Nine hundred pallets a day across a dimension nobody drew
A cross-dock unit opens with twenty-four doors and everything on it works. The levellers were commissioned, the seals fit, the restraints interlock with the door lights. What nobody notices for a fortnight is that the floor came out low against the yard — the finished floor level was fixed by a flood-risk condition and a freeboard allowance, and the truck court was then graded to fall away from it, and between those two decisions the sill ended up sitting under the average trailer bed rather than a little above it. Every leveller on the run spends its working life in the upper part of its stroke. The forklift climbs out of every trailer.
That costs seconds, and seconds are the unit this building is measured in. It also costs lips: a leveller worked near the top of its range lands its lip shallower on the trailer floor, and shallow lips get caught by pallet trucks and bent. None of it can be fixed later, because the thing that would have to move is the slab.
So the useful way to hold a dock in your head is not as a shopping list of equipment but as a chain of levels running from the warehouse floor down to the drain the yard falls to: floor, sill, leveller stroke, trailer bed, apron surface, court, outfall. Every link in that chain is owned by a different person — the architect, the equipment supplier, the operator's transport manager, the drainage engineer — and the chain is closed at the moment the floor level is signed off. Everything below is about closing it deliberately rather than discovering it.
The sill height is a fleet survey
There is no correct dock height. There is a distribution of trailer bed heights that will actually present at this building, and a sill chosen so the busiest part of that distribution sits nearest level and the tails stay inside what the leveller can reach. Getting that distribution means asking the operator for the fleet and asking again for the carriers they subcontract to, then going out with a tape and measuring, because the number a transport manager quotes is the specification of a new trailer and the yard is full of eleven-year-old ones.
Measure loaded and empty, and measure the same trailer twice. Suspension travel is the largest single variable in the whole exercise: an air-ride trailer sits at ride height while it is running, drops when the bags are dumped, and drops again under a full load, and a mechanically sprung trailer moves less but starts from a different place. Everything else is smaller but stacks — an insulated floor puts a refrigerated trailer above a dry van on the same chassis, worn drive tyres pull a rigid down, and a trailer standing on its landing gear rather than under a tractor is at whatever height the driver wound the legs to.
The decision this produces is a compromise, and it is worth writing down as one. Set the sill for the trailers that arrive most often, check that the tallest and the lowest are both still inside the leveller's published above-dock and below-dock range, and then check separately whether anything on the list cannot use a dock at all. Rigid vans with tail lifts, curtain-siders loaded from the side, and small parcel vehicles are all common on a distribution yard and none of them wants a dock face; they want a bay on the ground with room to work beside it, and that bay is a piece of the same court.
Where the operator is not known — a speculative unit, a shell built for a tenant to be found — the honest answer is not to guess a bed height but to buy range. A deeper pit, a longer platform and a leveller specified toward the middle of its class costs a fraction of a slab and is the only thing on this page that can absorb a tenant nobody has met.
| Variable | Effect on bed height | Where it bites |
|---|---|---|
| Air suspension dumped at the dock | Drops, and by the largest single amount on this list | Some carriers dump as standing procedure and some do not, so the same door sees both on the same day |
| Load in the trailer | Drops as the suspension compresses | A trailer arrives loaded and leaves empty, so the leveller crosses part of its range during one visit |
| Insulated floor on a refrigerated trailer | Sits higher than a dry van on the same running gear | A chilled operation and a dry operation in the same building want different sills |
| Tyre size and wear | Lowers as tyres wear down; changes with a re-shod fleet | Quietly moves the whole distribution over the life of a contract |
| Uncoupled and standing on landing gear | Whatever the legs were wound to, nose-high or nose-low | Drop-trailer operations, where the trailer is left at the door for hours without a tractor |
| Apron gradient under the vehicle | Barely changes the height at the sill; tilts the floor inside | Covered below — it is the effect that gets predicted backwards most often |
A leveller is a ramp, and something has to climb it
Once the sill is fixed, the leveller's job is to bridge whatever is left between it and the trailer floor, and the shape it bridges with is a ramp. The grade of that ramp is the height difference divided by the length of the leveller platform, which is why two units with identical published working ranges behave completely differently: a short platform reaching the same height is a steeper climb, and the climb is what the truck feels. A published working range says the machine can reach that far. It does not say a rider truck with a double-stacked pallet can work there all shift.
Grade shows up in four places at once. Ground clearance under a low-profile powered pallet truck runs out at the break where the pit floor meets the platform. Traction and braking on a loaded electric truck fall off going up. A tall load leans, and the operator compensates by driving slower. And there is not one grade break but three inside the length of a single leveller — dock floor to platform, platform to hinged lip, lip to trailer floor — which is what makes the crossing feel worse than the arithmetic suggests.
Choose the leveller type against the operation rather than the budget line. A pit leveller is the default and needs a formed concrete pit cast into the dock face. An edge-of-dock unit bolts to the face and is cheap, but it has a short reach and a correspondingly narrow range, so it belongs where the fleet is uniform and the height difference is small. A vertical-storing leveller sits with its platform upright when not in use, which lets the door close onto the pit floor rather than over a stowed lip — the reason it is the usual answer for a temperature-controlled dock, where a leaking seal at the leveller is a running refrigeration cost rather than a draught.
The scheduling consequence is the one that catches design teams. The pit is a reinforced concrete box with cast-in angles and anchors, and its dimensions come from the specific manufacturer's installation drawing — not from a generic detail, and not from the model above it in the same range. That means the leveller has to be selected before the reinforcement drawings for the dock wall are issued, which is far earlier than an equipment package would normally be let. A pit built to the wrong drawing is broken out and recast, and it is holding up the slab while that happens.
- Take the highest and lowest measured bed heights from the fleet survey, not the specification sheet.
- Subtract the proposed sill level from each to get the rise the leveller has to make, above dock and below dock.
- Divide each rise by the platform length of the unit being considered — the platform, not the platform plus the lip.
- Compare the two grades against what the operator's own trucks are rated to climb loaded, which their supplier will state.
- Where the worst case is uncomfortable rather than impossible, take the longer platform before you take a different sill: the pit is cheaper to deepen than the slab is to raise.
Rise is the gap between your proposed sill and a measured trailer bed; run is the leveller platform length. Do it twice — once for the highest trailer on the survey and once for the lowest — because the two answers are the grades a loaded truck climbs and descends, and they are what the operator will judge the building on.
The vertical change in height over the run.
The horizontal distance over which the rise occurs.
Slope grade
8.974 %
- Angle
- 5.13 degrees
They open the calculator with your figures already in it
Slope & Grade Calculator: 8.97 % — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
What this calculation does not cover
- Run is taken as the true horizontal distance between the two ends, and nothing converts a tape laid along the sloping face into that horizontal — measure along the surface instead and the grade reads lower than the ground really is, with the gap widening as the slope steepens.
- Rise is read as a magnitude only, so a drop and a climb of the same size return the same positive grade and a negative entry is floored to zero; which end is higher stays your own note rather than something the answer carries.
- Both figures describe a single straight line drawn between the two points you measured, so any crest, dip or bench sitting between them is averaged away, and cross-fall across the width of a drive or path is not part of the arithmetic at all.
- The output covers grade percent and the matching angle; the sloping distance itself — what you would order ramp board, handrail or edging against, and always longer than the run — is not worked out, nor is the result expressed as the 1-in-X ratio that specifications are often written in.
- No ceiling is applied to the outcome: a 2% fall and a 45% bank come back with identical confidence, and the accessible-ramp and driveway grade figures quoted in the questions below are context for reading your number, not a test the calculation runs against it.
Door centres, and the yard depth they buy
Door spacing looks like an elevation decision and is really a yard decision. The centre-to-centre dimension has to carry the trailer's own width, the projection of whatever seal or shelter is fitted around the opening, a tolerance for a trailer that arrives a few degrees out of square, and the structural grid — because a column landing in a door opening is a redesign and a column landing between two doors is free. Those four get reconciled once, and the result then sets how much yard the building needs in front of it.
The relationship runs the wrong way round from most people's intuition: the tighter the door centres, the deeper the truck court has to be. A driver reversing into a narrow bay between two parked trailers has to arrive more nearly square, which means straightening earlier, which means more room in front of the dock face to do it in. Widen the centres and the same driver can take a shallower approach. Buying door centres is buying yard depth, and on a constrained site that trade is usually the one that decides how many doors the building gets at all.
Then there is the direction of the back-in. A driver reversing toward the driver's side can watch the trailer down the length of the vehicle; reversing to the blind side is done on mirrors and takes longer, and takes more bites. A court laid out so that the natural circulation forces every approach to the blind side works — it just works more slowly, every movement, for the life of the building, and it shows up on the dock bumpers within a year.
| If door centres go | The yard | The building |
|---|---|---|
| Tighter | Needs more depth in front of the face for the reverse, and the neighbouring trailer becomes the governing obstruction | Fits more doors on the same elevation; door surrounds, seals and any shelter frame start competing for the pier between openings |
| Wider | Tolerates a shallower court and a less square approach; more forgiving of an unfamiliar driver at night | Fewer doors on the same elevation; easier to land the structural grid without a column in an opening |
Read the band this returns as the clearance to the trailer parked in the next bay rather than to a kerb, and remember what it is: a single-unit geometric envelope. It is the right tool for testing whether the court has any chance at the centres you are proposing, and the wrong one to submit — the combination unit's own reversing template from AASHTO's Green Book is what goes on the drawing.
Front axle centre to rear axle centre on the design vehicle.
How far the front wheels can be turned at full lock.
From the front axle centre forward to the foremost point of the body.
Overall width across the body, mirrors excluded.
Added outside the body envelope for driver variation and kerb faces.
Swept path width
17.2 ft
A single-unit bicycle-model turn at steady full lock. It does not model a combination vehicle's trailer off-tracking, a transition into or out of the curve, or superelevation, and it is a check on a published template rather than a replacement for one.
- Inside rear tyre path radius
- 28.26 ft
- Outer body envelope radius
- 45.48 ft
- Turn radius at the rear axle centre
- 32.26 ft
They open the calculator with your figures already in it
Design Vehicle Swept Path Calculator: 17.22 ft — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
What this calculation does not cover
- Swept path has height as well as width. A container being tipped, a raised tailgate or an aerial device needs vertical clearance this page says nothing about.
- Trailer off-tracking on a combination vehicle is additional and can be well beyond the tractor's own inside path.
Which way the apron falls, and what falls with it
The apron has to shed water away from the dock face. Water standing at the sill is what a forklift crosses forty times an hour, it is where the ice forms first because that strip is shaded by the trailers and by the building, and it is the one place on the site where a puddle is directly against a door opening into the warehouse. So the ground falls away from the building, and the first question is how much.
The second question is what else falls along the way. Over the strip between the dock face and wherever the water is collected, a couple of percent is not a rounding error — it is a real drop in level, and it decides whether the far edge of the court still sits above the invert it has to drain to. This is the arithmetic that closes the chain the first section opened, and it belongs at sketch stage: floor level minus sill drop minus apron fall has to leave a level this site can be built to, and where it does not, the answer is a different floor level rather than a flatter yard.
The fall also does something to the trailer, and it is routinely predicted backwards. Because a trailer pivots about a rear suspension sitting close to its own rear end, and because a coupled tractor holds the front at roughly the same height above whatever ground it stands on, the deck ends up tilting at about the gradient of the apron — while the height of the rear edge at the sill barely moves at all. The consequence is not at the sill. It is inside the trailer, where the floor now falls away from the doors, and the truck that drove down into the load has to drive back up with it. That grade adds to the leveller grade rather than cancelling it, and it is the reason the two are worth checking together. An uncoupled trailer standing on its landing gear is the exception: there, the legs set the front independently, and a badly wound pair on a falling apron will tilt the deck the other way and change the height at the sill as well.
One direction of fall must be resisted, and that is along the dock face. A run of doors shares a single sill level because it shares a floor, so any gradient running parallel to the face means the trailer at the far door meets that sill from a different relative height than the trailer at the near one — a difference that comes straight out of every leveller's remaining range for no benefit at all. Keep the face level and take the fall perpendicular to it, which means the collection line runs parallel to the building rather than the water being walked along the frontage to a corner.
Enter the distance from the dock face out to your collection line as the half-width and your proposed gradient as the cross-slope — the arithmetic is the same for a one-way fall as for a crown. What comes back is the level you have spent on drainage, and it is the number to hold against the site's existing levels before the finished floor is agreed.
The horizontal distance from the roadway's centerline crown to the edge of pavement.
The target drainage cross-slope from centerline to edge, as a percentage.
Edge elevation drop
2.76 in
They open the calculator with your figures already in it
Roadway Crown Cross-Slope Calculator: 2.76 in — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Add the equipment this sizes
This result is a specification — 2.76 in — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
What this calculation does not cover
- The edge drop is worked as one straight gradient from crown to edge, so where a crown is built as a curve rather than two flat planes only the edge point matches — the pavement at intermediate offsets sits higher, with less drop, than a straight interpolation implies.
- A single half-width and a single cross-slope stand in for both sides of the road, so an asymmetric crown, a widened lane, or a different slope left and right has to be run twice and the two drops read separately.
- Longitudinal grade is absent from the arithmetic: where the road also falls along its length, water leaves the surface on a diagonal path and the true surface gradient is the resultant of the two slopes rather than the cross-slope alone.
- The cross-slope field accepts 1% to 4% only, so a superelevated curve banked beyond that band, or a deliberately flatter section, cannot be entered here.
- Half-width is read as a horizontal plan distance, so a width tape-measured along the crowned surface instead of taken off the drawing is fractionally long and inflates the drop by a correspondingly small amount.
- The figure describes the finished pavement surface between centreline and edge of pavement — course thicknesses, subgrade profile, and any gutter pan or shoulder break beyond that edge sit outside it.
Collecting it without putting a drain under the bogies
Where the collection line goes is constrained by things standing on it. A channel hard against the dock face sits under the trailer's rear axles and inside the zone the concrete apron is there to protect, and it is also the line the leveller pit, its anchors and the bumper fixings are competing for. Move it out and it lands under the trailer bogies or under the tractor's drive axles instead. There is no position free of load, so the decision is which load the channel is detailed for — and a slot or trench drain in a truck court is a structural item with a load class, bedded and haunched to a detail, not a landscape product.
The court's edge has a related problem. A standard highway kerb-and-gutter section is designed to be driven along and occasionally over; the inside of a turning circle in a truck court is driven over constantly, at full lock, by tyres scrubbing sideways. Kerbs there get rotated out of the ground and gutter pans crack across. What the court usually wants instead is either a heavier section on a deeper foundation, or no upstand at all — a flush edge with a bound shoulder beyond it, so an over-run costs nothing and marks nothing. Whichever it is, take the cross-section off the project's own detail, because the volume follows from the section and the section here is rarely the road standard.
Enter the run and the four dimensions off the detail you have actually specified — a heavy-duty court section is not the roadway standard, and the gutter pan is usually the part that has been thickened. It volumes a straight run of one constant section, so take the perimeter that way and volume the island noses and every kerb return separately: a tight radius is not the section you entered.
The total length of the curb-and-gutter run.
The vertical height of the curb face above the gutter.
The thickness of the curb section itself.
The full width of the gutter pan, measured from the BACK of the curb across the pan — not from the curb face.
The thickness of the gutter pan slab.
Curb and gutter concrete volume
7.639 yd³
- Combined cross-sectional area
- 1.25 ft²
They open the calculator with your figures already in it
Concrete Curb and Gutter Volume Calculator: 7.64 yd³ — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
What this calculation does not cover
- Carries no allowance for what the ground takes. The section is placed on a trimmed subgrade, and over-excavation, a soft spot, or a trimmed line running 10 mm (0.39 in) low along the whole job all add concrete that no theoretical cross-section contains. Ordering the calculated volume for a continuous pour is how a run comes up short, and a short load part-way along a curb line leaves a cold joint that stays visible.
- The concrete only. The compacted granular base under the section, the tie bars or dowels at construction joints, and the filler at expansion joints are all taken off this same run length and are the items most often left off the order — the base course alone is often as large a volume as the concrete sitting on it.
Moving axles, and trailers that just stand there
A truck court carries two completely different kinds of loading and only one of them is what pavement design is built to model. The moving part — trucks crossing the drive lane, circulating, approaching the doors — is a repeated-load fatigue problem, and equivalent single axle loads are exactly the right currency for it. The counting is unusual only in that it is a closed population: the traffic here is doors multiplied by turns per door per day, it is very nearly all heavy vehicles, and it all uses the same ground in both directions, so the directional and lane factors that soften a highway calculation do very little softening on a yard.
The standing part is not a fatigue problem at all. A loaded trailer left on its landing gear puts a substantial share of its weight through two small pads that do not move, for hours, in one place, and a tractor's drive axles do something similar while the trailer is being worked. That is a bearing and punching question. It is also a temperature question, because the pads do their worst on a hot afternoon when a bituminous surface is at its softest, and no amount of design life will help — the failure is a hole under a leg, not a crack in a wheel path.
Then there is what happens between those two, which the fourth-power damage relationship also does not see: full-lock turning at crawl speed. The horizontal shear a steered tyre applies while scrubbing is what shoves a bituminous surface into ridges at the head of a bay, and it is a surface-stability problem answered by mix selection and by a rigid surface where the manoeuvre is repeated in the same place. Run the traffic arithmetic to size the court and the drive lane. Do not run it to justify a flexible surface under a landing gear, because it has no term for one.
Count the yard's own movements rather than a highway AADT: doors times turns per door, doubled for in and out. Then put the directional distribution at one as well as the lane factor — it defaults to the half a two-way road is entitled to, and a yard's traffic runs both ways over the same ground. With the truck percentage close to the whole of it, that is the honest reason a small yard reaches the loading of a busy road.
Two-way vehicles per day, averaged over the year.
Share of traffic that is heavy vehicles.
Average ESALs contributed by one truck.
Share of trucks in the design direction.
Share of directional trucks in the design lane.
Analysis period for the structural design.
Compound annual growth over the life.
Design ESALs
2,840,000 ESALs
Standard AASHTO cumulative ESAL build-up. The answer is dominated by the truck percentage and the truck factor — both site data, neither guessable.
- Millions of ESALs
- 2.84 MESAL
- Design-lane ESALs per day
- 320 ESAL/day
- First-year ESALs
- 116,800 ESALs
- Growth factor over the life
- 24.3 ×
- Trucks per day in the design lane
- 320 trucks/day
- Uplift from growth over a flat assumption
- 21.49 %
They open the calculator with your figures already in it
Pavement Design ESAL Calculator: 2,837,933 ESALs — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
What this calculation does not cover
- Produces the traffic loading only. Converting ESALs into a pavement thickness needs subgrade strength, layer coefficients, reliability, serviceability loss and drainage — a separate design.
- The fourth-power damage relationship is an empirical approximation from the AASHO Road Test. It is standard practice and it is still an approximation.
- Construction traffic during the works is not included and can be a significant share of an access road's whole-life loading.
Two pavements meeting on one line
The strip in front of the doors is normally concrete and the rest of the court is normally not, which means a truck court is two pavements designed by two different methods with a joint between them. How far out the concrete runs is not a rule of thumb — it is a measurement off the trailers that will use it, taken far enough to cover the landing gear and the rear bogies when a trailer is at the door, plus whatever the tractor's drive axles need when it is coupled. That dimension comes from the fleet survey the sill height already required, which is one more reason to do the survey properly.
The two halves are designed on unrelated principles and the estimating error is applying one method to both. The flexible court is sized by layers and coefficients, and the concrete apron is a rigid pavement designed on flexural strength and on what the subgrade will support — the ground the ACI guidance for concrete site paving at industrial and trucking facilities covers, and where the thickness comes from a rigid method rather than from a structural number. Neither number tells you anything about the other, and a bid that quotes a single build-up across a whole truck court has priced one of them wrong.
For the flexible half, the term worth spending time on is drainage. The structural number method carries an explicit drainage coefficient on the unbound layers, and it is the honest place to record that a court ponds at its low point or that the base has no outlet — a base sitting saturated is worth measurably less than the same base drained, and the arithmetic will show you that fixing the outfall buys more structure than another lift of asphalt. That is a better conversation to have with a client than a thickness argument. Where the two pavements meet, detail the joint deliberately: a formed vertical face for the bituminous material to butt against rather than a feather, and load transfer across the line, because a feathered edge at a concrete joint is the first thing on the yard to ravel and the joint is crossed by every trailer that enters the building.
Run the court section twice — once with the drainage coefficients at unity, and once with them where a saturated, outlet-free base honestly puts them. The difference between the two structural numbers is what the drainage detail is worth in pavement, expressed in the only currency the client's cost plan understands.
The AASHTO structural layer coefficient for the asphalt surface course.
The thickness of the asphalt surface course, as used directly in the AASHTO SN equation.
The AASHTO structural layer coefficient for the granular or treated base course.
The thickness of the base course.
The AASHTO drainage coefficient applied to the base layer's contribution to SN.
The AASHTO structural layer coefficient for the subbase course.
The thickness of the subbase course.
The AASHTO drainage coefficient applied to the subbase layer's contribution to SN.
Structural Number (SN)
3.54 SN
Layer coefficients and drainage coefficients must be selected per AASHTO 1993 guidance (or your DOT's pavement design manual) for your actual materials — this calculator only sums the SN equation from values you provide; it does not select or validate those coefficients, nor does it determine whether the resulting SN meets your required design SN from traffic (ESAL) analysis.
They open the calculator with your figures already in it
Flexible Pavement AASHTO Structural Number (SN) Calculator: 3.54 SN — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Add the equipment this sizes
This result is a specification — 3.54 SN — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Every band is at the thickness you entered, and the vertical scale is the horizontal scale — so a thin course looks thin. The width shown is a fixed slice; this drawing is about depth.
What this calculation does not cover
- The one layer this equation never mentions is the one holding everything up. SN describes the pavement ABOVE the subgrade; the SN you need comes from the subgrade's resilient modulus together with the design reliability, the overall standard deviation and the serviceability loss you are prepared to accept. The same 3.5 that is generous over a stiff gravel subgrade is thin over a soft clay, and nothing entered here distinguishes the two.
- Layer coefficients are not material constants. They are a curve fit to the AASHO Road Test — two years of trucks over one subgrade in one Illinois climate, finished in 1960 — and axle loads, tyre pressures and mix designs have all moved on since. A section far outside that envelope, whether from very heavy gear, high tyre pressures or deep seasonal frost, is extrapolation, which is precisely why most state DOTs publish their own calibrated coefficients rather than the guide's.
- Three layers and no more. There is no term here for a lime- or cement-stabilised subgrade, for geogrid or geotextile reinforcement, or for an existing pavement being overlaid — an overlay is designed from the effective SN of what is already in the ground, a different calculation entirely. Entering a stabilised layer as though it were granular base is how that value gets quietly lost, or invented.
Bumpers, restraints and the edge of an open door
A dock bumper is a dimension before it is a fitting. Its face is where the trailer stops, so its projection subtracts directly from how far the leveller lip reaches onto the trailer floor — and a thicker bumper, which is exactly what a yard with tall trailers or a falling apron tends to want, is buying standoff at the cost of lip purchase. Fix bumper projection and lip length together, from the same drawing, and detail the fixings on the assumption that the bumpers are consumable, because they are: the difference between replacing a set in an afternoon and closing a door for two days is entirely in how they were anchored.
Holding the trailer still is a safety requirement with a documented floor. Under the OSHA powered industrial truck rule, the brakes of a highway truck are set and chocks are placed under the rear wheels before it is boarded by a forklift, and fixed jacks are used where they are needed to stop a semitrailer that is not coupled to a tractor upending under the weight of the truck driving into the nose. A powered restraint engaging the rear underride guard or the wheel does the same job more reliably and can be interlocked with a light outside and a light inside, which is what actually stops an early departure. The ANSI MH30 series covers this family of equipment — levellers, portable dockboards and vehicle restraints — and the interlock logic and the fallback when the restraint cannot engage a particular trailer belong in the operator's written procedure, not in a laminated notice.
The dockboard, where one is used instead of a fixed leveller, has its own rule: it must carry the load intended for it, be secured against displacement, and have run-off protection at the sides. That is a specification, an anchorage detail and a storage position — settle the third at design, because a dockboard with nowhere to live ends up leaning against the wall inside the door.
Last, the opening itself. A dock door standing open with no trailer at it is an unprotected edge with a drop to the yard, and it is used by people on foot far more often than anyone plans for. The adopted walking-working-surfaces rules and the building code's guard provisions both have exceptions written for loading docks, and both exceptions are narrow enough to be read rather than assumed — the practical answer is a barrier, gate or chain that is part of the door's operation rather than a thing somebody has to remember, and a separate pedestrian route down to the yard so that nobody has a reason to jump.
The window closes at the reinforcement drawing
The chain that started at the floor level can only be adjusted while all of it is still on paper, and the point of no return arrives earlier than the equipment procurement programme suggests. Once the dock wall's reinforcement is detailed around a pit of a particular size, the leveller model is fixed. Once the slab is poured, the sill is fixed. Once the court is formed to falls, the tilt inside every trailer that will ever park there is fixed. Everything on this page is cheap to change for about six weeks and then it is not.
So finish the survey, close the arithmetic, and hand on what the next person needs: the measured bed heights the sill was set from, the leveller's platform length and published range, the grades a loaded truck climbs at both ends of it, the apron gradient and where the collection line runs, the joint line between the two pavements, and the restraint interlock as commissioned. In service the parts that fail are bumpers, lips and the joint between concrete and asphalt — and the one that gets rebuilt is whichever pavement was priced with the other one's method.
What has to be settled before the floor level is signed off
A dock is quantified as levels and clearances long before it is quantified as concrete, and the levels have four owners: the architect who sets the floor, the operator whose trailers set the sill, the equipment manufacturer whose pit sets the wall, and the drainage engineer who takes what is left. Close these seven against one another and the materials follow.
- A measured fleet, not a specification sheet — Bed heights taken with a tape on the trailers that will actually arrive, loaded and empty, air dumped and inflated — plus the vehicles on the list that cannot use a dock face at all and need a ground-level bay instead.
- Sill level, with the compromise written down — The chosen height, the trailers it favours, and the two extremes checked against the leveller's above-dock and below-dock range. Record why, because the next tenant will ask.
- Leveller model, platform length and pit drawing — Selected early enough to reach the reinforcement detailer. The pit is a formed concrete box to that manufacturer's drawing, and a generic detail is not a substitute for it.
- Door centres against yard depth — Trailer width, seal or shelter projection, out-of-square tolerance and the structural grid, reconciled once — then the court depth that spacing demands, taken from a reversing template rather than assumed.
- Apron gradient, and the level it costs — Fall perpendicular to the dock face and none along it; the drop over the strip to the collection line, checked against the invert the yard has to reach and against the tilt it puts inside the trailer.
- Where the concrete stops — The strip has to cover the landing gear and the bogies of a parked trailer and the drive axles of a coupled tractor. Measure it off the vehicles, then detail the joint to the flexible court as a formed vertical face with load transfer.
- Restraints, bumpers and the open-door edge — Bumper projection settled against lip reach, restraint type and interlock, and a physical barrier at every opening that a person can walk out of when there is no trailer at it.
Opens the calculators above on one screen with the dimensions from this article already filled in. Quantities only — this site publishes no price list, because local prices vary too much to publish honestly.