Six steps: name the project, describe the crossing, establish the ground, shape the bridge, record the arch materials, then review and generate the construction drawings under your licence.
Loading your engineer record…
Your engineer record — printed in the title block of every issued sheet.
Approved by — completed at approval.
A second engineer of your organisation signs this design off at approval; their name, registration and authority appear on the issued drawings automatically.
Your surveyed section and water levels, frozen for reference. Drag the design scour and groundwater lines — or type the depths below; both are measured below the river bottom (elevation 0).
Which code family the record and terminology follow. The arch rating itself is always CS454 with its single 3.4 global factor; foundations are always checked under EC7 — those pins do not change with this choice.
How much ground investigation you have. Tier 1 works from a presumptive bearing value; Tier 2 unlocks measured strength inputs and the settlement screen.
Drained (granular) or undrained (cohesive) bearing model — changes which strength inputs apply.
Tier-1 allowable bearing pressure from tables for the founding stratum — flagged as a screening value on the sheet.
Drained friction angle — drives bearing capacity, sliding resistance and the earth pressures on the abutment.
Undrained shear strength of the clay at founding level (Tier 2, cohesive soils).
Weight of the founding soil — feeds overburden, bearing and earth pressure.
Depth to the water table below the river bed. Shallow groundwater halves effective stresses and cuts bearing resistance.
Depth below the bed at which ground good enough to found on starts — the footing must reach it.
How deep a design flood can erode the bed (manual input — always verified on site). The footing must found below scour plus an embedment margin.
Peak ground acceleration for the site. At or above 0.10 g the design routes to engineering review (East-African-Rift screen).
Foundations are checked under EC7 partial factors — a separate limit state from the CS454 arch rating, factored once. Footings are stone masonry; scour and hydrology are always site-verified.
The axle the bridge is rated against. It sets the load patch the thrust-line search pushes across the arch and the pass / fail target on the summary step.
Single-axle weight in tonnes for a custom rating target.
The site mortar. It derives an EC6 guide masonry strength (shown as unconfirmed) — the rating uses the recorded strengths below, never the guide.
The stone or block the arch ring is built from — sets the EC6 K class for the guide value.
Compressive strength of the masonry unit itself (not the wall). Raise only with test evidence.
Recorded crushing strength of the ARCH RING masonry — the value the crushing check and the rated axle actually use. Default is conservative.
Recorded strength of the bonded masonry backing over the haunches — weaker than the ring; governs backing-mode crushing on Roman arches.
Unit weight of the masonry — sets the dead load, which stabilises an arch: do not overstate it.
The mortar-mix derivation is a guide only (EC6 table values pending confirmation) and Roman arch ratings remain provisional, cross-checked against the independent RING assessment. The rating always uses the recorded values on this step.
Preview rendered server-side — generate to issue the recorded pack. The downloaded PDF is the official server copy, produced by the same engine, with the full title blocks.
Screening at N = 48 (nPos = 5) — the issued pack records this same screening. Roman arch ratings are provisional (cross-checked against the independent RING assessment); EC7 NA factor sets are unconfirmed, so foundation sizing is indicative, never a rating. Fixed abutments and a 2-D strip are assumed; values are per metre of width. Quantities are indicative, derived from the same design tables as the engineering reference model; hydrology and scour are always site-verified. Concept only — verify on site before construction; engineer-of-record verification and sign-off required.
Signed in as . In-envelope designs are issued as a stamped construction pack under your licence; designs outside the envelope are submitted for an engineering check instead.
You have inspected the parameters, site, hydraulics, quantities and drawings above. Approving signs this design off for issuance and stamps you as the approver in the title block of the construction pack.
Starting configurator…