Forced Slow Down: Road Diet Vocabulary for Neophytes

This article first appeared in Driving Freedoms Fall 2018.

Changing speed limits is not the only way cities try to slow down traffic. Around the country, motorists face numerous obstacles that attempt to restrict traffic flow even beyond the street’s stated speed limit.

According to the Federal Highway Administration (FHWA), a classic road diet is usually a converted four-lane, undivided roadway segment, cut down to a three-lane street with two car lanes and a center two-way left-turn lane. The space originally occupied by the fourth lane then becomes fair game for a bus lane, pedestrian islands in crosswalks, bike lanes, sidewalks, bus shelters, parking or even landscaping elements. Utilizing the nonprofit Smart Growth America’s Complete Streets philosophy and terminology (see below), the FHWA advocates for road diets on the national level.

A number of different transportation philosophies have permeated the transportation planning sector, which is often the reason for the war on the 85th percentile rule to determine safe and reasonable speed limits.

Vision Zero, for example, promotes lower speed limits and encourages road diets. Vision Zero is a strategy to eliminate all traffic fatalities and severe injuries, while increasing safe, healthy, equitable mobility for all. First implemented in Sweden in the 1990’s, Vision Zero programs are spreading across the world at great cost even though none have realized anything close to the stated goals. More than 35 US cities have adopted Vision Zero principles.

The nonprofit Smart Growth America’s National Complete Streets Coalition became a partner with Vision Zero proponents just last year. Complete Streets promotes a transportation and design approach that requires streets to be planned for road users of all ages and abilities regardless of their mode of transportation. In October 2017, over 1,140 agencies at the local, regional and state levels have adopted Complete Street policies.

Smart Growth is an approach to development that encourages a mix of building types and uses, with diverse housing and transportation options in neighborhoods and involves ongoing community engagement. Smart Growth America has laid out 10 principles that encourage urban planners to design neighborhoods that are for mixed use, compact and walkable with less need for vehicles.

Living Streets has an objective similar to Complete Streets. Its mission statement is “We envision streets as living public spaces that connect people to places and to each other.” Based on the Dutch Woonerf concept, the Living Streets concept is evident in many European cities.

Complete Streets and Living Streets approach the issue of transportation differently. Complete Streets accommodates each mode of travel in its own defined space, which includes bike lanes, sidewalks, and bus lanes. The design and posted speeds are generally based on the 85th percentile. However, some urban areas are reducing speed limits to a uniform level of between 15 to 25 mph.

Living Streets, a recent approach new to the US, is based on personal, not vehicle mobility, and provides multiple ways for people to travel in a shared space. All modes of transportation are free to move without physical barriers. Distinct separation of modes of travel, pavement marking or signage defining space denote limitations. Even though no mode dominates, the safety and mobility of people is the fundamental starting point.

Traffic calming puts physical impediments in place on existing roads to reduce vehicle speeds. The Institute of Transportation Engineers defines traffic calming as the combination of measures that reduce the negative effects of motor vehicle use, alter driver behavior, and improve conditions for non-motorized street users. Traffic calming can be implemented on single streets, single intersections, entire neighborhoods or city-wide. Some examples of traffic calming include:

  • Vertical Deflections: speed bumps/humps, speed tables, and raised intersections.
  • Horizontal Shifts: physical barriers that do not allow drivers to drive in a straight line down a street or a road design that narrows the width of the travel lane.
  • Street Closures: The use of median barriers that reduce cut-through traffic in one or more directions.

Motorists around the country are negatively impacted by efforts to make road diets and traffic calming de facto standards. Drivers need to speak up before we are overrun with costly Vision Zero programs that have yet to be proven effective in actual practice.

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One Response to “Forced Slow Down: Road Diet Vocabulary for Neophytes”

  1. Tom McCarey says:

    “Smart growth” is a failed-for-40-years Soviet style Socialist central-planning tool to control the population and take away our freedoms. The planners where you live subscribe to this travesty and have no intention of letting you make any decisions as to what is right for you. They are so smart, they know better, don’t you know.
    The Vision Zero (et al) people loathe the freedom that your privately owned car brings you. They are furiously fighting to outlaw the internal combustion engine, for starters. If we don’t start pushing back with all we’ve got NOW we soon will be watching movies of people freely driving around, and wonder, “What was that like? Looks like fun! What a time that must have been.” The anti’s mean business, are well funded, and have the politicians on board. It will take a gargantuan effort to stop this garbage.