REIM — Carbon and Cost

Scenarios

Create, compare and switch the assessment scenario driving every result page

Scenario builder

Toggle a lever to see the whole life impact move immediately

Extended maintenance intervalPackage All-1,510 tCO2e-0.0M NPVReduced spoil haulage distancePackage EW-01-4,380 tCO2e-0.0M NPVLow carbon station box mixPackage ST-01-7,740 tCO2e+0.1M NPVGGBS 30% plus optimised geometryPackage TU-03-23,530 tCO2e+2.1M NPVGGBS 50% blendPackage TU-03-17,170 tCO2e+2.4M NPVElectrified plant fleetPackage EW-01-12,310 tCO2e+2.6M NPV

LIVE RESULT

Embodied carbon

184,620 tCO2e

At baseline

Whole life cost, NPV

$412.8M

At baseline

Cost of abatement

—

Where the reduction comes from

Select a lever above to attribute the reduction

Levers are applied in the order listed, each against the running total. Deltas are independent, so this attribution ignores interaction between measures — the note on the saved scenarios below explains where that matters.

Saved scenarios compared by life cycle stage

A1-A3A4-A5BC

Baseline

184,620

baseline

$412.8M

LC-Alt-1, GGBS 50%

167,450

-9.3%

$418.3M

LC-Alt-2, GGBS 30% plus geometry

161,090

-12.7%

$415.5M

Full package optimisation

154,320

-16.4%

$424.6M

Extended maintenance interval

183,110

-0.8%

$408.9M

Rev12 pre-optimisation

197,340

+6.9%

$419.7M

Every saved scenario carries a full stage breakdown, not just a headline. The archived Rev12 case is retained so the improvement against the original design is auditable.

Saved scenarios

Selecting a scenario rebinds every result page and report to it

Saved totals come from a full recalculation run, so they capture interaction between measures. The builder above adds lever deltas independently and will differ slightly on multi-lever combinations.

Saved scenarios with carbon, cost and the levers applied
Scenario	Status	Embodied carbon	vs baseline	NPV	Owner	Updated
Baseline As-designed reference case, BOQ Rev14 with OPC precast lining.	Baseline	184,620	—	$412.8M	Priya Nair	14 Jul 2026, 09:42
LC-Alt-1, GGBS 50% Fifty percent GGBS replacement across all tunnel lining segments. GGBS 50% blend	Active	167,450	-9.3%	$418.3M	Marcus Adeyemi	14 Jul 2026, 10:07
LC-Alt-2, GGBS 30% plus geometry Thirty percent GGBS with optimised segment geometry, recommended option. GGBS 30% plus optimised geometry	Active	161,090	-12.7%	$415.5M	Marcus Adeyemi	14 Jul 2026, 10:07
Full package optimisation All abatement levers applied together across the five packages. GGBS 30% plus optimised geometryLow carbon station box mixElectrified plant fleetReduced spoil haulage distance	Draft	154,320	-16.4%	$424.6M	Dana Whitfield	13 Jul 2026, 15:22
Extended maintenance interval Inspection and resurfacing intervals stretched under revised durability case. Extended maintenance interval	Draft	183,110	-0.8%	$408.9M	Ravi Krishnan	11 Jul 2026, 11:40
Rev12 pre-optimisation Superseded case retained for the audit trail.	Archived	197,340	+6.9%	$419.7M	Priya Nair	02 Jun 2026, 08:15

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Baseline against the two design options

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