Elements of Business Rules and Decision Support Systems within Integrated Corridor Management: Understanding the Intersection of These Three Components
This document reported lessons learned during the development and deployment Decision Support Systems (DSS) and associated business rules required to operate Integrated Corridor Management Systems in Dallas and San Diego between 2007 and 2017.
Business rules are generally the game rules by which agencies and neighboring jurisdictions agree to operate. In the chess analogy, a bishop can move diagonally any number of unimpeded spaces, a pawn can move one space forward, etc. With business rules that support interoperability between agencies and transportation corridors that span multiple jurisdictions, transportation can share data and resources to enhance their ability to monitor and predict traffic conditions, and provide actionable information to motorists.
DSS are primarily computer-based information systems and algorithms that can sort, rank, or choose alternative response actions in response to recurring and non-recurring congestion across a transportation network. DSS generally consists of three components:
- Expert rules (configuration)
- Prediction capabilities (modeling)
- Evaluation (analysis)
DSS can support real-time operations as well as strategic planning over the long term to support several types of ITS applications including, but not limited to:
- Accident response strategy assessment
- Online travel information systems
- Predictive travel time calculations
- Dynamic route guidance
- Adaptive ramp metering using predictive traffic congestion algorithms
- Intelligence-based Transit DSS
- Dynamic emergency vehicle routing
- Emissions management
- Urban and interurban congestion management
- Security threat mitigation and large-scale evacuation management.
Agencies should build on existing institutional arrangements in an attempt to build consensus, developing clearly defined roles and responsibilities along with tempered expectations. Within these boundaries, establishing clear business rules as part of the decision process can facilitate operations.
The following lessons learned were highlighted as recommendations to enhance DSS for regional integrated corridor projects.
- A DSS may not take into account certain jurisdictional rules about what can be communicated to travelers (some jurisdictions do not allow for direct diversion messages with instructions to be communicated, instead favoring less specific messages). This can have a major impact on the efficiency of a traveler information dissemination strategy recommended by a DSS.
- Many jurisdictions may restrict truck use on certain roads. A DSS that has not incorporated this information and interagency agreements regarding truck traffic would not differentiate the traveler type. A properly calibrated DSS should incorporate this into the recommendation protocol to separate out vehicle travelers from truck traffic in any diversion or messaging suggestion.
- There could be local jurisdictional constraints on the use of traffic signals and diversions at certain times. For example, in San Diego there were safety concerns about traffic being diverted past schools around school start and end times. These concerns and restrictions are contextual constraints of the chess board that the DSS should be accounting for when providing recommendations.
- For traveler information posted to dynamic message signs, there are often regulations regarding the structure and format of messages. This should be incorporated into the DSS recommendations. Although constraining the message content and structure to conform to local signs and protocol is likely part of the DSS development, additional rules for types of messages and phasing frequency based on traffic speed may be the type of agreed upon use that is not usually incorporated.
- Something as simple as traffic management center (TMC) staffing is another area where not all jurisdictions operate in the same way. Recommendations should incorporate whether staff from other facilities are available to coordinate with (and if not, is thee another representative or agency that the responsibility rolls to) would enhance the need for operator review and adjustments.