A New Design for Arlington Sidewalks?
Look out, Arlington! A new sidewalk design has made its debut on North Court House Road between 14th and 15th Streets. And if it passes the test, you may see a lot more of it in our commercial corridors in the future.
Pre-cast concrete unit pavers have been Arlington's standard sidewalk material for commercial areas for over 25 years. The familiar octagonal and interlocking rectangular pavers are found throughout the Rosslyn-Ballston corridor. They've also been used in some crosswalks for a number of years. Over time however, some of these pavers have started to show their limitations. These are: warping (uneven settling), texture, cost and aesthetics.
Most pavers are installed on a sand base, allowing for freeze-thaw expansion. Over time, uneven settling leaves warped walking surfaces that pose a tripping hazard. Also, standard 8-inch 
pavers have beveled edges that create jarring vibrations for wheelchairs, baby strollers and shopping carts - even on otherwise level walkways. Lastly, in calculations for crosswalks, pavers were found to be at least twice as expensive to install and maintain as concrete. 
Concrete sidewalks are expected to have a much longer lifecycle than pavers. Added to these functional issues, are aesthetic ones: the subtle, earth-toned "Burnie Blend" pavers that were once considered special have become commonplace - even dated, like some of the 1970s architecture of their surroundings.
Recently WALKArlington staff was asked to look at alternatives to sidewalk pavers, with the goal of creating a durable, safe, cost effective and 
attractive walking environment. Interestingly, a study of different paving materials pointed to poured-in-place concrete sidewalks as the material of choice. Using special additives and surface treatments, standard concrete can be made to resemble many other high-quality materials, while still retaining concrete's fundamental strengths.
Staff and citizen advisors cautioned that the community's emotional and financial investment in concrete pavers might be an impediment to change: For some, its reseblance to brick has positive connotations. Transportation Planning design staff was convinced though, that concrete had enough inherent design potential to propose it as the new standard - only with a twist!
Interestingly, strong opposition never developed. In fact, some of staff's public presentations were met with applause when explaining the change from the paver standard. This might be attributed to a fundamental change in the way Arlingtonians have begun to think about public space.
Thirty years ago, Arlington's metro corridors were designed under the premise that pedestrians should not be on the same streets as cars and should do their shopping in indoor "centers." What ground level stores there were were often located in oddly shaped plazas or hidden behind tinted glass with bland, uniform signage. In that setting, stores were seen as an anonymous backdrop to the decorative sidewalks, plazas and street furniture. 
The Rosslyn and Ballston metro plazas and their skywalks are examples of this thinking. This arrangement however, never managed to generate the lively pedestrian activity once anticipated. The new model of public space reverses that relationship. We now focus on the design of storefronts and facades, the arrangement of entries and windows and the careful location of loading and service areas. The sidewalk is a functional and consistent backdrop to all of this and not a goal unto itself. Two successful recent examples of the of this model are Market Commons in Clarendon and Pentagon Row.
To that end, WALKArlington is working with local concrete contractors to design a poured-in-place concrete slab that incorporates texture, color and pattern with tactile and visual appeal, yet is simple to construct and maintain. The new design relies on the simple combination of "field and border." 
The field is a directional slate pattern imprinted onto standard concrete, using commercially available rubber mats and a dark gray tinted release agent to enhance the subtle surface texture of the slate. The border is troweled smooth. Control joints are saw-cut to give a sharp, clean look. A clear, sprayed on sealer adds silica grit for improved wet friction and helps ensure durability.
This design will be a "base model" sidewalk that will serve as a flexible framework allowing for field adaptations and design variations. 
Though this first installation was built along the back of the curb, most new sidewalks in Arlington will have street trees and space for decorative treatments between it and the curb. It's neutral look and adaptability means it can be integrated with other, more decorative treatments at special locations, such as in front of important building entries, at the termination of vistas and around civic sites. This sidewalk creates a practical and tasteful backdrop that allows these distinctive places to stand out and be recognized.
- submitted by WALKArlington Urban Designer David Goodman, AICP. 703.228.3709; dgoodman@arlingtonva.us.
