CulvertSense detects culvert crossings across your authority area, scores each one for flood risk and blockage likelihood, and gives your team a prioritised register — so you know where to look before the next storm, not after.
Risk-scored culvert map — real data, live platform
Storm Babet in October 2023 caused catastrophic flooding across England, particularly in Yorkshire, Lincolnshire and the East Midlands. In many cases, culverts blocked by debris backed up silently until roads were overwhelmed. Lead Local Flood Authorities are obligated under Section 19 of the Flood and Water Management Act 2010 to investigate significant flood events, yet most culverts are only inspected on a two-yearly reactive cycle, if at all.
Section 19 investigations required after significant flood events: continuous data supports your statutory duty
Typical reactive inspection cycle for culverts. Blocked inlets can fill silently between visits
Average cost of a gully clean and road closure following a culvert-related blockage incident
LLFAs: Lead Local Flood Authorities in England, each with a statutory duty to manage flood risk from ordinary watercourses and culverts
Two tiers of detection — a national open-data baseline you can view today, and a deeper survey-grade analysis when you partner with us.
We've identified 27,000+ road–watercourse crossings across England from open datasets (OS, EA), risk-scored by flood probability, infrastructure proximity, and flood history. Your authority area is ready to view today.
We run your area through our full detection pipeline using OS NGD Water Network — including buried and culverted sections that free data misses. Pilot councils see a 5–10× increase in detected crossings, each classified as culvert or bridge by OS survey data.
OS NGD Underground classification + surveyed entrance points.
NGD Underground crossing without surveyed points.
NGD Surface Level crossing.
OS-surveyed culvert entrance with no road–water intersection — urban and Victorian assets that intersection-based detection misses.
Delivered as an interactive web map filtered to your authority boundary, or exported as GeoJSON for QGIS, ArcGIS, or any GIS stack. No procurement of a new platform required.
See the register for your authority areaEvery culvert in your register is scored on two independent axes — how likely it is to fail, and how bad the consequences would be if it did — then combined into a single number you can sort and prioritise by.
We analyse upstream land cover, channel gradient, vegetation canopy, inlet aspect, watercourse size, pipe gradient, and historical flood evidence to estimate how likely each culvert is to block.
EA surface water flood probability, proximity to housing, schools, hospitals, emergency services, road classification, and flood history — combined to estimate the impact of a failure.
The two scores multiply into a single 0–100 risk number. Sort your entire register by score and work down the list — no ambiguity about which culvert to inspect first.
Likelihood 8.7/10 × Consequence 9.5/10
Using Environment Agency 1m LiDAR data, we analyse the terrain at each culvert crossing to estimate channel depth, embankment height, and pipe gradient — identifying potential structural issues without a site visit.
Channel depression depthEstimates how deep the watercourse cuts below the surrounding terrain.
Embankment heightMeasures how high the road sits above the channel — approximating the available space for a culvert pipe.
Adverse gradient detectionFlags culverts where the outlet appears higher than the inlet, indicating siltation risk or structural settlement.
Ponding indicatorsIdentifies upstream depressions where water may pool against the road embankment.
Terrain screening is indicative, not measured — it identifies sites worth investigating. Field verification confirms the findings.
Once you know which culverts matter most, add real-time water level sensors for early warning. No mains power, no cellular dependency — LoRaWAN sensors install at the inlet headwall and alert your team before blockage or overtopping occurs.
The system runs on standard off-the-shelf hardware: no proprietary lock-in, no cellular dependency, no in-field mains power required.
Select a component to explore
A waterproof ultrasonic sensor is mounted at or near the culvert inlet, pointing downward toward the water surface. It fires a 40kHz pulse, measures the echo return time, and calculates the distance to the water surface. The device wakes every few minutes, takes a reading, and transmits over LoRa radio, then goes back to sleep to preserve battery. No mains power. No cellular SIM.
A single gateway, a small weatherproof box mounted on a rooftop or utility pole, receives transmissions from sensor nodes up to 2km away in urban areas and further in open terrain. One gateway can serve dozens of sensor nodes across an area. It connects to the internet over ethernet or WiFi and forwards readings to the server. If LoRa coverage is unavailable at a site, a mobile data connection can be used as a fallback.
Once the gateway receives a reading from a sensor node, it passes the data to a server that decides what to do with it. This is where the alert rules live: if the water level crosses a set threshold, an alert fires. The server is privately operated, meaning your council's data stays under your council's control. Over time, readings are correlated against Met Office rainfall data to build a clearer picture of which culverts are most at risk and when.
When a threshold is breached, a webhook fires within seconds, delivering an alert to email, SMS, or an operations dashboard. The early warning gives highways and drainage teams time to inspect, close roads proactively, or deploy temporary measures. All data is logged, providing the continuous sensor record that supports Section 19 flood investigations.
A single upstream sensor gives you two distinct alert types: flood early warning and blockage detection, from the same hardware.
During intense rainfall, upstream water backs up against the culvert as flow exceeds capacity. The sensor detects the rising surface and fires an alert before overtopping, giving highways and drainage teams time to respond before road damage or property flooding occurs.
When debris blocks the culvert inlet, water backs up faster than rainfall alone would predict. If the sensor is mounted directly above the inlet, floating debris also reflects the ultrasonic pulse back sooner, giving a falsely high reading that triggers an alert. A blockage caught in dry weather is easy to clear. During a storm it becomes a Section 19 investigation.
Adding a second sensor downstream allows direct flow differential measurement. If upstream is rising but downstream is not, the culvert is blocked. This gives maintenance teams a precise, actionable signal even without rainfall context.
A single culvert blockage at Eel Brook, Church Minshull generated £476,000 in insurance claims, triggered an MP inquiry, and required a formal Section 19 investigation. The annual cost of CulvertSense for an entire authority area is a fraction of one major flood event.
insurance claims from a single blocked culvert (Eel Brook, Church Minshull)
homes at high risk of surface water flooding in England (NHF/EA, 2026)
typical annual cost to screen and prioritise an entire LLFA area
We are now accepting applications from Lead Local Flood Authorities in England for the first pilot cohort. The programme is structured in three stages, each evidence-gated before committing to the next. No operational dependency is required at any stage.
We deliver your authority's culvert register — every crossing detected, classified, risk-scored from 0–100, and mapped. Review the data with your team, identify priorities, and add your local knowledge. No new software to install — access via web browser.
For your highest-priority sites, add continuous water level monitoring. Each sensor installs in half a day, requires no mains power, and streams data to a shared dashboard with configurable alerts.
As your sensor network matures, we correlate water level trends with Met Office rainfall forecasts to alert your team before levels begin to rise. Available to pilot partners as it develops.
Tell us about your council and your priority culverts. We'll confirm if it's a good fit and outline the next steps. No commitment required.
Or email directly: james@culvertsense.com