference 2, drivers can process detailed visual information more rapidly than they can process detailed auditory information.

Special Design Considerations: This function allows dispatch to provide the drivers with information relevant to their schedule, including communication with the different delivery points, whenever requested. However, future systems may even have the capability to provide this information directly to the driver. When implementing this function, a dedicated "status line" may be included on some portion of the display.

Cross References:

Selection of Colors for Coding Visual Displays

Providing Destination Preview Capability

Trip Status Allocation Design Tool

Key References:

    1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).

    2. Deatherage, B. H. (1972). Auditory and other sensory forms of information presentation. In H. Van Cott & R. Kinkade (Eds.), Human engineering guide to equipment design (rev. ed.) (pp. 123–160). Washington, DC: U.S. Government Printing Office.

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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COMMUNICATION ACKNOWLEDGMENT FOR CVO IN–VEHICLE SYSTEMS

Introduction: Communication acknowledgment refers to the capability of a CVO in-vehicle communication or messaging system to provide the sender of a message (i.e., a driver or a dispatcher) confirmation that a message was transmitted and received by the system hardware, and to provide information as to whether or not a message has been accessed or "opened" by the recipient.

Acknowledgment is inherent in systems requiring concurrent participation of both sender and receiver in the communication. Telephones and two-way radios are common examples of systems that inherently provide acknowledgment. Acknowledgment is not inherent in systems that allow messages to be sent and received without immediate involvement of both parties (or all parties, in the case of messages broadcast to multiple recipients). Systems that store messages for later access, electronic mail, and telephone answering machines, for example, often do not acknowledge receipt of a message by the hardware, nor access of the message by the recipient.

Design Guidelines*
  • CVO in–vehicle communication systems that do not require direct, real–time interaction between drivers and dispatchers should provide the sender an acknowledgment that a message has been sent and received or, alternatively, a means to determine the status of each message.

  • An acknowledgment should provide the sender feedback regarding the transmission and receipt of messages by the hardware components of the communication system, and also should provide acknowledgment that a message was actually "opened," or otherwise accessed, by the recipient.

  • Communication acknowledgments should be restricted to when the vehicle is stopped or in PARK.

 

Schematic Example of Implementing a Communication Acknowledgment Function for CVO

Schematic Example of Implementing a Communication Acknowledgment Function for CVO

Important Note: The graphic depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

Supporting Rationale: CVO applications require frequent communications between drivers and dispatchers (Reference 1). CVO drivers are responsible for communicating with dispatchers regarding cargo loading and unloading updates, delivery schedules, customer information and updates, and vehicle conditions. Dispatchers receive messages from many fleet vehicles and, in return, send specific instructions and requests for information. The link between these two parties is essential for the productivity of a fleet. Providing a positive indication that a message has been sent and received will eliminate uncertainties that can cause multiple copies of a message to be needlessly transmitted. Eliminating redundant messages frees the communication network for other message traffic.

Special Design Considerations: When a message is opened by the recipient, the system should either automatically send confirmation that the message was received or require the recipient to make a simple input into the system (e.g., a single key press) that transmits confirmation to the sender that the message was read. A positive acknowledgment is required; the absence of an indication is not sufficient to show that the system is operating normally, or that a message has been accessed.

The party sending a message should be advised if a message is purged from the communication system prior to being accessed by the recipient.

Guidelines for the communication acknowledgment information for ATIS reflect certain assumptions regarding the priority, length, and complexity of messages. These assumptions may not apply to all design situations.

Cross References:

The Message Transfer Function

Trip Status Allocation Design Tool

Key References:

    1. Clarke, D. L., McCauley, M. E., Sharkey, T. J., Dingus, T. A., & Lee, J. D. (1996). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Comparable systems analysis. Washington, DC: Federal Highway Administration (FHWA –RD–95–197).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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PRESENTATION OF CVO–SPECIFIC AID REQUEST INFORMATION

Introduction: CVO–specific aid request information refers to the ability to notify emergency personnel (e.g., police, ambulance, towing, fire) of the need for aid. It may also include the ability to provide the driver with feedback regarding the status of emergency services. In the case of commercial vehicles, it may be especially important for emergency personnel to know specific information regarding the type of truck and the cargo it is carrying.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Notify emergency services of hazardous material

Auditory and Visual
or Visual

Vehicle in PARK or Zero Speed

Iconic or graphic representation with text or text description

Inform emergency services of cargo type

Auditory and Visual
or Visual

Vehicle in PARK
or Zero Speed

Iconic or graphic representation with text or text description

 

Schematic Example of Presenting CVO–Specific Aid Request Information

Schematic Example of Presenting CVO-Specific Aid Request Information

Important Note: The graphic depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

Supporting Rationale: Reference 1 used a literature review, an analysis, and the results of applying a research–based design tool to identify the most appropriate display type, trip status, and display format to use when displaying CVO–specific aid request information. An assumption was made that requests for aid would come as the result of either vehicle problems, an accident, or offering roadside assistance. Therefore, this function would operate primarily while the vehicle was in PARK. Using a combination of both visual and auditory display modes might help to ensure that a message would be displayed if the vehicle were in an accident. Even if one of the systems were disabled, there would be a chance that the other system would be able to display the message to the driver.

Special Design Considerations: According to Reference 2, critical messages, such as those from an ambulance dispatcher, should be presented to the driver immediately and should be able to get the driver's attention whether or not the display is actively being searched for information. Communication between the vehicle or the driver and the emergency dispatcher is essential for the effective use of this function. In the case of automatic aid requests, the vehicle will need the ability to detect, analyze, and report emergencies to the correct authorities. However, in the case of manual aid requests, the driver will be responsible for entering data concerning the specific services needed and the relative urgency of the request. In both cases, it is important that the dispatcher be able to inform the drivers that their request for aid has been heard and is being responded to.

In the case of commercial vehicles which might be carrying hazardous materials, it is extremely important that emergency personnel be notified in advance so that precautionary measures may be taken and the correct emergency personnel can be sent.

Cross References:

Presentation of Automatic/Manual Aid Request Information

Trip Status Allocation Design Tool

Key References:

    1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).

    2. Huiberts, S. J. C. (1989). How important is mobile communication for a truck company? IEEE, CH2789–6/89/0000–0361, (pp. 361 –364). Piscataway, NJ: IEEE.

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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FHWA-RD-98-057

 

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