Denver firm studioINSITE led a $14 million transformation of the Mile High City's 14th Street, a dozen blocks of downtown corridor from Colfax Avenue to Market Street that the city considers its "ambassador" to new arrivals. Stone pavers (Lyons red sandstone, black and red granite), modern 21-watt LED luminaires (???Olivio Candelabra' on ???Rotterdam' poles, both from Selux) and six LED illuminated wayfinding kiosks on granite bases are just the introduction to the transformed streetscape.
Photos: Williamson Images/studioINSITE, LLC

Denver's largest streetscape project in over three decades presented a "once in a generation" opportunity to revitalize and rebrand 14th Street, a major downtown avenue. The design, led by a partnership between indigenous landscape architecture firm studioINSITE and city and county agencies, established a new cultural core for the downtown area, welcoming visitors from around the world to the Mile High City. Twelve blocks of vehicle-dominated street were transformed into a flexible, pedestrian-oriented, Greenroads-certified multimodal transit corridor that virtually every person arriving ??" whether by car, bus, light-rail, bicycle, or on foot ??" meets as their "ambassador" to downtown Denver.

Program/Scale/Budget
Before starting the design work, studioINSITE sent staff members to visit selected cities across the country and abroad to study firsthand how streetscape precedents could relate to 14th Street. They returned with the inspiration to transform a forgotten corridor into one of this nation's great streets and evidence to demonstrate lessons learned from around the globe.

As the lead designer and public face of this extraordinary project, studioINSITE facilitated a highly collaborative and extensive seven-year design and construction process with the offices of the mayor and city council, public works agencies, the Downtown Denver Partnership, 14th Street property owners, and a multidisciplinary project team. The landscape architecture team, led by Dennis Rubba, ASLA, coordinated all public meetings, collected feedback from hundreds of stakeholders, designed and detailed all hardscape and softscape features, and assumed design oversight for all roadway, lighting, and wayfinding components.

14th Street encompasses 12 city blocks. There was no single programmatic solution for the entire length of the streetscape project, and no equitable funding assessment model for property owner contribution, so these had to be developed.

The city's first "General Improvements District" resulted in the street being divided into "Premium Zone" and "Standard Zone" sections to address budgetary, future block redevelopment, construction and maintenance priorities, all the while maintaining the look and feel of a complete and contiguous project.

Wayfinding Designs
14th Street lies at the convergence of two historic city grids, and is the first street encountered by motorists entering downtown. It is traversed on foot by thousands of people. The project branded 14th Street as the "Ambassador," orienting people to downtown destinations along a new streetscape known as the "Red Carpet." A creative signage system has become a new feature in itself, including 30-foot tall, three-sided gateway monuments, custom kiosks and banners combined with accent lighting, unique street furnishings, well detailed paving and seasonal landscape colors and textures that change block-by-block.

The landscape architects developed two levels of streetscape design??""standard" and "premium" zones, whose amenities varied according to maintenance, budget and future redevelopment concerns.

A New Urban Forest
The promotion of a healthy landscape within this dense urban environment was a significant design challenge. studioINSITE worked directly with the city's Forestry and Parks & Recreation departments to establish a new paradigm for urban forestry. This included a plant diversification strategy based on species adaptability to each block's specific microclimate. It also included the development of a revolutionary inground planter design, which combines a series of 35'x8'x5' below-grade root zones with porous paving, predicted to significantly increase the lifespan and growth capacity for street trees in urban environments. 14th Street is now one of the country's most sustainable streets.

Denver is a challenging environment in which to promote a healthy, thriving landscape. Species diversity was one of the primary goals of the tree planting design, which was also crafted in close coordination with Denver's Forestry and Parks & Recreation Departments.

Three varieties of elms were specified (Triumph, Regal, and Central Park Splendor). The Espresso variety of Kentuckycoffeetree (a recent seedless cultivar), Princeton Sentry ginkgos, Turkish filberts, Schumard oak, and State Street Maples were newer varieties of trees added in response to the street's microclimates.

studioINSITE also suggested denser spacing of trees due to the expanded root zone areas designed for the street. On 14th Street, trees are spaced as close as 20 feet on center rather than the previous 35-foot spacing, establishing a more inviting pedestrian experience and reducing the urban heat island effect. The city now celebrates 14th Street as Denver's new urban park.

The grating system and amended topsoils were designed by the landscape architect and installed to accommodate continuous tree root zones below the permeable unit pavers, promoting healthy and thriving urban trees for future generations.

Paving Challenges
The design required extraordinary research, testing, and selection of hardscape paving materials. Sand-set permeable pavers were installed over the new grating, which is suspended over the plantings and finished with a custom tree ring collar and electrical bracket. Conventional installation details had to be modified to withstand Denver's harsh freeze-thaw cycles, while accommodating flexible outdoor functional uses and providing ADA accessibility.

The design produced a new, state-of-the-art suspended paver grating system, promoting sustainable practices and assuring a thriving urban landscape for generations to come.

The monumental scale of the existing utility infrastructure ??" some parts more than a century old ??" had to be carefully integrated, block-by-block, into the design, despite major space challenges, code restrictions, and budget constraints. The streetscape design had to be adapted to each unique block, each undetected utility and every individual property's condition.

During construction, sand-set permeable pavers were installed over a custom, state-of-the-art suspended grating system with a custom tree ring collar and electrical bracket. The landscape architect worked directly with Denver's city forester to improve on traditional urban forestry practices, leading to a revolutionary in-ground planter and plant diversification specific to each block's microclimate.

Sustainability
14th Street has become a "must-see" destination and a high watermark in the evolution of the city's downtown environmental, social, and economic achievements.

The design incorporates extensive infrastructure development, site construction materials, and water conservation efforts that have established 14th Street as the first streetscape in the United States to receive "Greenroads" certification. The effort to achieve such recognition is unprecedented in contemporary streetscape design, and required a significant amount of coordination between the design, management, and construction teams.

Twelve 30-foot-tall pillars, fabricated by DaVinci Sign Systems of Denver, light up the night at the northeast corner of each of the intersections along the 12-block stretch. Denver-based ArtHouse Design developed the banner and "badge" identify for the 14th Street elements, and was responsible for the design and fabrication specs for the pillars. The structures are primarily aluminum with steel center columns, granite bases and internally illuminated acrylic faces. Phillips ???ColorBlast' LEDs offer myriad color options. The pillars also have an LED strip along one edge that can be changed out for different occasions. The pillars have large, lighted street names facing traffic, and a map on the pedestrian side highlighting area attractions. There are also vertical art elements. The 12 pillars cost $320,000.

"Place-Making"
Within the redeveloped 12-block corridor are the Denver Convention Center; a principal municipal building; the city's largest hotel, and the world-class Center for Performing and Cultural Arts Complex; the University of Colorado at Denver; the historic Larimer Square retail center; upscale boutique hotels; numerous local businesses, commercial offices, and nearly 3,000 residential units. The transformative design work on 14th Street has made it Denver's "beachfront property," attracting over $1.5 billion in public and private investments.

With a total construction budget of $14 million and fighting the public's misperception that this was a "roadway improvement" project, studioINSITE constantly championed the virtues of expanded sidewalk widths, quality pedestrian lighting and signage, use of cost-conscious materials, effective maintenance practices, an expanded urban forest, and sustainable practices. The corridor has been honored with the highest awards from ASLA Colorado, Downtown Denver Partnership, American Public Works Association's "Project of the Year," Greenroads Foundation, and the Women in Transportation "Big Project of the Year."

Custom granite benches are etched with the "14" Street designator. The custom colored linear concrete unit pavers are set on sand to infiltrate stormwater into the tree vaults

Bike Friendly, Too
Denver B-cycle was the first large-scale municipal bike sharing system in the U.S. The city boasts 80-miles of multiuse trails, 96 miles of bike lanes, 41 miles of "sharrows" and 400 miles of signed bike routes. In that spirit, 14th Street added a dedicated bike lane that connects Cherry Creek trail and Civic Center Park, and new bike racks (Madrax).

The successful achievement of all the project's goals is unprecedented in Denver's history of streetscape design. The improvements have transformed 14th Street into Denver's destination "Ambassador Street," welcoming visitors to the downtown area with an enhanced pedestrian experience, improved livability, and new opportunities for economic vitality.

The project elevates the urban fabric of downtown Denver to a national scale, raises the investment in the public realm to new heights, and establishes higher expectations for anticipated streetscape and landscape architectural projects.

Team List
Lead Designer: studioINSITE, LLC
Landscape Architect of Record/Firm: Dennis W. Rubba, ASLA / studioINSITE, LLC
Client/Owner: City & County of Denver and Downtown Denver Partnership

Consultants:
Admin./Roadway Engineering: PB World (Parsons Brinckerhoff)
District Formation: CRL Associates, Inc.
Irrigation Design: HydroSystems-KDI, Inc.
Lighting Design: Clanton & Associates, Inc.
Utility Location: Goodbee & Associates
Wayfinding & Signage: ArtHouse Design

Contractors:
General Contractor: Concrete Works of Colorado
Electrical/Lighting: WL Contractors
Kiosks/Monuments: DaVinci Signs
Landscape/Irrigation: Guild and Associates
Sealing, Concrete Sawing: Reliable
Stone Work, Unit Pavers: Colorado Custom Rock

Raised granite planter curbs, custom planter pots, accenting lights, saw-cut paving with sandblasted accents, colorful xeric (low water use) landscaping, and a suspended paver grate system have transformed the street into the first large-scale "Greenroads" certified street in the country, as well as one of the Denver's most thriving and vibrant corridors.

Hardscape:
Concrete Unit Pavers: Bogert Products
Concrete Sidewalk/Street Pavement: Aggregate Industries
Granite Pavers, Benches: Cold Springs Granite Company
Paver Grate Units: Ironsmith
Truncated Dome Detectable Warning Pavers: Stonebilt

Irrigation: CPS Distributors

Lighting:
In-Grade Lights (mfr.): Lightwild
Local Electrical Supplier/Dist.: Rexal
Pedestrian Lights (mfr.): Selux

Site Furniture:
Bike Racks (mfr.): Madrax
Planter Pots (mfr.): Escofet 1886, S.A. (Spain)

Plants: Branch Out Partners, LCC

Topsoil (Amended): Colorado Materials

Selux pole lighting highlights the finished look of the pavers and tree ring collar over the suspended grating system. The hardscape installation necessitated the development of new material mix specifications and technical details to withstand Denver's harsh freeze-thaw cycles, accommodate flexible outdoor functional uses, and promote sustainable practices and ADA accessibility.