Example data table
| Scenario | Length (m) | Total Width (m) | Thickness (m) | Net Volume (m³) | With Waste (m³) |
|---|---|---|---|---|---|
| Typical two-side parapet | 30.0 | 13.2 | 0.200 | 92.520 | 97.146 |
| Short span, thicker slab | 18.0 | 10.8 | 0.240 | 49.766 | 52.254 |
| Long span with openings | 45.0 | 14.0 | 0.210 | 130.410 | 136.931 |
Formula used
- Total deck width = clear width + left overhang + right overhang
- Slab volume = length × total width × slab thickness
- Haunch volume = length × number of girders × haunch width × haunch height
- Parapet volume = count × length × parapet height × parapet thickness
- Diaphragm volume = count × total width × diaphragm depth × diaphragm thickness
- Openings deducted = Σ(opening length × opening width × opening depth)
- Net volume = (slab + haunch + parapet + diaphragm) − openings
- Volume with waste = net volume × (1 + waste%/100)
How to use this calculator
- Select your unit system, then enter deck length and clear width.
- Add overhangs and slab thickness from the latest deck drawings.
- Enter girder count and average haunch dimensions if applicable.
- Toggle parapets and diaphragms based on your scope and details.
- Enter opening dimensions to deduct blockouts, ducts, or recesses.
- Set a realistic waste allowance and truck capacity for delivery planning.
- Press Calculate to view results above the form, then export.
Dimensional inputs and scope control
Bridge deck quantity control starts with consistent dimensions. Use centerline length and the clear carriageway width, then add measured overhangs from the edge beam. Enter the average slab thickness from typical sections, not local tapers. This calculator converts inputs to a single metric basis to reduce rounding drift and keep outputs comparable across revisions and contractor submissions. Document input sources to support audit trails and approvals.
Haunch allowances along girder lines
Haunch concrete often drives unexpected overages when girder lines are numerous. Estimate haunch volume by multiplying deck length by the number of girders and the average haunch cross section. If haunch depth varies, take a weighted average from span segments. Record haunch width at the bearing line, then confirm whether haunch is continuous or interrupted at diaphragms and drains. Use shop drawings to confirm haunch limits.
Parapet and barrier quantity breakdown
Parapets, barriers, and kerbs should be treated as separate linear elements. Use the selected count to represent one-sided or two-sided construction, then apply the height and thickness from the barrier detail. If a variable profile exists, convert it to an equivalent rectangle by matching cross-sectional area. Keeping parapet volume separate helps procurement when barrier concrete differs in mix, cover, or finish. Note offsets at approach slabs.
Diaphragm planning for early estimates
Diaphragm quantities depend on detailing and spacing rules. For quick planning, a rectangular approximation across total deck width gives a conservative estimate. Enter diaphragm depth and thickness from the framing plan, and set the count to match interior locations only. When diaphragms include blockouts, deduct them as openings to prevent double counting and keep net volume realistic during updates. Coordinate with shear keys and reinforcement zones.
Openings, waste, and delivery checks
Openings and blockouts reduce placed concrete but still affect formwork effort. Deduct each void using length, width, and depth, and group multiple similar penetrations into one equivalent opening. Apply a waste allowance to cover pumping losses, surface trimming, and test cylinders; 3–8% is common. Truckloads are calculated from the final volume, supporting delivery sequencing, pour rate checks, and standby planning. Include washout allowance for hot-weather pours.
FAQs
Q: Which deck width should I enter?
A: Use the clear deck width between edges, then add left and right overhangs. The calculator reports the total width used, so you can match it against the typical cross section and edge beam offsets.
Q: How is haunch volume estimated?
A: Haunch volume is length × number of girders × haunch width × average haunch height. If height varies, compute an average from several stations or use separate runs and add the results.
Q: How do I treat variable slab thickness or tapers?
A: Enter an average thickness that represents the placement volume over the whole span. For stepped profiles, calculate each zone separately and sum volumes, or use the thicker zone thickness with openings to approximate deductions.
Q: Why does cost use m³ even in imperial mode?
A: Costs are calculated in cubic meters to keep one consistent cost basis across unit systems. When using imperial inputs, the geometry is converted internally, then cost is applied to the final metric volume.
Q: What waste percentage is reasonable?
A: Many bridge deck pours use 3–8% depending on pumping, finishing, and access. Increase waste for complex geometry, long delivery routes, or frequent stoppages. Keep it low only when batching and placement are tightly controlled.
Q: Can I download CSV or PDF without results?
A: Downloads are created from the last completed calculation stored in your session. Run the calculator once, then use the download buttons in the results panel to export the same inputs and outputs.