Place-based streets: Getting standards correct to create public places
Communities can create better functioning streets by changing the rules for streets in their community.
Conventional street standards contained in subdivision development regulations or other development codes are often developed in isolation from the context of what surrounds it. These standards are often based solely on function and classified as arterial, collector or local. While these standards may work well for moving cars, they do poorly at creating high-functioning public places for bicycles and pedestrians.
To create streets as public spaces, a greater variety of street types – ones focused on function and urban context—need to be used. These varied design standards help reinforce the role of the street as a public space. These newer street types include avenues and boulevards, free-flow streets and roads, yield-flow streets and roads, alleys and lanes, and passages and paths. Avenues and boulevards are higher capacity thoroughfares designed to connect neighborhood centers or cerate boundaries between neighborhoods.
Avenues function to connect centers and are often designed with a terminal vista on a structure or a plaza. Boulevards tend to run along the edges of neighborhoods and carry mostly through traffic. Both have planted medians 10-20 feet wide that separate travel lanes and provide a pedestrian haven for crossing. These medians can also be used for stacking lanes for left turns where appropriate.
Higher traffic boulevards with multiple lanes in a very urban context can also have slip lanes for local traffic and parking and still maintain high traffic flow. Avenues and boulevards both have moderate design speeds of 25-35 mph to maintain traffic capacity while still maintaining a pedestrian space. The lane width on avenues should be 10 feet for travel lanes and eight feet for parking lanes, with boulevards having an 11-foot travel lane.
Free-flow streets and roads are thoroughfares that carry enough traffic to warrant a full travel lane in each direction. These street types are most commonly used for urban cores and traditional downtowns.
One of the key differences in discussions about streets and roads are their purpose. Streets are designed for access as well as mobility of cars and people. Roads are primarily designed for the movement of automobiles. As such they have very different elements within the right of way.
Roads do not have parking lanes or sidewalks, they are a rural transportation element designed to move traffic efficiently. They do not have a hard curb and may have wide shoulders to function as parking or walking areas but these shoulders are not typically constructed of hard surfaces. Free-flow streets have travel lanes of 10 feet and parking lanes of eight feet on one or both sides of the right of way. These parking lanes serve multiple uses on free flow streets. They control speeds to maintain a pedestrian friendly space but also serve as parking for adjacent parcels allowing for reduced parking on site. Parking also serves as a buffer between travel lanes and sidewalks.
Slow-flow and yield-flow streets are typically found only in residential areas of medium or lower density. Slow-flow streets are designed with narrower travel lanes such as eight to nine feet and narrower parking lanes of seven feet. Alleys and lanes function as access to private spaces and the rear of lots. These street types are one lane wide and also provide access for services such as waste and recycling pick up. Alley access also allows for an unbroken frontage of the lots allowing for narrower lots and greater density and walkability.
To fully create streets that function as places, street categories need to support different building forms so there are differing street designs to support different functions with a correct form for the place and context. Street design also has to have elements that move it beyond functioning as a hallway or corridor for moving traffic. It needs to have enclosure of the public realm and create interest by using terminating vistas or other means to create visual interest.
Michigan State University Extension offers training and technical assistance to communities that are interested in looking at creating place based streets for their community. Contact a land use educator for more information on these training programs.