The impervious surfaces are surfaces that allow little or no water infiltration. Three impervious surface layers were created from 2023 aerial imagery.
Impervious Surface "Land" Polygon Layer. The land choice for each block includes all of the impervious surface polygons. Each polygon belongs to one of the following classes: bridge, building, driveway, parking, paved sport ground, pavement, railway, road, sidewalk, swimming pool, and unpaved sports ground. See below for class definitions and more information.
"Road Centerline" Line Layer. The road centerline choice for each block includes the roads as single line feature along with related line features. Each line segment includes a width measurement and belongs to one of the following classes: road, sidewalk, crosswalk, ladder crosswalk, mid- block crosswalk, other crosswalk, or standard crosswalk. See below for class definitions.
"Lane" Line Layer. The lane layer includes multiple lines for each road that represent traffic. Each line segment includes a width measurement and belongs to one of the following classes: through lane, shoulder, right through lane, right turn lane, left through lane, left turn lane, left right lane, bike lane centerline, slip turn lane.
Download
Click on a block on the map to open a pop-up which contains options for downloading the impervious layers.
Service
The service of the impervious surface polygons will be be available on the CT Geodata Portal and will include the service link.
Impervious Surface “Land” Layer Classes
Definitions coming soon!
| CLASS | DEFINITION |
| Bridge | Driving surfaces that are elevated from terrain level. Does not include walking paths. Bridges are greater than 8 feet wide and 50 feet long. |
| Building | The geometric footprint of each building greater than 100 square feet. Buildings are derived from the roofline and the wall facade to correctly interpret where a structures foundation meets the ground. |
| Driveway | Paved surface from edge of curb to structure. In cases where sidewalk is overlapping, sidewalk takes priority. |
| Parking | Paved surface with visible parking lanes. |
| Paved sport ground | Any paved recreational area such as tennis courts and running tracks. |
| Pavement | Any paved surface that does not fall into the specific impervious feature classifications. As with other features, must be greater than 100 square feet. |
| Railway | |
| Road | Edge of roadway, including curbs. In the case where roads overlap or where they are elevated from the ground, the elevated/overlapping surface(s) are classified as bridges, and the terrain surface is classified as road. Roads are greater than 8 feet wide and 50 feet long. |
| Sidewalk | A paved path for pedestrians, typically running parallel to a street. Private sidewalks include sidewalks outside the right of way of public property, for example, a sidewalk that leads from the edge of a driveway up to the front door of a house. Public sidewalks are defined as those that typically reside within the public right of way, parallel to a street. Sidewalks take priority to driveway, or other paved surface, in the landcover feature classifications. Sidewalks are greater than 3 feet wide and 10 feet long. |
| Swimming pool | Sub-surface open water on residential or commercial property that is clearly not a natural body of water. Swimming pools must be greater than 100 square feet. |
| Unpaved sports ground | Any unpaved recreational area such as baseball grounds and soccer fields. |
Impervious “Road Centerline” Layer Classes
Definitions coming soon!
| CLASS | DESCRIPTION |
| Continential crosswalk | |
| Ladder crosswalk | |
| Mid- block crosswalk | |
| Other crosswalk | |
| Road | |
| Sidewalk | |
| Standard crosswalk | |
Impervious “Lane” Layer Classes
| CLASS | DESCRIPTION |
| Bike lane centerline | Bike lanes are extracted based on visual interpretation of the aerial imagery. Only lanes specified for bikes shall be classified as a unique category, sharrows (bike and vehicle lanes) are maintained as through lane traffic. |
| Left turn lane Right turn lane |
A Turning Lane is a lane placed between opposing lanes of traffic for the purpose of allowing traffic from either direction to make left turns off a roadway. Each identified feature shall have a width measurement on a mean basis for each segment. Greater than 8 feet wide. |
| Left right lane | |
| Left through lane Right through lane Through lane |
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| Shoulder | A shoulder, hard shoulder, or breakdown lane is an emergency stopping lane by the verge of a road or motorway, on the right side in countries which drive on the right. |
| Slip turn lane |