Traffic congestion is a big problem that only seems to be getting worse – especially as cities emerge from the pandemic.  The challenge of congestion is a perennial issue for cities in the United States and around the world.  Greenhouse gas (GHG) emissions from transportation account for about 27% of total U.S. GHG emissions, and road vehicles account for nearly three-quarters of transport CO2 emissions. Nonetheless, for-hire vehicles (“FHVs”) can be part of the solution to congestion.

The International Association of Transportation Regulators (“IATR”) has expended considerable time and effort to assess the role of regulators in deploying mandates, incentives, and/or the removal of problematic regulations that contribute to vehicle congestion. In 2021, the IATR set out to develop principles that would form a framework for best practices to support mobility policy-making for federal, state/provincial, and local governments to achieve efficient, affordable, sustainable, resilient, and equitable multi-modal passenger transportation – while mitigating the negative impacts of increased vehicle congestion in the post-pandemic world.  The project was a collaboration among regulators, regulated entities, and other stakeholders that included extensive research of literature, legislation, and regulations, workshops, focus groups, and interviews. 

Following two IATR workshops and a survey, this project culminated in the issuance of “Guiding Principles for Mobility Policy and Congestion Mitigation” in January 2023, which highlights ten solution-focused principles and a regulatory “do’s” and “don’ts” list.  The IATR identified five (5) root causes of traffic congestion: private car dependence; modal shift from public transit to personal vehicles; for hire vehicle (FHV) growth; surging e-commerce; and ineffective policies.  The IATR’s universal guiding principles are as follows:  

  1. Fair road pricing and congestion revenue policy. The use of congestion pricing or other toll roads, taxes, and fees should provide incentives for sustainability and equity goals.  For example, in New York City, this means the Metropolitan Transportation Authority (MTA) should have a meaningful policy-directed “lockbox” or designated revenue stream to use funds to meet congestion goals.  This lockbox would secure all revenue raised from taxicab and FHV passengers (NOT to be used for public transit capital costs), but rather for exclusive use as subsidies for on-demand wheelchair accessible paratransit services, as well as first-and-last-mile partnerships to connect public transit to private mobility services in transit deserts.
  1. Integration of various private modes of shared mobility with public transit to foster mobility-as-a-service (“MaaS”).  Implement incentives and disincentives to encourage multi-modal mobility provided by ride-hail, taxis, and other for-hire vehicles, micro-transit, and micro-mobility. Wherever possible, promote public-private partnerships including the development of Mobility Hubs, and use technology platforms to promote MaaS. 
  1. Maximize vehicle utilization. Identify business and regulatory solutions to increase vehicle utilization and efficiency. For example, mixing passenger and goods delivery.
  1. Deploy innovative, goal-oriented street design principles.  Explore the use of private property and off-street facilities to stage vehicles and micro-mobility infrastructure. Review curb space policies to encourage expeditious pick-up and drop-off of passengers and goods.  For example, NYC provides “carshare parking only” spaces at the curb and in municipal parking facilities through a permit system.
  1. Implement sustainable transportation incentives and disincentives. Identify incentives that would best promote the increased use of sustainable modes, such as bus lanes, preferred curb space access, and subsidies. Provide disincentives to personal vehicle usage, such as taxes, fees, and fines.
  1. Thoughtfully plan to improve and expand EV infrastructure. Upgrade and expand existing infrastructure so public transit services are real options for everyone. Develop a master plan for multi-modal ecosystems that includes public and private fast-charging stations that coincide with for-hire passenger delivery and congestion mitigation strategies.


  • Promote shared mobility.  Improve environmental outcomes through measures that increase vehicle efficiency, reduce or mitigate congestion (including deadheading/zero-occupant vehicles), and maximize the use of shared rides (e.g., pooled rides).


  1. Promote equity. Develop all policies to provide, wherever feasible, incentives and disincentives for any for-hire ground transportation services that provide services to underserved or unbanked communities. For example, exemptions from congestion pricing for low-income individuals.
  1. Promote accessibility.  Develop all policies to provide, wherever feasible, incentives and disincentives for any for-hire ground transportation services that provide services to people with disabilities.  For example, uniform systems of service delivery for subsidized public paratransit by wheelchair accessible taxicabs.   


  • Reduce the size of government fleets.  Reduce and eliminate the unnecessary purchase and use of motor vehicles for government fleets. Explore the use of taxicabs and FHVs to replace government fleet vehicles.


While implementing any of these ten guiding principles to reduce or mitigate vehicle congestion, it is imperative for regulators to remember a list of regulatory “do’s” and “don’ts,” including the following:

  • Vehicle Caps: Do provide for sound competitive growth among ride-hail, taxis, and other for-hire vehicles with proper incentives to promote equity, accessibility, and sustainability goals. Don’t implement blanket caps on the number of vehicles. 
  • Fare Over-Regulation: Do have strong policy reasons for setting minimum or maximum fares, and do ensure such policies are applied equally among competing for-hire modes.
  • Congestion Pricing: Do ensure there are viable alternatives to driving (e.g., public transit, walking, biking). Don’t implement congestion pricing policies without exploring exemptions that promote the above guiding principles. 
  • Vehicle Utilization & Management: Do encourage “pooling” of passengers, more sustainable vehicle fleets, and integration with public transport and active mobility. Don’t implement policies or regulations that lead to empty runs, including obligations for vehicles to return to a garage in between rides and geographical restrictions that prevent drivers from taking passengers on return trips from remote locations. 
  • Shared Use Zones: Do consider establishing zones within cities accessible to shared modes, including public transit, taxis, and TNC vehicles.  Don’t reduce access by prioritizing certain modes.
  • Speed Limits: Do reduce speed limits in parts of cities where such changes promote safety without increasing congestion. Don’t reduce speed limits across the board.


Matthew W. Daus, Esq

Photo above from the “Decarbonizing Transport Now and Everywhere: A Global Research Perspective” workshop session held on January 8, 2023, which was moderated by Nancy L. Vandycke of the World Bank Group (above far left at podium). The presenters, from left to right seated above:  Pascal Rossigny representing PIARC (the World Road Association) from France; IATR President Matthew W. Daus from the U.S.; Jonas Jansson representing ECTRI (the European Conference of Transport Research Institutes); Professor Chikage Miyoshi representing WCTRS (the World Conference on Transportation Research Society) from Hiroshima University, Japan; and Carlo Borghini representing the European Union (Europe’s Rail Joint Undertaking) from Belgium.


The IATR’s guiding principles for decarbonization policymaking in the passenger ground transportation sector were released in final form in Washington D.C., at a Global Decarbonization Workshop sponsored by the International Coordinating Council of the Transportation Research Board (“TRB”).   The TRB, which is part of the U.S. National Academy of Sciences, held this well attended workshop at its annual conference in January 2023, and included academics, transportation officials and mobility organizations from every corner of the globe.  

During my speech and subsequent panel discussion presenting the IATR’s decarbonization principles, I emphasized how no “one size fits all” solution exists to mitigate traffic congestion.  Also, there is “no one person or entity” that can move the needle on speeding up our global sustainability efforts. We all need to work together, across government agencies, mobility industries and modes, and in partnership with the private sector. These ten IATR principles require multi-modal implementation and suggest coordinated multi-agency governance to produce master sustainability plans reducing reliance on personal motor vehicles.  




Matthew W. Daus, Esq.

President, International Association of Transportation Regulators

Transportation Technology Chair, City University of New York,

Transportation Research Center at The City College of New York

Contact: mdaus@iatr.gobal