Comparison
Sensor-led vs fixed-frequency collection
Where the two models differ, where the gap is widest, and the cases where fixed frequency is still the right answer.
Fixed-frequency collection empties every container on a set schedule regardless of how full it is. Sensor-led collection empties each container when it reaches a set fill threshold, usually 80–90%. Fixed frequency is simpler to plan and contract; sensor-led collection is cheaper to run, responds to demand spikes, and produces an audit trail. The gap between them widens with drive time between stops and with how variable demand is.
| Fixed-frequency collection | Sensor-led collection | |
|---|---|---|
| What triggers a visit | The calendar | Measured fill level reaching a threshold you set |
| Quiet locations | Emptied anyway — cost with no output | Skipped until they need it |
| Busy locations | Overflow between scheduled visits | Collected when full, including outside the usual pattern |
| Demand spikes | Cannot respond — heatwaves, events and bank holidays are absorbed as complaints | Round expands automatically; thresholds and reporting frequency can be tightened for a known peak |
| Planning effort | Low, but the plan is never revisited | Automatic daily generation, with supervisor override |
| Mileage | Fixed, regardless of need | Falls with the number of stops — Stralsund saw 54% less weekly distance |
| Service evidence | None beyond crew recollection | Every reading and lift timestamped and queryable |
| Carbon reporting | Modelled from scheduled journeys | Counted from journeys actually made |
| Estate review | Effectively impossible — no utilisation data | Fill history identifies overlapping and under-used containers |
| Contract negotiation | Frequency argued from opinion | Frequency argued from lift and fill data |
| Upfront requirement | None | An accurate container register and a sensor per container |
| Ongoing cost | Collection cost only | Collection cost plus a per-container subscription — offset by avoided lifts |
| Best suited to | Dense urban rounds where every container genuinely fills daily | Anywhere demand varies, or where drive time between stops is significant |
When fixed frequency is fine
The honest case against sensors
Sensor-led collection is not universally worthwhile, and any supplier telling you otherwise is selling rather than advising.
If every container on a round genuinely fills every day, there are no wasted journeys to remove, and a subscription buys you evidence and reporting rather than a saving. If the vehicle passes every container anyway — kerbside household rounds being the obvious case — there is no journey to avoid at all. Vejle applied this reasoning deliberately, leaving 328 of its 875 bins uninstrumented because they sit in central locations already emptied daily as part of other routines.
The two questions worth asking before anything else: how many of last month's lifts went to containers that were less than half full, and how long does a vehicle spend driving between stops? If you cannot answer the first, that is itself the argument for measuring.
Where the gap is widest
- Strongest case
- Rural and edge-of-town bring sites with long drive times
- Strong case
- Seasonal and visitor locations with volatile demand
- Strong case
- Semi-buried containers whose fill level cannot be seen
- Good case
- Street and park bins on generous fixed frequencies
- Moderate case
- Campus and estate bins — less mileage, but real labour and appearance gains
- Weak case
- Town-centre bins that genuinely fill every day
- No case
- Kerbside household rounds that pass every property regardless
Working it out
How to size the opportunity before you spend anything
Count the lifts
How many container emptyings does your operation perform in a year, on containers a vehicle travels specifically to reach? Exclude kerbside. This is the denominator for everything else.
Estimate the waste
Ask supervisors what proportion of those containers are typically under half full at collection. The estimate will be wrong, but it establishes whether the potential is 10% or 60% — and it will almost certainly be understated.
Cost a lift properly
Include the drive to reach it, not just the emptying. On dispersed rural rounds the travel is the majority of the cost, which is why Langeland's saving came as much from eliminating an inspection round as from fewer collections.
Multiply those three and you have an order of magnitude. Then measure a single round for 90 days and replace the estimate with a number. We will help you build the model, including the parts that argue against buying anything.
Questions
Choosing between the two
Is sensor-led collection always cheaper than fixed frequency?
No. It is cheaper wherever a meaningful share of current journeys go to containers that did not need emptying, which is most operations but not all. On a dense urban round where every bin genuinely fills daily there is little to recover, and the subscription buys evidence and reporting rather than a saving. On kerbside household rounds, where the vehicle passes every property anyway, there is no journey to avoid and no case at all.
What fill threshold gives the best balance?
80–90% is the established starting range. Vejle flags at 80%, Langeland typically adds a container at 80–90%. The variable is headroom: how long between the reading and the visit, and how bad an overflow would be at that location. A rural bring site reached twice a week needs a lower threshold than a town-centre bin you can reach the same afternoon. A promenade bin in August warrants a lower threshold than the same bin in November. Most operations tune thresholds during the first couple of months.
Can we run a hybrid model?
Yes, and most mature deployments do. Instrument the containers where the journey is discretionary; leave the ones already passed daily on a fixed routine. Vejle instrumented 547 of 875 bins on exactly this logic. Hybrid is not a compromise — it is the correct answer, because it puts the subscription only where it changes a decision.
How does this affect a waste collection contract?
It changes what the contract can be written against. Fixed-frequency contracts specify visits; sensor-led operation makes it possible to specify outcomes — containers not exceeding a fill threshold, response time from flag to lift, evidenced service history. That is a better contract for a commissioning authority and, for a contractor confident in its service, a better one to be measured by. It also removes most of the ambiguity that makes missed-collection disputes unresolvable.
Do the sensors pay for themselves?
Where there is genuine slack in the current schedule, quickly. Stralsund reported that its 35-bin pilot paid for itself in under a year on avoided collections and mileage alone, and extended the deployment on that basis. Fanø achieved a 20% reduction in emptyings within two months of switching on. Both had generous fixed frequencies to begin with. The point of a measured pilot is to find out whether yours does too, before committing to anything larger.
Next step
See what your own bin data would say
A 90-day pilot on one round tells you exactly how much of your current collection effort is going to bins that were not full. No commitment beyond the pilot, and you keep the data.