Begin with the face list rather than the vehicle length
Estimates resting on overall length fail because length is not work. A five-axle tractor-trailer and a rigid of similar length can differ hugely in what has to be touched. Write one row per face and keep the fleet's own vocabulary: cab exterior and roof; glass and mirrors; wheels, hubs and drums; chassis rails, crossmembers and the underside of the tip body or box; cab steps and entrance wells; the coupling area and fifth-wheel plate; mudguards, spray flaps and valances; fuel tanks, battery box and air tanks; the tail area, ladders and handles; trailer skirts and the inner faces of any lift panels. Next to each row note the two things the figure depends on: what sits on that face, and how the operator reaches it.
Reach is the column most plans leave blank. A face cleaned from the ground, a face cleaned off a step, and a face cleaned while lying on the deck beneath a trailer cost three different amounts of time, and the last two bring posture, a stand-by rule or a permit with them. Mark every face needing a step, a crawl, a crouch or a ladder before any method is picked, because those faces set the pace of the whole job.
Classify the soiling, since soiling sets the pass count
Loose dust and splashed mud come away with volume and pressure. Road film - the thin grey staining running down the flanks and around the arches - needs heat plus a short dwell, then a brush or a wipe, because it is bonded rather than resting on top. Brake dust and oily splatter near the drums, hubs and chassis behave like grease and will not move the way mud does. Tar and rubber smears on the lower band are a separate problem again, and any surface carrying a coating of unknown history is a question, not a task.
Logging soiling face by face is what makes the figure survive contact with the fleet. A tipper back from a wet site and a curtainsider back from a depot layover are not the same job on the same vehicle; they are different jobs that happen to share a plate. Define a small set of named soiling states, assign one to each face group, and let the state decide how many passes follow. Anything you leave as "dirty" gets judged by feel every time.
Pick the mode on water and dwell, not on strength
The two settings a crew argues over are not stronger and weaker; they draw different volumes of water and need different dwell. A drier setting puts heat and vapour against a bonded film and leaves the residue on a cloth or brush, which suits painted panels, joints, cab steps, fittings and any face where standing water is a problem. A wetter setting, or hot water, carries debris away and suits the heavily soiled chassis, wheels and underside, at the cost of run-off somebody must route and permit. The machine's own rows decide what it switches between - the pages for the mobile driving-style units and for the Fixed Steam Cleaning Machine PowerDe HW02 both list a choice between dry steam output and wet steam output, and the mobile range sits around indoor garages and tight outdoor parking. None of that is a truck-cleaning claim; the vehicle's face list and the site's drainage rules decide the mode.
Two warnings belong beside any mode choice. The temperature a generator page publishes is not the temperature delivered at the nozzle across a long hose, and a tank capacity is not a working length - refill stops and hose changes are minutes, and they recur per vehicle rather than once per shift.
Time the blocks, not just the spraying
A figure that counts spraying alone is not a figure. Use six named stages and give each one minutes.
Isolation and arrival state. Engine off and cool enough to touch, keys in the designated place, parking brake on, wheels chocked, surfaces recorded as found before anything is wetted.
Shielding. Covering or avoiding the faces that must stay dry, and deciding where the discarded liquid goes, before the first pass.
Pass time. The work itself, counted per face group rather than per vehicle.
Dry and recheck. Wiping, drying the joints and sills, then looking at the same faces again in the same light.
Restore. Taking covers off, replacing anything moved, and clearing the bay for the next vehicle.
Hand-back. Signing or recording that the truck may move, which is where a fault gets noticed by someone other than the operator.
Add two hidden items that break most plans: walking and re-positioning between faces, and the queue. On a yard where the vehicle has to wait, hold, or be shunted twice, the crew's minutes and the yard's minutes are different numbers and both belong in the schedule.
Hold the boundary where cleaning stops
Heavy vehicles have faces that carry risk, and a figure ignoring them is optimistic in the wrong direction. Keep heat and directed liquid away from brake friction surfaces, wheel-bearing seals and hubs, electrical connections, alternators and starters, instrument faces, radiator and intercooler fins, air-line and cable couplings, printed safety markings, cab interior trim and upholstery, and any area that has been repainted, filled or wrapped. Where a face sits on that list, name what replaces the pass - a wipe, a brush, a dry cloth, a hand finish late in the shift - and accept that the replacement brings its own minutes. Those minutes belong in the estimate.
That boundary list also explains whether a quotation can be read at all. Ask the supplier, for the exact unit being quoted, for their exclusion list and the replacement they recommend for each item. If nobody can produce one, that answer is information too.
Site conditions: the other half of the clock
Ask what the facility controls, and write the answers down before quoting a duration. Can the vehicle be held for the whole window, or only part of it? How far is the wash position from the parking positions, and how far does the crew walk with a hose? Which drain is permitted for the discarded liquid, who granted that permission, and what must be intercepted upstream before the liquid arrives? Is power available at the work position, or does the cable cross a traffic lane? Is the position covered, and what happens in frost, rain or high wind? Does the same bay serve the next vehicle, so that drying time becomes queue time?
The discarded liquid deserves its own line in the schedule, not a footnote. On a heavy vehicle the volumes exceed a car wash and the soiling is heavier, and the silt and oil handling that follows is a facility decision with an assigned owner and a recurring cost.
Measure one bounded trial before publishing a number
Choose one vehicle of the type that dominates the fleet and one face group from the survey, tape the boundary on the ground, and clean it the way the finished routine would be cleaned, with the operator, the tool and the number of passes the plan intends. Photograph the taped faces before, framed close enough that the surface texture reads rather than the shine. Write the stop conditions down before the first pass: what ends the trial if a coating lifts, if water finds a cable run, or if a face fails the check twice. Record the six stages separately, then repeat the same face group once more and use only the timings logged on that repeat.
That repeat is not a nicety. The first carries learning: the crew finding the reach, the hose snagging, the shielding being reworked. Any number taken from the first pass will be quoted to management as the steady-state figure and will fail within a month. Two measured runs, drawing on the later one, is the sole basis for a duration that stands up.
Convert the measurement into a per-unit rate, then into a schedule
Turn the trial into something repeatable: minutes per face group, per soiling state, per operator, for one named vehicle class. Then add the face groups up for each class in the fleet and you have a per-class figure with a source. Where a group was not trialled, mark it unmeasured rather than folding it in - the gap stays visible, and it is the first thing to close. What the vendor's own pages publish no rate per vehicle length or per square metre for PowerDe cleaning equipment, so a supplier offering a confident per-vehicle figure with no measured basis should be asked how it was obtained.
Publish the result as one page per vehicle class, taped in the wash position: face group, soiling state, mode, passes, exclusion and its replacement, the drying step that ends each wet line, and who to tell when a face fails. Give the page a review date, because a fleet that changes routes or trailers will change its soiling states within a season.
What to require in writing before committing to a duration
Ask the supplier to provide those same rows for the exact machine, not the brochure: the supply arrangement at the work position and what it connects to on a yard tap; the voltage and the power arrangement there; the water capacity and the refill assumption behind a working length; hose and wand reach and what that reach does at the far side of a trailer; the switching between modes and what changes when the crew switches; the protection features recorded for that unit; the wear parts, the replacement interval and the basis for that interval; plus the boundary list discussed earlier. Where a row is missing, that is the question to have settled on paper before the figure is signed, not after the first truck is in the bay.
A fleet whose mix changes - more tipper work in one season, more depot running in the next - needs the survey revisited rather than the number defended. Where the routine itself is what is being designed rather than timed, customized steam cleaning equipment work begins from that same face list and trial, which is why the survey is worth writing properly the first time.
What this method does not give you
It does not give a universal figure for cleaning a heavy transport truck, and no such figure exists. It gives a duration for a named vehicle class, on named soiling states, under the facility's own drainage and power conditions, with a named boundary list, measured twice by the crew who will do the work. That is the version a yard can plan against, price against, and audit when the estimate is missed - and the version a supplier can be held to.
