Global Street Design Guide

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Table of Contents

Global Street Design Guide

Case Study: 21st Street; Paso Robles, USA

Location: Paso Robles, California, USA
Population: 30,000
Length: 640 m–5 blocks
Right-of-way: 24 m
Context: Residential and Commercial Main Street
Cost: 2.5 million USD
Funding: City of Paso Robles and Urban Greening Grant from the California Strategic Growth Council


This is a commercial corridor and one of four railroad crossings in north Paso Robles, California. It provides a key connection between a local school and a city park, and access to the California Mid-State fairgrounds. When the city was developed in the 1880s, the street was paved over buried Mountain Springs Creek, a tributary of the nearby Salinas River that drains 1,200 acres, and few infrastructure provisions were made for the creek. As the city grew and upstream development accelerated, polluted stormwater runoff increased. Before the transformation, large storms flooded the street and adjacent properties, causing
erosion and creating traffic hazards.

Early in the design process, team members recognized the overlapping benefits of designing for safety, environmental sustainability, and high-quality public spaces. The newly reconfigured corridor transformed five city blocks by calming traffic, improving cycle and pedestrian mobility, and introducing a natural drainage into the transportation network, increasing groundwater recharge.



  • Reduce the frequency and severity of street flooding and increase stormwater infiltration.
  • Improve pedestrian and cyclist safety.
  • Reduce traffic speeds by incorporating traffic calming devices.
  • Increase shade and aesthetic appeal by planting trees and drought-tolerant plants.

Lessons Learned

After being fined for an illicit discharge to the Salinas River, the city worked with the state water board to redirect the fine to fund the concept plan, which was the basis for an application for a State
Urban Greening Grant that funded final engineering and construction.

Working with a mix of public, private, and non-governmental organizations allowed for broader support and access to innovative funding while creating strong and diverse project advocates.

Keys to Success

Leverage professionals with experience in emerging green street technologies to support the expertise of local engineers.

Design elements along the corridor respond to the right-of-way constraints as well as the stormwater and mobility goals.


Public agencies
City of Paso Robles (owner) California Central Coast Water Board

Private Group and Partnerships
California Central Coast Low Impact Development Initiative

Citizen Associations and Unions
Stakeholder Advisory Group (adjacent property and business owners)

Designers and Engineers
SvR Design Company, CannonCorp Engineering, Earth Systems Pacific


Key Elements

Stormwater management, including green infrastructure, is provided.

Widened sidewalks to provide a 2 m-minimum clear path.

On-street cycle lanes are provided.

Traffic calming elements include curb extensions, pedestrian crossing striping, in-pavement lighting, and signage.

Project Timeline

Adapted by Global Street Design Guide published by Island Press.