Summary
You can use the Parking and Driveway to Street Connection Calculator (PDSCC) to determine the:
- Elevation that your parking area or garage floor can be placed at,
- Elevation of the Right-of-Way (ROW) at your driveway entrance.
Using this tool makes it easy for you to meet City Code requirements for driveways.
If you have questions or would like to talk to someone about how to use the calculator, we’re here to help!
Contact for help:
- SDCI help request form (https://sdci.zendesk.com/hc/en-us/requests/new?ticket_form_id=1500003356822)
- SDCI Zoning Reviewer assigned to your project
- SDOT Reviewer assigned to your project for arterial or complex street situations
Terms you will need to know
- alley – A public right-of-way not used for general travel that gives access to the rear of properties
- arterial – A high-volume street based on the Streets Illustrated Map
- curb – the raised edge to a street usually constructed of concrete
- driveway centerline – An imaginary line running down the middle of your driveway
- land survey – A document, prepared by a licensed land surveyor, that shows the existing features and elevations of your project area. It includes data about the street or alley you are connecting to
- parking area – The surface of your garage or outdoor parking
- right-of-way (ROW) – Public land for the use of the public
- right-of-way centerline – An imaginary line running down the middle of the right-of-way. This may or may not be at the center of the Street or Alley
- SDCI – Seattle Department of Construction and Inspections
- SDOT – Seattle Department of Transportation
- street – A public Right-of-Way used for the general moving vehicles and people and providing access to properties
- street type – How the City classifies a street based on the Streets Illustrated Map
- surface elevation – How high above sea level a point on the ground is – in this case as determined by a Land Surveyor
- zone category – A classification of land allowing and restricting types of development on parcels in the City of Seattle
Items you will need to get started
- Your project address
- The location where your new or modified driveway connects to a City street or alley
- Your new or modified parking area
- The surface elevation where your driveway centerline meets the right-of-way centerline
- The existing width of the right-of-way and the position of the street within it
- The Seattle Streets Illustrated Map (https://streetsillustrated.seattle.gov/map/)
- The zone category with the most coverage of the entire block of the street or alley your driveway connects (See: https://www.seattle.gov/sdci/resources/zoning-map-books)
- Microsoft Excel or other software compatible with the Microsoft .xlsx format
What you need to do
- Determine if your property qualifies to use the PDSCC. Most non-industrial zones outside of downtown and being accessed from a paved, non-arterial Street or Alley can use this calculator.
- Helpful Hints:
- If you think this calculator may not work for your project, contact your SDCI Assigned Zoning Reviewer.
- If your project requires a Street Improvement Permit (SIP) or SIP-Lite, work with your SDOT SIP Project Manager (SIP PM) to get the right information into the PDSCC based on your engineered plans.
- A paved Alley or Street is one that is surfaced with asphalt, concrete, or stone. An unpaved Alley or Street will be made of dirt, gravel, or other loose materials. The PDSCC only works when your driveway connects to a paved Alley or Street.
- The center of a Street is often at the center of the ROW, but not always. The PDSCC only works for Streets and Alleys centered in the ROW. You can check with your Land Surveyor or SDCI Assigned Zoning Reviewer to determine if this situation applies to you.
- Helpful Hints:
- Select and download the correct PDSCC worksheet for your project. This is determined by what your driveway connects to. There are three to choose from:
- Alley – Download the Alley version if your driveway connects to an alley
- Curbed Roadway – Download the Curbed Roadway version if your driveway connects to a Street that has an existing concrete curb
- Non-Curbed Roadway – Download the Non-Curbed Roadway version if your driveway connects to a Street that does not have an existing concrete curb
- Open the worksheet in Microsoft Excel or compatible software. You will be presented with blue and green boxes. Fill out all the light blue boxes with your project information. See “D – Input Fields”, below, for descriptions and instruction for each input box.
- Design your project using the output found in the light green boxes. City plan reviewers will use this information to check your design for issues. See “E – Output Fields”, below, for descriptions of the output information.
- If a red “ERROR” box appears it will direct you where you need to make any adjustment or fill in missing information.
- Save and export the worksheet to PDF. Include the worksheet with your plan set when submitting it to the City for review.
- Repeat the above steps for each driveway at your site.
Input Fields
All fields are required unless otherwise stated.
Driveway and Frontage Selections
Zone Category
Field Type: Drop-down list
Choose: The Land Use Zone Category with the most coverage of the entire block of the Street or Alley your driveway connects to
Reference: SDCI Zoning Map Books website (https://www.seattle.gov/sdci/resources/zoning-map-books)
Street Type (Does not apply to the Alley Calculator)
Field Type: Drop-down
Choose: The Street Type your driveway connects to
Reference: Seattle Streets Illustrated Map (https://streetsillustrated.seattle.gov/map/)
Urban Village P-Zone (Does not apply to the Alley Calculator)
Field Type: Yes/No drop-down list
Choose: Yes, if the street your driveway connects to is in a “P-Zone”, otherwise No
Reference: Seattle Streets Illustrated Map (https://streetsillustrated.seattle.gov/map/)
Within block of transit stop on RapidRide (Does not apply to the Alley Calculator)
Field Type: Yes/No drop-down list
Choose: Yes, if your driveway is within a block of a transit stop on the King County Metro RapidRide system, otherwise No
Reference: King County Metro Maps (https://kingcounty.gov/en/dept/metro/routes-and-service/schedules-and-maps)
Project Information
SDCI Permit No
Field Type: Text box
Enter: The construction permit number assigned to you by SDCI
Street Address
Field Type: Text box
Enter: The address on your construction permit application
Driveway Identification
Field Type: Text box
Enter: A description of the driveway, for use when your project has more than one driveway
Date Prepared
Field Type: Text box
Enter: The date you used the calculator
Driveway Diagram
Distance “L”
Field Type: Number Value
Enter: The length of your driveway, in feet, that will be on your private property before any setbacks, easements, or dedications required by the City. You can get this distance from your site designer.
Distance “P”
Field Type: Number Value
Enter: The distance from the Right-of-Way centerline to the existing property line before any setbacks required by the City. You can get this distance from your Land Surveyor.
Elevation “C”
Field Type: Number Value
Enter: The surveyed elevation at the center of the existing Right-of-Way. You can get this elevation from your Land Surveyor.
Output Fields
Your site plan will need to reflect all the output fields to ensure it meets City requirements.
Required Setback “F”
The width, in feet, of the setback, easement, or dedication the City requires along your property based on the Seattle Municipal Code.
Elevation “R”
The elevation, in feet, where your driveway centerline will cross the Property Line or any setbacks required by the City.
Max Slope “S”
The maximum slope, in percent, allowed for your driveway. Vertical curves to smoothly transition between slopes are required by the Seattle Municipal Code.
Max Elevation “EMAX”
The maximum finished elevation, in feet, of your outdoor parking area or garage. It is recommended to set your finished elevation below, not at, the Max Elevation.
Min Elevation “EMIN”
The minimum finished elevation, in feet, of your outdoor parking area or garage. It is recommended to set your finished elevation above, not at, the Min Elevation.