Posted values.
Visible sources.

In plain English

Enter your full vehicle height. Red means a posted clearance is at or below that height. Yellow means it’s within the next 12 inches. Higher postings stay hidden unless you turn them on.

Always trust the signs on the road. A missing marker does not mean the road is clear. No color on this map guarantees your vehicle will fit.

How warnings work

We compare each posted number with the height you typed.

• Red — posting is equal to or lower than your vehicle.
• Yellow — posting is 1–12 inches above your height.
• Gray — higher postings, only when you choose to show them.

Use your full measured vehicle height, including roof equipment. Check the map before driving and follow the signs at the road. No category guarantees that a vehicle will fit.

What’s in this version

Official posted clearances for NYC, Long Island, the Hudson Valley, southwest Connecticut (Fairfield and New Haven counties), plus New Jersey low clearances from NJDOT’s truck map and community-mapped OpenStreetMap heights. Here’s exactly what’s loaded and how we read it.

1932 clearance records across 1912 structures in NYC, Nassau, Suffolk, Westchester, Rockland, Putnam, Orange, Dutchess, Fairfield + New Haven County (CT), and New Jersey (truck-map + OSM). A structure may have separate postings for the road on it and the road under it.

New York warnings use NYSDOT’s Posted Height Bridges layer. We read its explicit posted fields, recover whole inches from decimal feet, reject unsupported values, and retain the agency’s road names and record links. Some source names are inventory codes. When that happens, the list leads with a readable crossing or location from the same record; the original name stays in the record details.

Source downloaded: 2026-09-15. Layer update: 2026-09-15. A layer refresh is not the date each sign was inspected.

Connecticut (southwest)

Southwest Connecticut uses CTDOT posted vertical clearances for Fairfield and New Haven County towns (Stamford, Greenwich, Norwalk, Bridgeport, New Haven, Milford, and nearby). These are posted sign values from the agency bridge inventory — not inventing numbers from measured NBI fields.

This build includes 122 CTDOT posted records after town filtering. The source is CTDOT Bridges. We read PostedVertUnderClrncFt / PostedVertUnderClrncIN (under) and PostedVertClrncFt_6000029 / PostedVertClrncIN_6000030 (on), convert feet+inches to whole inches, and place each record at the polygon centroid. Town names come from Town_NBI4. When CTDOT also publishes a measured underclearance or a posted load on the same structure, we keep those as extra fields on the record — labeled as inventory / related, never as a substitute for the posted height.

Connecticut posting practice may differ from New York’s one-foot convention. We always warn off the posted number only; we never add cushion inches back in.

New Jersey

New Jersey has no public statewide “posted height” GIS like NYSDOT or CTDOT. We fill what we can from two honest sources — never inventing heights from NBI measured inventory fields.

11 NJDOT truck-map records come from the 2024 NJ Truck Map & Brochure table of structures with clearances 13′6″ or less over state and interstate highways. We convert published decimal feet to whole inches and place each row using the matching structure number on NJDOT’s Bridges FeatureServer. These are labeled as posted.

1100 OpenStreetMap maxheight tags add community-mapped signed heights across New Jersey inside our coverage box. They are labeled community — not NJDOT postings. We drop unparseable values (default, unsigned, absurd heights) and skip OSM points within about 40 m of an agency or truck-map record so the brochure wins. OSM can be wrong or stale; always trust the sign.

Corridor bans (Palisades, Garden State Parkway north of Exit 105, Pulaski) and Port Authority crossings stay on the awareness layers. A missing NJ dot still does not mean the road is clear.

NYC Open Data: legacy comparison

We also keep an older NYC low-bridge set for comparison only. It does not drive the red/orange warning layer.

We also imported 149 locations from Citywide Low Bridges. Its linked KML is dated July 2009. The catalog’s 2024 modification date does not establish that its clearance measurements were refreshed.

The NYC documentation describes expressways and parkways, excludes local streets, and includes some directional values. It does not unambiguously identify every clearance as a posted sign value. These records are preserved for comparison and overlap review; they are not mixed into the posted warning layer.

New York’s one-foot convention

In New York, many clearance signs are posted one foot below the measured opening. That NY-only rule does not automatically apply to Connecticut records. Everywhere, we warn off the posted number — we never add inches back in to guess if you’ll fit.

New York’s clearance-sign regulation specifies a legal posting one foot below measured clearance for qualifying structures under 14 feet. We use the posted number for every warning. We never add 12 inches to estimate whether a vehicle will fit.

When a record is red or orange for your height, the detail card notes this convention: physical clearance may be about a foot higher than the posted number, but driving past the posted limit is still illegal.

Checking a route (A → B)

Pick two places in NYC, Long Island, the Hudson Valley, southwest Connecticut, or NYC-facing New Jersey. We draw a driving path and list posted clearances near that line — a nearby-records check, not turn-by-turn truck routing.

From the map you can enter two places in the coverage area. We look those up with OpenStreetMap Nominatim, trace a driving path with OSRM, and list posted-clearance records within about 120 meters of that path, in order from A to B. That is a nearby-records check, not turn-by-turn directions, truck routing, or a statement that the road is clear.

Place lookup and the path line use public OpenStreetMap services. They have usage limits and no availability guarantee. No account is created. When OSRM returns meaningfully different alternatives, the map offers a path compare — we never invent extra routes. Your height, selected clearance, from/to places, and chosen path index stay in the shareable URL so a clearance card or a route check can be sent as a link.

Awareness overlays

Extra layers stay off until you turn them on (or until your vehicle profile unlocks them). They load only when requested and never feed the A→B path check.

Parkways & posted loads are one shared map dataset across the coverage area — not separate state toggles. NY parkway bans and posted-load bridges come from NYSDOT’s commercial-vehicle feed (NYC/LI plus Hudson Valley corridors such as Saw Mill, Sprain Brook, Taconic, Cross County, Hutch Westchester, Farragut, and Bear Mountain, with roadway geometry from NYSDOT’s inventory). Where a parkway has no published corridor height, we derive one from the lowest nearby posted clearance that names that parkway; corridors with no height data at all show as gray (unknown), not green. Where state feeds omit a corridor height we research NYSDOT inventory overcrossings and operator postings — we never invent numbers. CT adds Merritt, Wilbur Cross, and Milford parkway restrictions from CTDOT OSTA Parkway Restrictions, plus posted bridge weights from CTDOT Bridges. NYC-facing New Jersey adds the Palisades Interstate Parkway (including NJDOT spur/secondary geometry), Garden State Parkway (north of Exit 105), and Pulaski Skyway using NJDOT Roadway Network geometry with official restriction text (Palisades commission rules, N.J.A.C. 19:9-1.9 / NJTA, and the NJDOT Pulaski order); the NY side of the Palisades is merged into that same corridor. Checking Commercial / truck plates highlights parkway-style bans; entering a weight highlights posted-load bridges. CT parkways also carry the posted 8′ height / 7′6″ width / 24′ length / 7,500 lb combination GVW limits from that layer. For the Garden State Parkway we keep the GVWR vs registered-weight wording difference in the note instead of collapsing them.

Major Hudson crossings (GWB upper/lower, Lincoln, Holland, Bayonne, Goethals, Outerbridge) use curated Port Authority limits from the February 2026 truckers guide — height, width, and truck/tube rules — in the shared facilities / major-crossings data.

Truck routes, construction closures, and loading zones remain NYC-only. Truck routes come from NYC Truck Routes (jjja-shxy). Closures come from Street Closures due to Construction (by block) (ezy6-djsf). Loading zones come from Street Sign Work Orders (qt6m-xctn) plus Neighborhood Loading Zone signs (6pjf-tf5u). Long Island, Connecticut, and New Jersey still get the shared clearance / parkway / posted-load layers where we have sources — but not these NYC curb feeds.

Not in this build: Fort Lee / Hoboken / Newark street-by-street tonnage bans, the full NJ large-truck access network, or statewide NBI measured clearances presented as posted signs. NJ height dots use the truck-map brochure plus OSM community tags — not NBI design heights. A missing NJ clearance dot is not evidence that a road is clear.

What the map cannot tell you

• A missing marker does not mean there is no low clearance.
• Agency data can be incomplete or outdated.
• Coordinates mark structures — not always the exact warning sign.
• Clearance is separate from weight limits, commercial rules, and whether a road is legal for your vehicle.
• Vehicles taller than 13′6″ are oversized loads. This version does not support them.

A missing marker does not establish that a road has no low-clearance hazard. Agency data may be incomplete or outdated, and the NYSDOT layer does not supply lane-by-lane or directional sign details. Coordinates identify structures and may not mark the exact warning sign.

Clearance is separate from commercial-vehicle restrictions, bridge weights, road legality, and routing. An apparently sufficient posting does not make a road legal for your vehicle. Turning on truck-route or closure overlays does not validate a path.

Basemap & privacy

No account. No analytics. Your height, map view, and optional from/to places live in the shareable URL. Location is requested only when you press the location button.

The map uses a free Carto Voyager vector style over OpenStreetMap data, with attribution to CARTO and OpenStreetMap contributors. Place suggestions and path lines use Nominatim and OSRM. These are best-effort public services with usage limits and no availability guarantee. Tile and geocoder hosting must be revisited before a high-traffic launch.

No account or analytics are used. Your height, map view, and optional from/to places are stored in the shareable URL. Location permission is requested only when you press the location button.