A USDOT University Transportation Center

Curb Elimination

Curb and gutter elimination is a form of stormwater management that allows runoff to be redirected to pervious areas where it can be filtered.1,2 Although curbs and gutters can efficiently move excess water into the storm drain system, this design does not allow for pollutant removal or efficient filtration through porous structures. Therefore, future designs should consider replacing curbs and gutters with solutions such as curb cuts and green infrastructure. Curb cuts are where portions of the curb have been cut out and modified to allow for the passage of water from the street to an inlet before it enters the storm sewer.3 It can be thought of as a water bypass system where excess runoff is collected and directed to more permeable surfaces. Green infrastructure alternatives to curbs and gutters include swales, bioretention systems, or permeable pavement.4 Grassed or vegetative swales is a common stormwater practice that collects and infiltrates the runoff from roadways.5 Swales are similar to shallow ditches on either side of the roadway and are especially appropriate in low- to medium-density development areas.

Considering this strategy will help achieve the goal of the following objectives

  • Less Contamination
  • Less Emissions
  • Less Traffic Noise
  • Connectivity and Inclusion
  • Healthy Destinations
  • Less Traffic Violence
  • Active Transportation
  • Green Space

Transportation lifecycle phases

This strategy is associated with the following transportation lifecycle phases:

  • Construction
  • End of Life
  • Maintenance
  • Material Selection
  • Operations
  • Policy and Planning
  • Project Development

Who's involved

  • Drainage engineers
  • MPOs
  • Private developers
  • Transit agencies

Curb and gutter elimination is a form of stormwater management that allows runoff to be redirected to pervious areas where it can be filtered.1,2 Although curbs and gutters can efficiently move excess water into the storm drain system, this design does not allow for pollutant removal or efficient filtration through porous structures. Therefore, future designs should consider replacing curbs and gutters with solutions such as curb cuts and green infrastructure.

Curb cuts are where portions of the curb have been cut out and modified to allow for the passage of water from the street to an inlet before it enters the storm sewer.3 It can be thought of as a water bypass system where excess runoff is collected and directed to more permeable surfaces.

Green infrastructure alternatives to curbs and gutters include swales, bioretention systems, or permeable pavement.4 Grassed or vegetative swales is a common stormwater practice that collects and infiltrates the runoff from roadways.5 Swales are similar to shallow ditches on either side of the roadway and are especially appropriate in low- to medium-density development areas.

How it Helps

The elimination of curbs and gutters and establishing curb cuts or green infrastructure alternatives allows rainwater filtration, pollutant removal, and can even aid in curb appeal. These solutions are examples of low impact development (LID) practices that protect water quality and aquatic habitats by mimicking or preserving natural stormwater drainage processes.6,7 This approach focuses on recreating natural landscape features and minimizing impervious structures. By emphasizing infiltration, LID can reduce runoff, minimize flooding risk, reduce groundwater pollution, mitigate the urban heat island effect, and improve neighborhood aesthetics.

Implementing

Traffic or Safety Hazards:

Before curb removal, the surrounding traffic environment should be analyzed to ensure that the curb elimination will not result in any traffic or safety hazards. Curbs may be necessary for traffic control in particular areas and, therefore, other solutions should be considered.8 However, curb cuts and the partial elimination of curbs may result in other safety concerns for various road users.

Maintenance:

Curb alternatives, such as curb cuts and swales, must be continuously maintained and removed of debris to prevent water blockage. Grassed and vegetation swales should be regularly mowed and not treated with fertilized, pesticides, and other chemicals to prevent contamination.

Examples

1) Seattle’s Street Edge Alternatives Project

In 2001, Seattle completed their Street Edge Alternatives Project (SEA Streets) that focused on implementing drainage designs that mimicked the natural landscape. These efforts focused on reducing impervious surfaces, building swales, and adding vegetation. Together, these efforts were able to significantly reduce the volume of stormwater and runoff leaving the street.

https://www.seattle.gov/utilities/neighborhood-projects/street-edge-alternatives

1. EPA. (2023). Stormwater Management Practices at EPA Facilities. https://www.epa.gov/greeningepa/stormwater-management-practices-epa-facilities#Seven
2. Richland Soil and Water Conservation District. EPA Best Practices: Environmental Protection Agency (EPA) Stormwater Management Preferred Practices. https://richlandswcd.net/stormwater-drainage/epa-best-practices/
3. Marritz, L. (2013). The Rise of the Curb Cut Part 2: Don't Be Afraid of the Water. Deeproot. https://www.deeproot.com/blog/blog-entries/the-rise-of-the-curb-cut-part-two/
4. EPA. (2021). Stormwater Best Management Practices: Eliminating Curb Cuts and Gutters. https://www.epa.gov/system/files/documents/2021-11/bmp-eliminating-curbs-and-gutters.pdf
5. City of Naples Streets and Stormwater Department. Save the Swales. https://www.naplesgov.com/sites/default/files/fileattachments/streets_amp_stormwater/page/3191/saveourswales_1.pdf
6. EPA. (2022). Urban Runoff: Low Impact Development. https://www.epa.gov/nps/urban-runoff-low-impact-development
7. EPA. (2015). Benefits of Low Impact Development: How LID Can Protect Your Community's Resources. https://www.epa.gov/sites/default/files/2015-09/documents/bbfs1benefits.pdf
8. Maestri, B., et al. Managing Pollution from Highway Storm Water Runoff. Transportation Research Record 1166. https://onlinepubs.trb.org/Onlinepubs/trr/1988/1166/1166-003.pdf