Use this lab to compare scenarios and ask better questions about NC-12. Its exposure screen is preliminary and has not been validated against observed road flooding.
MODEL STATUS Exploratory / educational · not calibrated
Real geography, with a date attached
The roadway comes from NCDOT’s state-maintained centerlines, retrieved November 4, 2026. The route includes the Jug Handle Bridge; the former S-Curves are not shown as present-day NC-12. This snapshot may predate very recent repairs or realignments.
Elevation samples use the USGS 3D Elevation Program via EPQS. Detailed 3D focus tiles, where available, use the USGS 3DEP elevation image service and USGS imagery. Sample metadata identify acquisition vintages of 1996 and 2003. These legacy elevations do not represent current dunes, recent beach nourishment, storm damage, or repairs. The focus tiles use the same legacy national elevation collection; image and elevation acquisition dates can differ. This age is a major limitation for present-day flood prediction. The display grid is resampled and does not imply that source data are equally detailed. NAVD88 is the typical CONUS reference; a local datum reconciliation has not been performed.
How the road colors work
At each sampled surface-road section, screened depth = max(0, greater of ocean and sound level − sampled ground elevation). This assumes water can reach the road. Alongshore hydrodynamics, duration-dependent filling, barriers and culverts are not solved. A road below the chosen water level may remain dry behind an intact dune. Conversely, waves or drainage can flood a road that this screen leaves dry.
Colors show depth categories, not a probability of flooding. Gray dashed sections have missing elevation or lie within approximate bridge masks. Bridge decks and their structural safety are unassessed; nearby approaches may also be inside these masks. The total exposed distance sums only assessed surface sections. The ±0.5 m range is a terrain sensitivity experiment, not a measured confidence interval.
How the 3D water works
Water is a flat continuous surface clipped to sampled terrain. Decorative wave animation has been removed; storm playback still changes the scenario water levels. Where real terrain is available, a simple connected-inundation threshold is computed from low boundary cells of each local tile. This is a static screening approximation, not a flow or momentum solver. Ocean and sound levels rise with the same smooth teaching hydrograph. Offshore wave inputs only affect the separate wave-reach teaching check; they do not change screened roadway depths. The lightweight aerial view interpolates a compact water-entry grid into a smooth raster overlay. Sharper 2048-pixel USGS imagery loads for the selected location after the small preview. The Elevation colors toggle shows a shaded cream-to-brown height surface prepared from the full source grid. The fixed scale emphasizes low ground from 0 m or lower to 3 m or higher, with color anchors every 0.25 m. Labeled contours are spaced every 0.5 m up to 3 m, then at 4 m and every 2 m above that. The sequential light-to-dark warm palette, numeric legend, and contour labels reduce reliance on hue. Fine display intervals do not imply source accuracy at those intervals. Display interpolation does not add measured terrain detail or alter any elevation used in calculations. A translucent blue overlay shows scenario inundation over the elevation colors so water and ground can be read together. Road exposure uses ivory, yellow, vermilion and purple, with numeric depth categories and dashed unassessed sections. It uses the same static screening assumptions; it is not a hydraulic solver. The optional 3D view uses a bounded drawing resolution and frame rate. Underwater geometry is illustrative; the elevation tiles do not provide surveyed bathymetry. Bridge heights in the 3D illustration are schematic, not surveyed deck elevations. Vertical exaggeration changes only the display.
The dropdown lists ten main locations. The world map retains every uploaded road section, including unassessed bridge sections. The corner world map follows the viewing location and expands to the whole corridor. Selecting a point centers the roadway view. The main view can zoom out to fit the selected named road section or the entire NC-12 corridor. Its regional map and road-exposure colors remain visible beyond the study patches; detailed elevation and blue inundation are shown only within the selected patch. Detailed terrain and aerial imagery cover ten study patches. Outside these patches the lightweight view shows the actual road point on the bundled regional map; no local terrain or water footprint is extrapolated. Cross sections remain tied to the nearest study patch, with their distance labeled.
Wave reach and historic presets
The wave reach check compares the sampled ocean-side transect crest with ocean level + 0.2 × wave height × a direction factor. That factor is an illustrative teaching assumption, not a calibrated run-up or overtopping formula. It does not produce a flooding depth. Irene- and Dorian-inspired presets are hypothetical forcing on today’s route, not historical reconstructions.
What remains to be built
A predictive version needs dated, high-resolution lidar and road-crown / bridge-deck surveys, a verified common datum, spatial storm-tide and wave time series, hydrodynamic and erosion modeling, and validation against multiple observed storms. NCDOT documents the corridor’s recurring vulnerability; that history does not validate this model’s numbers.
No live weather feed, closure prediction, structural damage forecast, or evacuation advice is provided. Calculations run in your browser. Copied scenario links preserve settings; downloaded CSV files include assumptions and source metadata.
