How walkable are our sidewalks? Principles for measuring the Level of Service for pedestrians.
How walkable are our sidewalks? Principles for measuring the Level of Service for pedestrians.
Because the pedestrian experience entails much more than simply a “commuting” function, it is important to be able to identify the elements that distinguish a good pedestrian environment from a poor one. Below it is described and illustrated eleven specifics evaluation measures that highlight certain important aspects of pedestrian facilities to take care about. These concepts are drawn from Jaskiewicz (2000).
Enclosure/Definition
The principle of enclosure measures the degree to which the edges of the street are defined. Good enclosure dictates that the pedestrian’s eyes are focused along the street rather than among the blank spaces between, behind, or in front of buildings. Commercial streets best demonstrate enclosure when buildings are constructed side-by-side along the sidewalk, minimizing the volume of empty space between and in front of buildings.
A pedestrian on the well-enclosed street is greeted by a continuous row of pedestrian-scale storefronts, while a pedestrian on the poorly enclosed street is met by an overabundance of empty space—mostly parking lots—and is dwarfed by the vast distances between interesting elements.
Residential streets, especially those comprised mainly of single-family dwellings, derive enclosure primarily from street trees rather than from structures. Street trees enable the roadway to retain definition even given the larger setbacks and greater building spacing typical of purely residential areas as compared with commercial or mixed-use town centers, so long as these elements are consistent along the corridor.
Good enclosure has positive impacts on safety as well as on aesthetics. Streets that exhibit a high degree of enclosure convey a feeling of narrowness to motorists, which induces them to drive slowly and carefully for fear of collision with solid objects framing the roadway. Conversely, wide-open, unconstrained spaces invite high speeds, creating hazardous conditions for children at play as well as for pedestrians and bicyclists.
An additional pedestrian safety benefit of good enclosure is that buildings located continuously along the sidewalk provide “eyes on the street” which discourage criminal activity. A side-by-side arrangement of buildings also limits the number of dark, scary hiding places between structures that are difficult to monitor, and reduces the overall number of escape routes available to aspiring criminals.
Complexity of Path Network
A complete/complex path network furnishes pedestrians with numerous route choices between origins and destinations. In other words, a complex path network ensures a high degree of connectivity between activity centers and residential units. Without a complex path network, pedestrians are often held hostage to the same route day after day, making even the most pleasant of paths very tiresome.
A poorly connected path network, in addition to its failure to provide adequate alternate routes, in many cases funnels pedestrians onto a single circuitous path that does not typically represent the shortest distance between two points. Unfortunately, when public infrastructure is not designed to preserve a reasonable density of pathways through an area, the shortest distance, and all tolerable approximations thereof, are often cut off by private property. Such a condition is very frustrating to pedestrians and, for obvious reasons, does not encourage walking as a viable alternate form of transportation.
Building Articulation
Storefronts and houses add interest to the pedestrian experience through the varied application of materials, design, color, and décor. The best examples are found in historic town centers and close-in neighborhoods where structures were originally designed to appeal to slow-moving pedestrians rather than to high-speed automobile traffic, since walking was for a very long time the dominant form of transportation between homes and businesses.
Conversely, in most contemporary strip mall corridors, structures and billboards are designed to appeal to high-speed vehicular traffic rather than to low-speed foot traffic. Pedestrians along such routes are forced to view corridor elements at a slow pedestrian pace rather than at their intended “read speed” of 35 to 50 mph, which makes for a very monotonous and unchanging walk. Additionally, strip mall businesses typically rely on aggressive signage and ample parking—as opposed to architectural detail—to attract the attention of passersby.
Complexity of Spaces
Frequent variation in the orientation and character of public spaces adds to the general level of interest of commercial districts and residential neighborhoods. Such spaces include courtyards, plazas, parks, and playgrounds. Natural elements, such as water features and indigenous trees, can be celebrated within these public spaces to help draw attention to the unique physical qualities of a particular area. The geometrics of public spaces should be such that interesting and rapidly changing views are facilitated.
The presence and variation of public spaces along pedestrian routes ensure that long walks are broken up with occasional sectors of heightened interest.
Overhangs/Awnings/Varied Roof Lines
The degree to which items above street level contribute to the experience at street level, in terms of both aesthetics and functionality, is a very important aspect of pedestrian planning. In terms of appearance, the presence of overhangs, awnings, and varied roof lines enhances the pedestrian experience in the same manner as does the articulation of buildings through diverse materials and décor, contributing variation and aesthetic quality.
From a functional perspective, overhangs and awnings contribute to pedestrian comfort by providing shade from sunlight and shelter from rainfall.
In residential neighborhoods, this category of evaluation is not typically applicable, due to larger standard setbacks and wider spaces between buildings as compared with town center commercial districts. In the former, street trees often perform many of the functions of overhangs and awnings.
Buffer
The presence of a “buffer zone” between pedestrians and moving vehicles greatly enhances pedestrian safety and comfort. Buffer improves actual safety through the placement of solid objects between moving vehicles and people, reducing the likelihood that a collision involving a pedestrian will occur. Perceived safety, which is roughly synonymous with pedestrian comfort, is likewise increased as the buffer zone is enlarged and solidified because pedestrians along the improved corridor would feel as if their chances of becoming involved in a collision have been lowered.
Minimal buffers entail narrow landscaped strips intended merely to provide spacing between the sidewalk and the roadway. The addition of large street trees to landscaped strips exponentially increases their value as buffers. In busy commercial districts, buffer is often facilitated by parallel or diagonal on-street parking which, given sufficiently high occupancy rates, serves as a continuous solid barrier between pedestrians and fast-moving vehicles.
Shade Trees
The presence of shade trees improves the comfort level of pedestrians on hot summer days. Shade trees are effective at keeping pedestrians cool as well as blocking the sun from their eyes. Additionally, shade trees add a nice aesthetic element to the street and contribute to definition and buffer. In some cases, street trees also provide shelter from rain (but not during lightning storms, of course).
Transparency
Transparency addresses the transition between the public space and private space. In business areas, transparency is created through the use of windows, outdoor displays, and sidewalk cafes. In residential areas, front porches facilitate a smooth interface between the public street and private house.
Such transitional elements bring the public and private realms within clear view of one another, allowing passing pedestrians to get a feel for the private space without having to enter each individual building. Structures that greet the public realm with blank, windowless walls or twelve-foot-high fences typically garner low scores for transparency.
Physical Components/Condition
For obvious reasons, the overall physical condition of sidewalks and streets profoundly impacts the quality of the pedestrian environment. Areas containing no sidewalks at all typically receive the lowest possible ratings in this category, except in the rare cases where streets themselves are designed to serve as safe, shared travelways. Low ratings are also assigned to areas with broken or cracked sidewalks, disproportionately narrow sidewalks, sidewalks having trees or poles obstructing the walking path, or sidewalks that collect and retain unreasonably high volumes of standing water during rainstorms.
Vehicular Speed
As previously mentioned, vehicular speed greatly affects the actual and perceived safetyof pedestrians along a roadway. Speed is influenced by many factors, the least of which is probably the posted speed limit. Although enclosure, as facilitated by buildings and street trees, has a great deal of influence over driver speed, so does the physical design of the roadway itself.
Roadway design speed, not posted speed, is the most influential factor in determining roadway operating speed. In general, the following factors encourage slow speeds and hence serve as positive influences on the overall pedestrian environment: Narrow lane widths, Narrow overall paved widths, Broken sight lines, Sharp turns, On-street parking, Treatment at pedestrian crossings.
Lighting
The level of lighting along the street also has considerable implications for pedestrian safety—in terms of both criminal activity and protection from vehicles. Lighting standards for residential areas are often lower than those for commercial areas due to their having less background clutter against which pedestrians are difficult to see.
Street lights should be placed such that they discourage crime in addition to guarding against pedestrian/vehicular conflicts. In addition to maintaining minimum standards along the corridor, lights should be located so that the number of potential “hiding places” along the corridor—unlit plazas, parks, alleys, and other dark spaces— are minimized.
References
Jaskiewicz, F. (2000). Pedestrian level of service based on trip quality. Transportation Research Circular, TRB.
