TOWARDS A PROGRESSIVE TRAFFIC ENGINEERING MANIFESTO: Values and Priorities To Guide 21st Century Road Work

The “spirit” of a law or policy is really just as important as its “letter”.  The frame of mind – the professional culture – of those implementing a policy, their underlying values and assumptions, will shape their decisions and actions just as much as the words. Nearly a decade ago, one of my first LivableStreets blogs, Traffic Engineering Myths Revealed, explored what seemed to be the car-focused, Interstate-derived consensus among road-design professionals.  Today, while transportation policies have radically changed, too often much of the old designs still infest road projects.  It’s time to promote an explicit and short description of a more progressive vision.

Here is a rough outline of what I think should be in a short summary of the framework for 21st century traffic engineering.  As you can tell, much of this is drawn from past blogs.  This is just a start: what do you think should be added?



Over a decade ago, when a bunch of us were beginning to discuss the connection of transportation to the other issues we cared about, it was really important to understand the assumptions and values of traffic engineers.  We would say “safety” and so would they; we would say “context sensitive” and so would they.  And then the designs they would propose would bear no resemblance to what we thought we were all talking about.  Jeff Rosenblum, co-founder of LivableStreets Alliance that grew out of those conversations, wrote up some notes based on his observations that I eventually expanded into one of my first blogs:  Traffic Engineering Myths Revealed.  It was a short version of what was underlying the thousands of pages of technical specifications in national and state road design standards documents.

Over the intervening years a lot of people have written good essays describing alternative visions. And we now have numerous progressive technical documents describing more people-centered ways of designing roads, intersections, bridges, and inter-modal connections – NACTO, Dutch Crow, even some US city and state guidelines.  The language of many of these guidelines, however, seem to always be general enough that traffic engineers are able to incorporate gestures towards a new paradigm without fundamentally changing what they’ve always done.  They are still operating under the old assumptions.

So, to help push things forward a bit more, it might be time to compile a list of the assumptions, values, and ideas shaping what we want to see. Although the final implementation of a transportation system is influenced by a lot of things besides culture, ideas count.  The following starts with some overarching or “meta” themes about transportation and society then delving into some more transportation-oriented general statements, including an occasional dive into almost technical specifics.



  • Mobility Is Not The Only Goal
    Moving people and things is the function, but not the most important goal or effect of transportation systems: transportation needs to be designed and run in ways that create more livable and prosperous communities for all groups, expands opportunities by prioritizing the needs and aspirations of those most harmed or unserved by past decisions, and minimizes negative environmental impacts through its materials or construction or use.

Travel Is The Least Important Thing About Transportation

  • Transportation Must Be Imbedded Within a Larger Program
    Transportation’s effects go beyond mobility to the entirety of a community’s life, meaning that the “external” implications of a transportation project are just as important as the “within project scope” elements; also meaning that every transportation project must be seen as just one part of a broader package of policies and initiatives that may require pre-project planning and coordination among a variety of agencies: e.g. the gentrifying effect of improved roads or other public investment needs to be countered with community stabilization programs.

Stabilizing Equitable Communities:  Gentrification, Displacement, and Markets

  • Transportation And Land Use Are Conjoined
    Transportation and land use are symbiotic forces, both shaped by and shaping the other; smart-growth zoning and other land use incentives or controls are as important as transportation planning in determining mobility needs and solutions.

Redefining Transportation:  From Moving Vehicles to Place-Making

Three Legs of a Healthy Built Environment:  Smart Growth, Active Transportation, Human-Scale Architecture

  • The Right of Way Is Public Land
    The ROW is the largest physical asset most cities own, and must be available for a variety of social uses rather than reserved for transportation and vehicle storage; commerce, socializing, play, and other purposes have equally legitimate claims to its use.

Streets Are Public Property:  Revitalized Streets are a Lever to Revitalize Public Life

  • Car Level Of Service Measurements Are A Dead End
    In most urban areas, new development is a major trigger for environmental reviews and resulting remediation or mitigation efforts, which often focus on transportation issues.  Basing the required actions on reducing car Level of Service (LOS – which is mainly based on how long it takes to get through an intersection) creates new problems rather than solving them. (In fact, using LOS as a key metric is a bad idea for almost any purpose.)  There are better ways.

Moving Beyond Car Level of Service (LOS):  Measurable and Meaningful Criteria for Transportation Investments,  Project Designs, and Development Mitigation



  • Cars Are Both Un-Ignorable And Not Enough
    We can’t ignore the history of encouraged sprawl and the billions in car-focused infrastructure investment that leaves many people dependent on their cars, especially low-income or rural/suburban families.  But for reasons of personal and public health, energy efficiency, environmental protection, and local economic development, we need to provide efficient, affordable, convenient, and attractive non-car alternatives to the maximum extent possible.  Transit can cover a limited number of high-demand corridors, although partnering with car-share programs increases the range and flexibility.  Walking is wonderful, but only for short distances.  Bicycles and the huge variety of “micro-mobility” machines now emerging can fill the gap.

Roads Shape Economies:  Why Rethinking Highways Will Make or Break Local Job Opportunities and Community Well-being

Transit Financing:  Why Saving Public Transportation Requires Helping Car Drivers

  • Road Construction Can’t Cure Congestion
    It is impossible, in today’s urban environment, to reduce traffic congestion by road construction or improvements: mass transit (particularly improved bus service) and non-car alternatives (bicycles, walking, scooters, and other muscle or battery-based mobility tools) – along with smarter growth patterns – are the only viable strategy. However, contrary to expectation, removing a highway does not automatically create congestion on the remaining roads.

Bus System Improvement is Key to Transit:  Local, Improved, Express, and Bus Rapid Transit

Traffic Congestion:  Why It’s Increasing and How To Reduce It

If You Build It They Will Come, But What Happens If You Take It Away?

  • Improved Bus Service Is The Road To Better Transit
    To paraphrase Enrique Penalosa, the more congested a road the better it is to replace car lanes with dedicated bus service, assuming that the quality, frequency, speed, and affordability of the bus service is ramped up to meet the demand.

High Status Bus Rides:  Does Bus Rapid Transit Make Sense for Massachusetts?

Why BRT is NOT a Subway

  • Curb Space Usage Needs To Change
    Until we de-throne parking from its privileged position as a priority use of street space, we will never be able to be flexible or effective about improving mobility on urban roads.  A radical rethinking of our use of curb space is inescapable given the massive increase of on-call vehicles and home delivery of on-line orders, the need to reserve space for store deliveries and handicapped or elderly drivers, the necessity of providing more parking spaces for bicycles and various electric “micro-vehicles”, and the safety measure of leaving more open space at intersections.

Circling the Block:  Saving Time, Space, and Money Through Parking Reform

Digital World Creates New Road Functions & Requires New Design Standards

  • The Digital World Will Change But Not Improve Our Lives
    New technology will not solve our problems: technology is a tool; better planning is the solution.

Smart Cities, Power Politics, and Quality of Life:  Technology and what it’s used for

AVs -- the Second Coming of Cars?

Are E-Bikes Bicycles?  Does it matter?



  • Interstate Lessons Stop At The Off-Ramp
    The Interstate system is wonderful, until it tries to go into cities; urban (and suburban town-center) roads require a completely different set of design rules for both commercial and residential areas, as do rural roads; these differences will only increase as new technologies and vehicles come on to the roads

Suburban and Rural Infrastructure: Fitting the Design to the Location

  • Speed Kills
    Slowing vehicles (and eliminating large trucks) is the key to safer streets: contrary to Interstate design rules, this requires eliminating the extra space and other design features that provide a “margin of safety for driver error” It should feel uncomfortable to drive faster than safety allows.  In fact, the comfort of non-driving co-inhabitants of the public right of way should determine the “target speed” that shapes the road design -- it is the condition of the road that sets the speed people actually drive, rather than the posted limit.  So, for every road project, an analysis of what is happening around the round and the non-car uses of the road should be done to determine a desired or “target” speed.  Then the road should be designed to make it uncomfortable to go faster than that – typically 20 mph in residential and commercial areas -- using narrow lanes, humps, car speed feedback signs, lots of stop signs, plantings, raised crosswalks/intersections and curb extensions (so long as they don’t interfere with bike lanes), or other features. 

Slowing Traffic to a Target Speed: How To Make Our Streets Safer

The Magic Bullet of Safer Roads: Narrower Lane Widths

The Dangers of Safety:  Why Focusing on Car Accidents May Hurt Our Health

  • Bikes And Other Slower Vehicles Need Low-Stress Networks
    Where motorized traffic is heavy, fast, or mostly trucks, separate facilities for bicycles and pedestrians (e.g. protected bike lanes, raised intersections and cross walks) are necessary to create low-stress networks; but road structure is not enough: while everyone’s and every vehicle’s safety is important, priority must be given to protecting the most vulnerable – pedestrians, bicyclists, slow movers, children, anyone not protected by tons of metal: for this, new laws are needed.

People Priority Streets: Neighborways, Slow Streets, and Safety Zones

Better Bike Lanes: Improving on What Got Us Here

Vulnerable Road User Protection Laws: “Whoever can do the most damage has to be the most careful”

  • Respect Desire Lines
    Pedestrian crossings and curb cuts should be placed along desire lines rather than some arbitrary distance from the corner.  Busy intersections with traffic lights should provide a 3-5 second “leading pedestrian interval” (LPI) and non-turning bicyclists should be allowed to go on the early “walk” signal.  Except in extremely rare situations, the total “walk” time should be long enough for a slow-moving elderly person to get across the entire intersection rather than to a “refuge” in the middle.  If there is a “countdown” indicator, it should be as long as possible – including the LPI plus the full green-light until the traffic light goes through the yellow and turns red.

Walk Signal Time and other thoughts

  • Use Stop Signs Rather Than Traffic Lights
    Traffic signals should be only used where absolutely necessary; four-way stop signs are more effective (and cheaper!).



  • Balance Boldness With Public Process
    A balance needs to be found between public input and disruptive innovation, between mobilizing a constituency for improvement and unleashing change-fearing NIMBYism, between doing all the studies and just giving something a try.

Follow The Leader: Lessons from NYC’s Janette Sadik-Khan

Improving City Life by Unleashing Citizen Creativity Through Government Initiative:  Quick, Visible, Removable

Effective and Democratic City (and Transportation) Planning:  Neither Top-down Nor Bottom-up is Enough

  • The Private Sector Has Different Interests Than The Public Good
    Public-Private-NonProfit Partnerships are a powerful but easily misused strategy.

The Varieties of P3s:  Privatizing, Contracts, and Special Arrangements

Public-Private Partnerships (P3): The Priority Must Be Enhancing Public Value

  • Culture Eats Policy For Breakfast
    Professional transportation engineering culture needs to change: In practice, culture trumps (sic) policy nearly every time; while there are a lot of new voices in the field pushing for change the old assumptions still dominate.

Closing the Gap: Transportation Policy vs. Engineering Practice



Northeastern University professor Dr. Peter Furth summarizes his core values and priorities this way:

Transportation needs to be designed, constructed, and used in ways that promote sustainability in 5 dimensions: planet, human health (both exercise and injuries), human happiness (including being happy enough to have and raise kids), community (transportation should support community function), economic prosperity

1) Reducing auto dependency --

  1. a) Offering people sustainable transportation choices for most trips that are realistic and attractive.
  2. b) Pricing and regulating auto travel to reflect its true, long-term cost to society
  3. c) Siting homes, jobs, shopping, and other land uses to support sustainable transportation.

2) Making the transportation system safe. This mostly has to do with making streets less of a safety problem / safety barrier.

3) Using transportation investments to create good places for community. Transportation investments are often connected to parks, urban design, and other aspects of community that go beyond the pure transportation function. Use investment levers to get the whole package.


Thanks to Jeff Rosenblum, Peter Furth, and Charlie Denison whose ideas have shaped my own over the years.





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