Distance Laser Live

How many heavy vehicles really cross a bridge, and how heavy are they? The Distance Laser Live measures the deflection of the superstructure at midspan with every crossing. From the shape of the signal, the platform assigns the vehicle to a weight class, counts heavy traffic and reports unusual loads.

Request a quote How it works
  • Up to 100 Hz
  • Accuracy ±1 mm
  • Weight classes via AI
  • Real-time alerts
Distance laser for deflection measurement, cut out

Indirect load measurement

Using the structure as a scale

Every crossing deflects the superstructure slightly. How far and for how long depends on the weight of the vehicle. The Distance Laser Live measures this response, without any intervention in the carriageway or traffic.

Every crossing captured

With up to 100 readings per second, the laser records a complete deflection curve for every crossing, not just a single value.

Weight classes instead of estimates

Peak value, duration and shape of the curve are analysed. An AI model assigns each crossing to a weight class, for example below 7.5 t, 7.5 to 16 t, above 16 t or above 40 t.

Calibrated on the structure itself

Reference runs with vehicles of known weight determine which curve belongs to which load. The classes therefore apply to exactly this bridge.

Contactless measurement

The laser measures from the superstructure to a fixed reference point below it. Nothing is installed in the carriageway or surfacing, and traffic continues undisturbed.

Overloads reported immediately

If a crossing exceeds the defined class or deflection, an alert is sent immediately. This helps to check load restrictions.

Power as available on site

The live gateway runs on a solar module, mains power or a buffer battery and transmits via LTE. Up to two distance lasers share one gateway.

Measuring principle

From the crossing to the weight class

The distance laser sits at midspan below the superstructure and continuously measures the distance to a fixed reference point. When a vehicle crosses the bridge, this distance briefly becomes smaller. It is exactly this signal that is analysed.

DeflectionDistance laser at midspanReference pointrigid, independent of the structureDeflection signal of one crossingTime
Schematic illustration, not measured values.
  1. 01

    Vehicle crosses the bridge

    The load of the vehicle deflects the superstructure.

  2. 02

    Deflection is measured

    The laser records the vertical deformation at up to 100 Hz.

  3. 03

    Signal is analysed

    Raw data are filtered; peak value, duration and shape of the curve are determined.

  4. 04

    Weight class is assigned

    An AI model assigns the crossing to a weight class based on the calibration.

  5. 05

    Counting, reporting, alerts

    Results are counted, shown as daily, weekly and monthly statistics, and reported in case of overload.

Referencing and calibration

Reference runs first, then regular operation

To turn a deflection into a weight class, the system needs comparison values from the structure itself. Vehicles of known weight cross the bridge several times. The measured curves form the basis for thresholds and for the AI model in later operation.

  • Several crossings per vehicle type
  • Known gross weights, ideally with documented axle loads
  • Different speeds
  • The same lane where possible

Calibration is repeated regularly so that the assignment remains correct when conditions change.

7.5 t16 t26 t40 tDeflectionTime
Schematic illustration, not measured values.

Technical data

Specifications at a glance

Distance laser for deflection measurement, cut out
Measured quantity
Distance to the reference point, giving the deflection at midspan
Measuring range
0.5 to 500 m (with reflective foil at the reference point)
Accuracy
±1 mm (2σ), ±0.5 mm (1σ)
Repeatability
±0.3 mm (2σ), ±0.15 mm (1σ)
Sampling rate
up to 100 Hz
Measuring mode
Peak value, duration and shape of every crossing, assignment to weight classes
Expandability
up to two distance lasers per live gateway
Data transmission
LTE, with buffering and local storage in the gateway
Power source
Live gateway with solar module, mains power or buffer battery
Ingress protection
IP65
Sensor
red visible laser, laser class 2
Form factor
140 × 78 × 48 mm, 350 g
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Applications

What operators use the data for

Checking load restrictions

After a bridge has been downgraded to a lower load class, the count shows whether and how often heavier vehicles still use it.

Safeguarding vulnerable bridges

On bridges with prestressing steel at risk of stress corrosion cracking, or without proven warning behaviour, the measurement makes overload events visible until the replacement is built.

Counting heavy traffic

How many vehicles of which weight class use a bridge is a basis for reassessment, remaining service life and traffic planning.

Complementing deformation monitoring

Together with tilt sensors, it shows whether the structural behaviour changes over time and which loads act on it.

Prerequisites

  • Fixed mounting at midspan below the superstructure
  • Clear line of sight from the laser to the reference point
  • Stable reference point independent of the structure
  • Power at the gateway: solar, mains or buffer battery

Limits of the method

  • Not a calibrated weighbridge, but a reliable classification
  • Accuracy depends on structural stiffness, speed, lane and multiple vehicles on the bridge
  • Temperature and environmental influences affect the signal
  • Regular calibration recommended

Live or long-term

Individual crossings or the trend

The Distance Laser Live shows what happens with every crossing. For the question of whether the deflection changes over months, there is the long-term variant.

Tilt sensor with radio antenna, cut out

Long-term

Tilt sensor with distance laser

Battery-powered at midspan, measures the deflection at an interval with 0.1 mm resolution. The right choice for deflection trends over months and years.

To the Tilt Sensor
Heavy traffic on a bridge

Application

Traffic load monitoring

How traffic loads are recorded and assessed, and which measuring methods can be used.

To traffic load monitoring

Related solutions

The sensor as part of a solution

Traffic load monitoring

Traffic load monitoring

Record traffic loads and assess their effect on the structure.

Learn more
Stress corrosion cracking

Stress corrosion cracking

Monitor prestressed concrete bridges with vulnerable prestressing steel until the replacement is built.

Learn more
Bridge monitoring

Bridge monitoring

Monitoring for bridges under construction and in service, from the pier to the superstructure.

Learn more

Infrasolute platform

Load events on the platform

Every crossing appears with its weight class on the Infrasolute platform, as an individual event and in daily, weekly and monthly statistics, with an alert in case of overload.

Platform modules

Monitoring & Alerting Limit values, alarm chain by email and SMS AI Analytics Anomalies, correlations, questions to the data Lifetime & Forecast Trends, ranges, remaining service life
The platform at a glance
Bridge as a 3D model on the Infrasolute platform, measuring points coloured by status
Sample view

Want to know what crosses your bridge?

Describe the structure, the span and your question to us. We check the mounting at midspan, the reference point and the procedure for the reference runs.

Request a quote All products
Peter Nater Peter Nater
FAQ

Frequently asked questions about the Distance Laser Live

How does indirect load measurement work?
The distance laser sits at midspan below the superstructure and continuously measures the distance to a fixed reference point. With every crossing, the superstructure deflects and the distance briefly becomes smaller. From the peak value, duration and shape of this curve, the platform assigns the vehicle to a weight class.
Does the Distance Laser Live replace a weighbridge?
No. The method is not a calibrated weighbridge. It uses the response of the structure and provides a reliable classification of vehicles and load ranges. Accuracy depends, among other things, on structural stiffness, speed, lane, the number of vehicles on the bridge at the same time and temperature.
How is the system calibrated?
With reference runs: vehicles of known gross weight, ideally with documented axle loads, cross the bridge several times and at different speeds, preferably in the same lane. The measured curves form the basis for thresholds and the analysis model. Calibration should be repeated regularly.
What does the structure need?
The laser is fixed at midspan below the superstructure and needs a clear line of sight to a stable reference point that is independent of the structure. The live gateway is powered by a solar module, mains power or a buffer battery.
What does the operator see?
The Infrasolute platform shows individual events as well as daily, weekly and monthly statistics by weight class. Unusual loads trigger an automatic alert.

Project inquiry

Enquire about the Distance Laser Live

Tell us about the structure, the span, any load restriction and your question. We recommend the measuring position, reference point, weight classes and calibration procedure, and get back to you promptly.

+49 6742 8599600 DE +41 41 670 00 11 CH [email protected]
Project inquiry