Complete Streets

Complete Streets

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Overview

A Complete Street is a roadway designed to safely accommodate all users - pedestrians, bicyclists, motorists, transit riders, and those with a disability. For decades, traffic engineers have designed streets, particularly urban arterials, primarily for the efficient movement of private motor vehicles. Residents across the U.S. are demanding street features that consider the needs of other users.

The complete streets framework includes not only retrofitting existing streets to increase safety for all, but changing design standards so that streets are designed with all users in mind from the outset. A related concept, Context Sensitive Solutions , emphasizes designing roadways for those most likely to use them, given the adjacent land uses and population of likely users.

Street Classifications Drive Overdesigned Streets

Since World War II, U.S. street design standards have gotten away from traditional street grid pattern that disperses traffic more evenly. Instead, the use of a street hierarchy has been emphasized. Streets are classified into a system of increasing volume and speed: residential, collector, minor arterial, and major arterial. This classification philosophy, enshrined in professional manuals such as A Policy on Geometric Design of Highways and Streets (the "Green Book") [1], purposely de-emphasizes accommodations for users other than private vehicles on the highest volume streets. Although the Green Book has been revised over time to encourage all modes, the street hierarchy approach tends to lock into place the private-vehicle bias, leading to over-design of streets to accommodate ever higher volumes and speeds during the few congested hours of the day.

Major arterials typically space pedestrian crossing opportunities up to a mile apart, ignore the needs of bicyclists, and may not even provide sidewalks or anything more than a sign on a pole for a bus stop. Speed "limits" are set by measuring prevailing speeds and establishing the 85th percentile speed as the posted limit. As vehicle technology improves and vehicles travel ever faster, the speed limit is correspondingly ratcheted upward.

Little wonder then that pedestrian and bicycle deaths and injuries occur in such high numbers on urban arterials. Another result is that the sterile, hostile environments of urban arterials carve up neighborhoods, separate shoppers from available parking and school children from their schools. This type of environment creates a natural incentive to combine as many products and services as possible into a single destination. Hence the big box mega-stores such as WalMart, that offer everything from groceries to snowmobiles.

Complete Streets Policies

Since the early 2000's, state laws, local ordinances, and regional transportation funding agencies have begun a quiet revolution, adopting Complete Streets policies (though not usually using this term). Such policies are not one-size-fits-all, and need not be threatening to traffic engineers. They generally require that, depending on the context, roadway construction projects must include consideration of its various users. For example, disabled access on a rural highway project may not be the best use of limited funding when urban streets competing for the same funds lacks similar accommodations.

In 2005, the Complete Streets Coalition was formed to advocate for and track the adoption of Complete Streets projects, as well as state and local Complete Streets policies and standards. The coalition points as models to the Massachusetts Highway Department's Projectd Development and Design Guide [2] and the City of Charlotte, North Carolina's Urban Street Design Guidelines [3]. Importantly, both models include additional staff training and revised public processes to include input from all users in making street design decisions.[4]

Implementing Complete Streets

Implementing Complete Streets policies involve four major changes [4]:

1. Revised roadway policies and standards -- These include such features as lane widths, design speeds, corner turning radii, the placement and design of crosswalks, incorporation of countdown timers, lead pedestrian intervals, bike lanes, and whether to add or leave street parking.

2. Revised decision process -- All users should be consulted to help determine the appropriate design for a new or rebuilt roadway.

3. Staff training -- Local traffic engineers and planners should receive training in best practicees for accommodating all users. Most engineering schools provide no training on traffic calming, pedestrian, bicycle, or disability design.

4. Data collection -- Data on all users, not just vehicles, should be collected before and after a street retrofit. Consideration should be given to adopting multimodal performance standards, known as Level of Service standards, to track how well each user group is being served. Typically, Level of Service is only measured for vehicles, during the most congested hours of the day.

Design Techniques

Roadways considered to be "complete" are not of any one size or description. However, when focussing on urban arterials, a number of standard design techniques are typically used:

Speeds are reduced to be more compatible with pedestrians and bicyclists. This is done by a combination of techniques, included among those listed below.
Lanes are reduced in width (from 12 feet to 11 or even 10 feet).
The number of lanes may be reduced, often from 4 to 3, which also improves safety for left turns and allows the most prudent driver to set the speed. This treatment is known as a road diet .
Sidewalks, if missing, are installed.
Curb cuts (driveways) may be consolidated to reduce walkway interruptions by moving vehicles.
Raised medians are installed, which improves safety for crossing pedestrians.
Universal design features are installed, including audible signals, curb ramps, and providing a 4-foot wide clear path of travel on the sidewalk, in accordance with the Americans with Disabilities Act.
Pedestrian crossings are enhanced with ladder-stye or zebra-style crosswalk markings, signal modifications such as a leading pedestrian interval or countdown timer , and as needed, flashing crosswalks -- lights embedded in the pavement that flash when activated by a crossing pedestrian.
Street parking is maintained or installed, which helps to discourage speeding.
Highway interchanges are modified to eliminate high-speed, free right turns. This is done by "squaring up" the interchange to resemble a typical 90-degree, signal-controlled intersection.
Corner treatments are installed. These may include curb extensions, right-turn slip lanes, or tighter turning radii, all of which slow right turns and provide greater visibility for pedestrians.
Transit accommodations are improved in a variety of ways.