What is TDM?

TDM Options“Transportation demand management” is the flip side of infrastructure. It focuses on understanding how people make their transportation decisions and helping people use the infrastructure in place for transit, ridesharing, walking, biking, and telework. It is cost-effective in guiding the design of our transportation and physical infrastructure so that alternatives to driving are naturally encouraged and our systems are better balanced.

TDM, focused on people first, functions on two levels.

At its most basic level, TDM is a program of information, encouragement and incentives provided by local or regional organizations to help people know about and use all their transportation options to optimize all modes in the system – and to counterbalance the incentives to drive that are so prevalent in subsidies of parking and roads.  These are both traditional and innovative technology-based services to help people use transit, ridesharing, walking, biking, and telework.

There is also a deeper dimension of TDM that is equally important.  TDM is a principle that should guide everything we do in designing our transportation and physical infrastructure so that alternatives to driving are naturally encouraged and our systems are better balanced.  TDM thus underlies most of the important new initiatives of today:  transit-oriented development, complete streets, walkable activity centers, livability and sustainability initiatives, and integrated corridor management, to name a few examples.

When we put these two together and offer robust TDM services in conjunction with properly designed infrastructure, we get the largest impacts and the biggest bang for our buck.

TDM graphicTDM is a strategy many places dabble in, but few have comprehensive programs. Mobility Lab believes there are seven basic parts of a robust TDM strategy that have the power to shift trips, ranked here from least powerful to most impactful:

  • Information
  • Marketing business benefits to employers
  • Comprehensive programs with mutually reinforcing services, such as transit, carpool/vanpool, bike, walk, transit stores, and other
  • Incentives for transit and alternate modes
  • Disincentives for driving, which is where parking supply and pricing, tolls, and congestion pricing come in
  • Ordinances and development conditions, and
  • Trip caps or maximum average vehicle occupancy

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Arlington’s measurement of its TDM goals looks like this:

GoalPerformance Measure
Goal 1: Influence Growth in the Use of Transportation Options
  1. Drive Alone Commute Mode Share for Arlington Residents and Workers
  2. Transit Usage in Arlington
  3. Average Weekday Vehicle Trips and Miles Reduced in Arlington by ACCS
  4. Bicycle Usage in Arlington
  5. Arlington Resident Capital Bikeshare Memberships
Goal 2: Provide Quality TDM Service to Arlington Residents, Employees, Business and Visitors
  1. Net Promoter Scores for ACCS Units
  2. Annual Fare Media Sales and ACCS Sales Commissions
  3. Number of Employers Working with ATP, by Level
  4. Percent of Employers working with ATP that offer their employees the transit benefit
Goal 3: Encourage a Culture in Arlington in which there is increased Awareness and Appreciation of Transportation Options and Benefits
  1. External employer and community events attended and number of individuals reached
  2. Resident Awareness of TDM Services in Arlington
  3. Number of Residential Units in Properties Working with ATP
  4. Resident Use of TDM Services in Arlington
  5. Awareness and Recognition of TDM Programs Available for Arlington Workers
  6. Brochures requested and distributed
Goal 4: Increase Transportation System Sustainability through TDM
  1. Greenhouse Gas Emission Reductions Attributed to ACCS
  2. Percent of Existing Site Plan Buildings with Compliant TDM Site Plans
Goal 5: Provide Transparency and Ensure Return on Investment on TDM Investment through Program Monitoring and EvaluationThis performance plan is intended to fulfill the aim of Goal 5. Arlington County Commuter Services commitment to meeting this goal is demonstrated through their commitment to producing this performance report on an annual basis.

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