Technology Overview
CAD Dispatch Center
Computer aided dispatch and scheduling (CADS) is software that incorporates transit routes, schedules, trip orders and vehicle assignments
to allow dispatchers to know where their agency’s transit vehicles are located. Many transit operators deploy CADS in order to manage their demand responsive
transit (DRT) services. DRT services are provided by transit operators to dispatch vehicles to pick up passengers and transport them to their destinations
on demand. These transit vehicles do not operate on a fixed route or schedule. The transit vehicle may pick up or drop off several passengers during the
same trip.
CADS information enables dispatchers to more efficiently dispatch trip requests, better maintain service, and respond to disruptions, emergency situations
and other issues such as a disabled bus. A CADS system is often integrated with advanced vehicle location (AVL) systems, geographic information systems
(GIS), and mobile data terminal (MDT) technologies to provide advanced real-time system capabilities.
The capability and interoperability of CADS systems may vary by agency based on their specific needs and the availability of supporting technologies.
Smaller fixed-route bus agencies may utilize basic CADS as a stand-alone technology without additional systems or integration with field equipment. Medium
and large transit agencies utilize CADS for real-time operations, dispatch optimization, scheduling, advanced planning and trip planning. It provides
a vital tool for transit agencies to organize and expedite dispatching and scheduling.
Many transit operators use CADS to assist in the management of their services, including:
- Demand responsive transit (DRT) services,
- Managing and monitoring large volumes of data,
- Ensuring that services meet or exceed service quality standards, and<
- Improving the quality of service for users.
All of this results in more cost-efficient transit systems. CADS systems deliver a wealth of data pertaining to the performance of a transit fleet, but
these systems can result in information overload for dispatchers. Dispatchers need assistance in prioritizing their workloads and discerning patterns
of operational problems.
Common Combinations
CADS systems can be combined with many technologies and are particularly important to consider alongside a comprehensive vehicle management system. CADS
systems are commonly integrated with AVL, GIS, automatic passenger counters (APCs) and data management systems. CADS may also be integrated with traveler
information systems (TIS) such as trip and itinerary planning. This benefits customers by providing real-time information similar to what is available
to dispatchers. CADS may be implemented as a stand-alone system serving such functions as basic dispatching and scheduling services. More advanced CADS
systems can be implemented and utilized to communicate with all ITS systems as mentioned above, and will react to real-time scheduling changes and dispatching
needs.
Factors to Consider
A CADS system is a useful tool that any transit agency can benefit from. Regardless of an agency’s size, scheduling and dispatching vehicles can be a
time-consuming task for dispatchers. Implementing a CADS system to automatically manage simple scheduling and dispatching enables dispatch personnel to
focus on more immediate needs. Smaller agencies may require only basic CADS capabilities, sometimes combined with a basic mapping system or basic data
management system. Larger agencies will benefit from advanced CADS systems that can handle multiple complex schedules and associated dispatching needs.
CADS can serve as the cornerstone for a comprehensive transit management system. CADS systems enable agencies to expand into other areas with regard to
maintaining communications and functionality.
CAD Block Diagram
Planning
- Develop a structured procurement plan and performance-oriented requirements and specifications.
- Visit transit agencies providing similar transportation services and discuss their CADS systems and related technologies.
Implementation
Charlotte Area Transit System (CATS)
Special Transportation Service (STS) Vehicle
- Perform rigorous testing of the entire system prior to implementation by developing comprehensive test and acceptance plans.
- Consider installing a backup system at a remote location to ensure uninterrupted CADS services in case there is a power failure in the main network.
- Develop standard data-exchange protocols between the field and the transit operations center to ensure that equipment from multiple vendors is compatible.
- Ensure all hardware is installed with virus and firewall protection.
- Expect a learning curve as drivers and dispatchers develop efficient communications and dispatching techniques.
Integration
- Develop specifications to allow open standards.
- Agencies should specify a modular implementation plan to allow for less costly maintenance activities. This will also help to simplify technology upgrades.
- CADS systems should operate on a communications backbone with sufficient bandwidth.
Benefits and Costs
Benefits
- Improved fleet situational awareness
- Schedule adherence—maximum on-time performance
- Supervisors and dispatchers are proactive in addressing operational issues
- Text messaging can improve dispatch efficiency
- Alarm monitoring to notify dispatch of emergencies
- Single point for operator log in
- CADS with AVL can provide real-time, next-bus predictions
- Comprehensive historical data collection and incident reporting
Costs
Equipment and Implementation
CADS systems need the following technologies:
- Software
- Hardware platform (server, displays, printers)
- GIS/mapping
- Voice and data communications with drivers/vehicles and with operations support personnel
Depending on the size of the transit fleet, a CADS/AVL system can cost from $100,000 to over $1 million to purchase, install, customize, implement, operate
and maintain. Transit agencies can reduce vendor costs by reducing the amount of customization in their CADS systems.
Operations and Maintenance (O&M)
Policies and procedures need to be well developed and documented, and fully consistent with the software platform. An adequate number of dispatchers are
needed, which depends on the size of the transit fleet. It is recommended that an operational plan and a maintenance schedule be implemented with any
CADS systems.
Training and Staff
Selection and training of dispatchers is extremely important. CADS systems do not run themselves; they require significant operator input. Dispatchers
need clear task-oriented objectives to keep them involved as active participants in the CADS system and not just passive observers.