P Street Corridor, Phase 1

Challenge

Project Goals

• Transform previously unpleasant, underused spaces and provide enhanced public access
• Enhance the environmental integrity of the corridor by capturing 100% of stormwater runoff on-site, improving street tree health and increasing canopy coverage, and by planting 100% native and non-invasive species
• Improve cultural identity of the corridor through engagement of local artists and cultural entities
• Improve economic performance of businesses and properties along the corridor by increasing the total assessed value of the corridor’s properties and lowering vacancy rates
• Increase outdoor seating space and the number of bike racks
• Improve public perception of P Street to over 50% of users rating it as “Very Good” as compared to a pre-construction survey

• 45 shade trees including honey locust (Gleditsia triacanthos) and Valley Forge American elm (Ulmus Americana ‘Valley Forge’) were planted in a modular suspended pavement system which provides an average of 1,000 cu ft of soil per tree. Tree canopy coverage was increased from 7.6% to 30%. 
• Suspended decking units provide a change in pavement materiality, indicating a change in use from walkways to small patio spaces preserving 7 existing large-caliper trees. 
• 27% of the corridor’s surface is permeable due to the incorporation of additional planting areas and permeable pavers. 8.2% was permeable pre-construction.
• 16 stormwater cells along the corridor have the capacity to manage 90% of rain events. They were planted with 100% native plant species that attract beneficial insects and reduce water demand for irrigation, including prairie dropseed (Sporobolus heterolepis) and butterfly milkweed (Asclepias tuberosa).
• Crosswalk distance was decreased by an average of 27 ft using curb extensions and smaller turning radii.
• Vehicular lane widths were reduced from 15 ft to 11 ft to encourage a decrease in travel speeds.
• Available bike parking was increased by 40% with new bike racks.
• Pedestrian seating options were more than doubled through the addition of limestone benches and metal cafe tables and chairs.
• A 57-ft colored glass tower designed by regional artist Jun Kaneko stands along the corridor. 
• In the evening, the streetscape showcases a variety of lighting features such as blue LED light strips beneath benches, LED banners, and hanging tree lanterns.

The estimated cost for the materials and installation of a single immature 2” caliper street tree with a modular suspended pavement system is approximately $5,725, while traditional installation of the same tree is estimated to cost approximately $350. However, the appraised value for a mature street tree in good soil conditions like those provided by a modular suspended pavement system is approximately 27.4 times higher than at initial planting (from $350 initial to $9,590 mature) as compared to an increase in value of only 1.5 times for a conventionally planted street tree (from $350 initial to $525 mature).

• Contractor selection was the responsibility of the City of Lincoln, a government entity obligated to select the lowest-bidding contractor. As a result, the selected contractor had minimal experience installing highly-designed and complex landscapes. Although the City benefited financially from a lower-cost bid, the installation of the design was not as refined as the designers and the City anticipated. The City had not realized the level of experience needed by the contractor for a project of this caliber, and the bid documents included only minimum qualifications. Post-project, the City of Lincoln expressed a desire to include higher standards in contractor selection on future projects and is looking forward to implementing similar street revitalization projects nearby with newly gained experience in contractor selection.
• With the primary design firm located remotely, a local firm was hired as a subconsultant for construction documentation and observation in order to reduce travel expenses. Although video conferencing and occasional visits helped make it a smooth process, issues arose when drawings needed to be stamped, resulting in the local firm becoming the architect of record. Although clearer communication between the firms may have avoided this issue, this scenario illustrates the tradeoff between travel expenses and technical and communication-related mishaps.
• The project’s public engagement forums and polls were well-attended and ultimately successful. Aiming to be as transparent as possible, the primary design firm provided a full range of options to the public without the design team preselecting options they thought were best. From these forums, the public was able to prioritize where to allocate the budget, which was set by a downtown tax increment financing (TIF) fund. A large part of the success of the public process can also be credited to the transportation engineer who built strong relationships with City of Lincoln staff. This sense of rapport encouraged the public to participate more than they likely would have otherwise.
• When considering the project’s planting strategies, the designers tested the urban soil conditions in Lincoln and found that the soil does not percolate well. To increase percolation for healthy tree and plant growth, the designers recommended the use of rain gardens. However, instead of rain gardens, the City requested shallow stormwater cells similar to those on adjacent streets. Because bioswales incorporate considerably less amended soil than rain gardens, this resulted in lower levels of percolation and less stormwater capture as compared to the proposed rain gardens.

Modular suspended pavement system: DeepRoot Silva Cells
LED lighting strips: Plexineon (iLight Technologies)
Pedestrian light fixtures: Louis Poulsen
Light poles: Valmont Industries 
Hanging tree lanterns: Architectural Area Lighting
LED banners: Stantec
Limestone slab benches: Limestone sourced locally from Nebraska
Permeable Pavers: Pavestone sourced from Kansas City, MO

Project Team

Client: City of Lincoln
Landscape Architecture and Planning: Design Workshop, Inc.
Landscape Architecture, Coordination, and Construction Administration: The Clark Enersen Partners
Retail and Development Strategy: Urban Strategies Real Estate Advisors
Transportation Planning: LSC Transportation Consultants
Survey and Civil and Electrical Engineering: Olsson Associates
Environmental Graphics: Stantec
Architectural Lighting Design: PBQA
Artist: Jun Kaneko Studio

Role of the Landscape Architect

The landscape architectural design of the project was divided among two firms – the primary design firm and a local firm. The responsibilities of the primary design firm were the creation of the master plan, coordination of public engagement, and leadership of design development. The local subconsultant firm’s responsibilities centered on the development of construction documents and details, implementation of the design, and construction administration.