A runway passes its friction check in autumn and fails the same check in spring, with no change to the maintenance record and no visible defect in the surface. What changed was the rubber laid down over the winter, and the fact that nobody was measuring for it until it mattered.
Surface care and winter clearing work on the same pavement, and each affects the other. This is how the two cycles fit together, and what to plan for each.
Runway rubber removal: what surface care has to balance
Surface care has to balance grip, drainage and texture.
Rubber removal restores grip, grooving maintenance preserves drainage, and winter clearing protects both by removing contaminant without gouging or polishing the surface that remains.
The balance is why the two are usually planned together rather than in separate budgets. A removal programme that leaves the grooves rounded has traded one friction problem for another, and a winter programme that polishes the surface adds to the work the removal programme has to do.
Rubber build-up and friction loss
Rubber build-up is a deposit rather than a wear process, and it accumulates where aircraft touch down.
Tyre contact leaves a film that fills the surface texture and, on a grooved surface, the grooves themselves. The effect is a gradual loss of the surface’s ability to drain water and to provide grip at the contact patch, and because it happens over many movements rather than at one moment, it is rarely visible in a routine walk-round.
The distribution matters as much as the total. Build-up concentrates in the touchdown zones rather than evenly along the runway, which is why a single friction value for the whole runway can hide a localised problem in one of them. That is the argument for measuring at fixed points, so the zones can be compared with their own history.
Removal methods compared
Removal methods differ in how they take the deposit off, and the difference shows in what they do to the surface beneath it.
High-pressure water lifts the deposit from the texture with minimal removal of the pavement itself, and it is the method most often used where the groove geometry has to be preserved. Abrasive methods remove a thin layer of surface along with the rubber, which restores texture but changes the profile, and their effect compounds if they are repeated. Chemical methods soften the deposit so it can be removed, and they bring handling and residue considerations of their own.
The practical comparison is not which method is best but which is appropriate at that point in the surface’s life. A surface that has been abrasively treated several times has less margin left, and a method that removes material has a limit that a method that does not remove material does not share.
Effect on grooved surfaces
Grooving exists to drain water and to give the tyre somewhere to displace it, and its performance depends on the geometry staying open.
Removal work that rounds the groove edges reduces the drainage performance without removing the grooves themselves, which is a failure that a visual check does not catch. Aggressive treatment over a series of cycles can reduce groove depth, and once depth is lost it cannot be restored without re-grooving the pavement.
Two practices protect the geometry. The first is to state the method and the pressure or intensity in the contract rather than the outcome alone, so the contractor’s approach is constrained. The second is to record the groove condition before and after each treatment, so that a slow loss of depth is visible across cycles rather than only at the point where performance drops.
Interaction with winter blade settings
Winter clearing changes the surface that the removal programme will later have to treat.
An edge running hard against the pavement removes more contaminant and also contributes to polishing the texture. An edge with damaged or missing inserts scores the surface, and each score is a place where the texture no longer drains. A blade set correctly leaves a surface that the next pass can work with; one set aggressively leaves a surface that looks clean and performs less well.
The interaction is visible in the records when they are kept together. A friction result that falls after a winter of hard settings, on a surface that has not received removal treatment, points at the combination rather than at either activity alone.
Scheduling around traffic
Scheduling removal work means finding a window in which the runway can be closed or restricted, which is usually the binding constraint rather than the budget.
The sequence below is the one that gets the work done without creating a second problem while it is under way.
- Establish the friction result and the zone to be treated, from the measurement record rather than from appearance.
- Confirm the method against the groove condition and the number of previous treatments.
- Agree the closure window and the area, and check the drainage route for the water or residue produced.
- Record the surface condition before treatment, including groove depth where relevant.
- Treat, then measure again at the same points and record the result against the pre-treatment values.
The fifth step is what makes the treatment auditable. A treatment followed by a measurement at the same points shows whether the method worked, and it is the evidence that justifies doing the same thing at the next interval.
Recording surface condition
Surface condition records only work if they are comparable across cycles, which means the same points and the same measures each time.
The useful record carries the friction result at named points, the groove depth and condition where the surface is grooved, the method used and its intensity, the material removed, and the weather conditions at treatment. Together those items make the next planning decision an extension of the last one rather than a fresh assessment.
The record also carries the winter side of the story. Blade settings, edge condition and the number of clearing events between treatments explain a change that would otherwise look like a decline in the pavement.
Cost and interval planning
Interval planning is a judgement between treating too often, which consumes the surface, and treating too late, which leaves friction below the criterion.
The interval that works is driven by movement numbers and by the surface’s own history rather than by a calendar. A runway with heavy traffic and an older, previously treated surface needs a shorter cycle than one with lighter use, and the record from previous cycles is what shows where the limit is.
- Start from the measured interval between the last treatments rather than from a default period.
- Adjust for changes in traffic volume or aircraft mix.
- Account for the number of previous abrasive treatments and the depth margin that remains.
- Set the next review on the friction record rather than on a fixed date.
The fourth item is what keeps the interval honest. A schedule that runs on dates will eventually treat a surface that did not need it, and the cost of that is paid in the depth that is no longer available.
What removal cannot fix
Removal restores a surface that has a deposit on it, and it does not restore one that has been worn or damaged.
Polished aggregate, a groove that has lost depth, a scored surface and a pavement whose profile has changed are all conditions that treatment does not correct. Where the friction result is low for one of those reasons, the answer is a surface treatment or reconstruction rather than another removal cycle, and repeating the removal is the expensive way to discover it.
The distinction is visible in the record. Where friction improves after treatment and then declines at the usual rate, the deposit was the problem. Where friction does not improve, the measurement has found something the treatment cannot reach.
Where the two maintenance cycles collide
The winter programme and the surface programme affect each other in four ways, and each is worth naming in the planning document.
None of the four is a fault in either activity; they are consequences of both working on the same surface.
- Hard blade settings polish the texture that the removal programme is trying to restore.
- Aggressive removal reduces the depth margin that the next winter’s settings rely on for a stable blade.
- Groove condition affects drainage in winter and grip in summer, so it belongs to both budgets.
- Friction results change for reasons on both sides, which is why the records have to be read together.
Material and test standards that a specification can reference are published by ASTM International and the American Society of Mechanical Engineers, with measurement practice published by the National Institute of Standards and Technology.
Questions for a contractor
A removal contract is easier to manage when the method and the record are specified rather than the outcome alone.
The questions below establish what will actually be done to the surface, which is the part that the price does not reveal.
- Which method will be used on this surface, and why that one rather than another?
- What intensity or pressure will be applied, and how is it controlled?
- How will the groove condition be recorded before and after?
- What happens to the water or residue produced, and where does it go?
- What evidence will be supplied to show the treatment did what was intended?
The second question is the one that protects the surface over several cycles. A method stated as “high-pressure water” without an intensity leaves the aggressiveness of the treatment to the contractor, and the effect compounds each time the work is repeated. Equipment and operational conventions for airside work come from SAE International and the American Association of State Highway and Transportation Officials, and airside practice is documented by the Snow and Ice Management Association.
FAQ
Why does rubber build-up matter in winter?
Because it reduces the surface’s ability to drain and to provide grip, and it does so gradually, so the loss is usually invisible until a measurement is taken. In winter the same surface also has to shed water and contaminant, which a polished, rubber-filled texture does less well.
Does rubber removal damage grooving?
It can, and the risk depends on the method. High-pressure water is generally the gentlest on the groove geometry, while abrasive methods remove surface material and can round the groove edges if they are applied too aggressively or too often.
Should surface care be scheduled around winter or in it?
Mainly outside it, because the work needs access and produces water or residue. The exception is a friction result that falls below the operator’s criterion during the season, which has to be addressed even if the conditions make the work slower.
How do blade settings interact with surface care?
A blade running hard on the surface removes contaminant but also contributes to polishing, and a blade with damaged inserts can score it. The two maintenance activities therefore affect each other, and recording both together is what shows the interaction.
If friction results are falling faster than the traffic justifies, send the record and the winter settings. SENTHAI will look at the interaction between the blade configuration and the surface.