Maximum Mode Shift

A vehicle miles traveled reduction study

Achieving climate, livability, and safety goals requires a significant shift away from driving to telework, transit, bicycling, and walking.

This study estimates the maximum amount of mode shift possible given existing transportation infrastructure, land use, and travel patterns. Unlike travel forecasting models, this project does not model changes to the transportation system, population size, or where people live, work, shop, and travel. By analyzing the current system, the project estimates the baseline potential for behavioral changes alone to reduce vehicle miles traveled and increase the share of trips made by walking, transit, or biking.

The outcomes of the study can then help guide infrastructure and services investment to support that behavioral change, while filling the gaps in the transportation system to make even greater shifts possible.

Purpose

  • Understanding how much travel can be shifted away from driving and towards other, less carbon-intensive modes, with land use, transportation system, and travel patterns held constant.
  • Learning how and to what extent the potential for mode shift varies across regional geographies, including: community types (urban, suburban, rural), transit market areas, or trips to / from job and activity center.
  • Studying the potential for, or cost of, mode shift vary across demographic groups (age, gender, income, disability status, race).
  • Examining which types of trips (errands, commutes, etc.) are most and least conducive to mode shift.
  • Exploring how mode shift potential has changed over time.

Analysis

The study analyzed the 500,000+ real-world trips reported by residents in the 2019 and 2021 Travel Behavior Inventory surveys where detailed origin and destination coordinates are available. The study will develop two key measures: mode shift potential, the percent of trips and vehicle miles traveled that can be shifted to other modes; and the time cost to individuals and households of shifting modes.

  1. For each car trip, calculate the best possible walk, bike and transit paths based on the observed origin, destination and timing. Validate against observed routes and local experience.
  2. Determine whether the transit, walk and bike options are feasible. An option is feasible if we observe a substantial number of people using that mode under similar circumstances.
  3. For trips with one or more feasible non-car options, identify whether one or more of the non-car options has a competitive travel time. An option is competitive if its travel time is within 15 minutes of the travel time by car.
Using the real-world, detailed data from the Travel Behavior Inventory allowed for an analysis across trip purposes, geographies, and for a variety of demographic variables (race, income, age, disability status).
 

Conclusions

In the Twin Cities region today, 25% of vehicle trips or 4.5% of vehicle miles traveled could shift to walking, bicycling, or transit with travel times within 15 minutes of driving.

If we made it safe and comfortable to walk and bike everywhere it is legal to do so, made e-bikes available, doubled transit service, and reduced car speeds; 50% of vehicle trips or 16.5% of vehicle miles traveled could shift.  

  • Biking has the highest potential for mode shift. This potential can be further enhanced by building safe and comfortable bike infrastructure on all streets, but more work is needed to assess the extent to which this potential can be realized.
  • Short trips have much higher mode shift potential.  Compact land-use can provide a double-benefit of higher mode shift potential and shorter trips for those that remain in cars and is necessary to achieve greater VMT reduction.
  • Vehicle electrification policies can be targeted towards travelers least able to switch modes. Even with broad changes to transportation infrastructure and service, many trips remain that cannot competitively shift. 

Find additional outcomes and data in this presentation. If you need this information in a different format, please contact the project manager below.

The full report will be posted here when it is final.

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