Streets, Roads and Stroads

Stroad is a word coined by Chuck Marohn. It is a combination (portmanteau) of the words street and road and is used to describe places that have features of both.

Here’s Chuck:

The value of a road is in the speed and efficiency that it provides for movement between places. Anything that is done that reduces the speed and efficiency of a road devalues that road. If we want to maximize the value of a road, we eliminate anything that reduces the speed and efficiency of travel.

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The value of a street comes from its ability to support land use patterns that create capturable value. The street with the highest value is the one that creates the greatest amount of tax revenue with the least amount of public expense over multiple life cycles. If we want to maximize the value of a street, we design it in such a way that it supports an adjacent development pattern that is financially resilient, architecturally timeless and socially enduring.

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Streets are the spaces between buildings. Streets have intersections with crosswalks. They have sidewalks which provide access to property, homes and businesses. Streets have cyclists and transit. They have cars pulling over to park, or pulling out from side-streets, and buses stopping and starting.

Roads connect places: they get you from a-to-b. They have minimum distractions on the side, hardly any intersections and are wide enough for little course corrections at speed. Think of “the open road”, even rail-roads.

Your journey time along a road is definitely set by your top speed, because stops are rare.

Your journey time through streets is not set by your top speed, but by the number of stops you have to make (whether at an intersection, or a bus stop, or at a shop window).

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In engineering terms, streets must have a low design speed (40km/h - 25mph, or even 30km/h - 20mph) because many users will frequently be stopping, because some users will have low acceleration and top speeds, and because there are vulnerable road users around. This means streets should have travel lanes of 10 feet, or 3 meters, wide, or narrower. They can have tight corners that force vehicles to slow.

Designing a street to encourage high speeds (with multiple wide 12 foot, 3.6m, lanes, larger corner radii, full clear sides) is dangerous madness. But it is the standard design for collectors and arterials across North America, because traffic engineers believe more space means safer streets. Since more space means higher speeds, this is clearly false. The US Federal Highway Agency admits this is problematic:

Frequently, roads and streets designed for a particular speed appear suitable for much higher speeds. Drivers read the road, not the design plans. Some roadway segments, such as a long straight section, look the same regardless of designated design speed. When these features are combined with over-designed speed sensitive features (i.e., from using above-minimum values as recommended by highway geometric design policy) the visible cues on appropriate speed may be in sharp contrast to the designated design speed. What was contemplated by the designer as a factor of safety (with respect to the designated design speed) is often negated by driver speed choice. The differing perceptions of speed by designer and driver are especially problematic where a single minimum-value feature (e.g., minimum radius curve) is located within a segment that generally has an inferred design speed much higher than the designated design speed. This condition is contrary to the design objective of “design consistency.” However, the Green Book includes no specific design criteria for design consistency and the condition described technically complies with the geometric design policy.

Stroad design saps wealth from surrounding streets, kills people and discourages all modes but private automobile travel. It is an outdated design methodology. This blog shows plenty alternatives: ignorance is no excuse.

Businesses sometimes worry about loss of through-traffic and loss of parking. But if your arterial is 100 feet or more wide, you can convert it to a multi-way boulevard or a complete street that removes no car access while enabling the other more land and tax-efficient travel modes. And improving the pedestrian realm must improve custom at those businesses. This, surely, must be politically feasible.

Stop building new stroads, and get to work converting existing stroads to boulevards, now.

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