UK Motorway Traffic Cameras — Live Feeds & National Highways Sensors
National Highways (formerly Highways England) operates the strategic road network of England, including all motorways and major A-roads. The agency maintains over 6,000 traffic monitoring sensors — known as MIDAS (Motorway Incident Detection and Automatic Signalling) sites — that continuously measure vehicle speed, flow, and lane occupancy across the network. Tailback surfaces this sensor data via the National Highways WEBTRIS API, visualising real-time conditions on an interactive map.
The UK motorway network carries around 20% of all road traffic on just 2% of the total road length. Understanding conditions on these roads — particularly before and during a journey — has been transformed by the open data now available from National Highways and TfL. This guide explains what data is available, how it's collected, and how Tailback makes it accessible.
How National Highways Monitors UK Motorways
The National Highways monitoring infrastructure has three main components:
- MIDAS inductive loops — Embedded in the road surface, these sensors detect vehicles passing overhead and record speed, headway, and lane-by-lane occupancy every 60 seconds.
- Roadside cameras — CCTV units monitored by Regional Control Centres (RCCs) for incident detection and management. Not all are publicly accessible.
- ANPR cameras — Automatic Number Plate Recognition cameras used to calculate journey times between motorway junctions for variable message signs.
This data is made available via the WEBTRIS API, which Tailback queries in real time to populate sensor readings across the map.
UK Motorway Coverage on Tailback
| Motorway | Key sections covered | Sensor sites |
|---|---|---|
| M25 | Full orbital (J1–J31) | 300+ |
| M1 | London to Leeds (J1–J48) | 280+ |
| M6 | Birmingham to Carlisle (J1–J44) | 260+ |
| M62 | Liverpool to Hull (J1–J38) | 180+ |
| M4 | London to South Wales (J1–J49) | 220+ |
| M5 | Birmingham to Exeter (J1–J31) | 160+ |
| M3 / M23 / M40 | Full length | 100+ each |
| A1(M) | London to Edinburgh (key sections) | 140+ |
What the Sensor Data Tells You
Each MIDAS sensor reports three key metrics every 60 seconds:
- Average speed (mph) — mean vehicle speed in each lane over the measurement period
- Flow (vehicles/hour) — number of vehicles passing the sensor per lane per hour
- Occupancy (%) — percentage of time the sensor loop is occupied by a vehicle — a proxy for density
Together, these metrics paint an accurate picture of congestion level. Heavy congestion shows as low speed, moderate flow, and high occupancy. Free-flow traffic shows high speed, variable flow, and low occupancy.
Smart Motorways and Variable Speed Limits
Significant sections of the UK motorway network have been converted to Smart Motorways, where the hard shoulder is used as a running lane and variable mandatory speed limits are displayed on overhead gantries. The main Smart Motorway types are:
- All Lane Running (ALR) — hard shoulder permanently open as a running lane; emergency refuge areas every 1.5 miles
- Dynamic Hard Shoulder (DHS) — hard shoulder open during peak periods only
- Controlled Motorway — variable speed limits only; hard shoulder retained for emergencies
On Smart Motorway sections, MIDAS sensors feed directly into the algorithm that sets gantry speed limits, creating a closed-loop system that adjusts speed limits automatically when congestion is detected upstream.
Frequently Asked Questions
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