Background

Transportation agencies often look at highway interchanges to make cost-effective capacity improvements. Every transportation agency is responsible for numerous interchanges, each of which potentially could be upgraded or redesigned in many different ways. Complete interchange reconstruction is expensive, and all too often one large project consumes funds that could be more efficiently allocated to numerous smaller investments or to staged improvements over time. Knowing how and when to make interchange improvements, and basing that knowledge on rigorous analysis, is a valuable exercise for many DOTs.

How does an agency determine which interchange improvements are most cost-effective? How does one compare and prioritize infrastructure improvement projects across a district or an entire state? How does an agency justify and defend these infrastructure management decisions to a government official or member of the public that might prefer another outcome?

Through an effort for South Carolina DOT, the consultants at Cambridge Systematics developed the Interchange Management System to support agencies as they answer the fundamental question – How should a transportation agency allocate limited resources among competing projects?

Using the Interchange Management System, users can:

• Rank interchanges and highway segments by a number of predefined and user-determined criteria;

• Design their own improvements and upgrades; and

• Produce an initial estimate of the benefits and costs of design alternatives.

The Interchange Management System introduces a suite of rigorous interchange performance models to support statewide project prioritization and evaluation.

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Benefits

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• Objective Ranking – The system ranks interchanges by a variety of customizable performance measures, including passenger or commercial vehicle delay, safety, and cost. Agencies can combine these measures to create new performance indices and generate a statistically grounded, prioritized list of improvement projects.
• Interactive Improvement Design – Users can design and evaluate the impacts of a wide variety of proposed improvements. Click to widen roads or ramps, upgrade ramps from diamond to cloverleaf or cloverleaf to flyover, add turning lanes or collector-distributor roadways, or signalize intersection at ramp ends. As you experiment, the system quickly analyzes the improvement and predicts the performance of the upgraded interchange.
• Benefit/Cost Calculation – Would an expensive overpass make a greater impact on vehicle delay than a small lane addition? The system automatically calculates the benefit-to-cost ratio of each proposed alternative, ensuring that users identify projects that get the biggest bang for their buck.
• Rigorous Analysis – Cambridge Systematics has a proven record of setting the national standard for transportation analytics, and we are the first to invest that same level of rigor into interchange management. The system integrates proven traffic flow, interchange behavior, and user cost models (among others) to drive its management, evaluation, and prioritization processes.

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Case Studies

South Carolina – Cambridge Systematics designed, developed, and implemented the Interchange Management System in collaboration with the South Carolina DOT to help manage, evaluate, and prioritize South Carolina’s Interstate highway interchanges. This effort required the engineering evaluation of more than 240 interchanges. DOT planners are able to use objective rankings to prioritize interchange improvements, assuring that scarce funds make the greatest overall impact. Currently, Cambridge Systematics is enhancing the system to include air quality models, improved modeling of specialized interchange types, and other improvements.

Florida – The Florida DOT recently completed a pilot deployment of the Interchange Management System in the I-75 Corridor for 40 users from the Florida DOT central and district offices. The pilot effort was intended to evaluate the capabilities of the system and implement selected enhancements, including updated performance metrics, enhanced modeling of saturated ramps and queuing conditions, and handling of actuated signals and right-turn-on-red movements. Cambridge Systematics collaborated with this team of users to develop a work plan for additional enhancements in preparation for statewide deployment.

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Cambridge Systematics – Leaders in Infrastructure Management

Cost-effective management of transportation infrastructure is a critical challenge facing transportation agencies. Interchange management demands more than departmental budgeting for maintenance and repairs to bridges and roads; it requires alignment of strategies, operations, and analyses to ensure the smooth and cost-effective movement of passengers and goods.

Cambridge Systematics is a recognized leader in providing asset management services for the transportation industry – from strategic planning to management, system development to process redesign. We can help you deliver more for the dollar spent, improve collaboration among agencies, and align business processes from policy to project and service delivery, eliminating redundancy and cost in data collection and usage.

Cambridge Systematics has collaborated with the American Association of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration (FHWA), the National Cooperative Highway Research Program (NCHRP), and more than 40 states to improve the quality of infrastructure management.

In short, we are infrastructure management experts, and we bring our expertise to the table in every deployment.

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IMS Technical Specifications

• Designed for Microsoft Internet Explorer Version 6.0 or later
• ASP.NET
• Microsoft SQL Server
• Maximum number of users:  unlimited
• Supporting TRANSCAD and Integraph for GIS analysis
• Customized support plans and hosting options available

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Contact Information

William E. Robert, Principal; 617-354-0167; wrobert@camsys.com

Ruth Miller, Software Product Specialist; 617-354-0167; rmiller@camsys.com

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