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" 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
| 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. Buildings are based on the 2D lidar-derived building footprints, a deliverable of the 2023 state flight. |
| Driveway | Paved surface from edge of curb to structure. In cases where sidewalk is overlapping, sidewalk takes priority. Greater than 8 feet wide and 10 feet long. |
| Parking | Paved surface with visible parking lanes. Greater than 500 square feet. |
| 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 | Railway infrastructure visible from source imagery. |
| 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. |
| Sports Field Paved (paved sport ground) | Any paved recreational area such as tennis courts and running tracks. |
| Sports Field Unpaved (unpaved sports ground) | Any unpaved recreational area such as baseball grounds and soccer fields. |
| Swimming pool (in-ground) | 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. |
Impervious “Road” Layer Classes
| CLASS | DESCRIPTION |
| Road | Edge of curb, greater than 8 feet wide. |
| Sidewalk | Paved path for pedestrians, typically running parallel to the street. Sidewalks can be within the public right of way where private sidewalks often connect driveways to building entrances. Sidewalks take priority over driveway or other features. |
| Crosswalks | A marked part of road indicating where pedestrians have the right of way to cross. Crosswalks intersect with roadways and sidewalks. |
| Continental crosswalk | Crosswalks marked with thick, horizontal stripes that extend across the road. |
| Ladder crosswalk | Crosswalks that combine the parallel lines with horizontal stripes between them. |
| Mid- block crosswalk | Crosswalk at a mid-block location rather than at an intersection. |
| Other crosswalk | Any type of crosswalk markings that do not fit the above categories. |
| Standard crosswalk | Traditional crosswalks marked by two parallel lines. |
Impervious “Lane” Layer Classes
| CLASS | DESCRIPTION |
| Turning 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 turn lane | Left turn lanes are positioned on the far left side or center of the road, separated from the through lates. Visible left-turns arrows are typically painted on the lane to indicate the intended movement. The lane is usually located near intersections, medians, or an oncoming lane, guiding vehicles to make a left turn. Often isolated by solid or dashed lines. indicating it is not for straight traffic but for turning left. |
| Right turn lane | Right turn lanes have visible right-turn arrows painted on the lane indicating the intended movement. The lane is typically located near intersections, guiding traffic toward a right turn and positioned on the far right of the roadway, separated from through lanes by solid or dashed line. |
| Through Lane |
Through lanes are lanes that run uninterrupted along the roadway without diversion into turning or exit lanes. They are generally centrally positioned on the roadway, away form edges where turning lates might appear. Solid or dashed lines mark the lane, showing a continuous path forward. |
| Left Through Lane | |
| Right Through Lane | |
| Bike Lane | Bike lanes as visible on aerial imagery. Sharrows (bike and vehicle lanes) are in the Through Lane category. |
| Left right lane | Lane designated for both left and right turns, greater than 8 ft wide. |
| Shoulder | Shoulders are located on the far edges of the road, outside the through lanes. They typically have a wider strip of pavement or gravel with no active traffic, used for emergency stops or breakdowns. They are delineated by solid boundary lines, often a white or yellow line separating the shoulder from the travel lanes. Shoulders do not connect directly to intersections or exists, serving as a buffer rather than a traffic lane. |
| Slip turn lane | Dedicated turning lane allowing vehicles to merge into cross-street traffic without stopping, greater than 8ft wide. |