Bus fares from journeys

The model prices supplied person-level local-bus journeys from 2024 onwards. person_bus_fare_spending sums London and other-local-bus spending; bus_fare_spending sums it across household members. These outputs describe spending. transport_consumption already includes bus spending, so consumers must not add it to the consumption total again. This implementation does not change transport consumption, disposable income or government subsidy totals.

Inputs and fallback¶

The Microcosm nts_bus_travel stage supplies bus_in_london_trips, other_local_bus_trips, their sum local_bus_trips, bus_pass_eligible and local_bus_single_fare_share at Person level. Trips are annual quantities. A supplied zero counts as journey data. A cached default does not. If only local_bus_trips is supplied, London residents’ trips use the London series and other residents’ trips use the other-local-bus series. When either split series is supplied, that split takes precedence and the absent series is zero. Supply consistent splits for cross-boundary travel.

The model treats a person flagged bus_pass_eligible as travelling free, matching Microcosm’s pricing assumption. The dataset owns that eligibility flag; the model does not infer concessionary eligibility from age or change it when a concessionary scheme is reformed. Supply bus_pass_eligible alongside journey inputs, including in household calculators; an omitted flag defaults to false and the person pays fares even if eligible for a statutory concession. For fare-paying passengers, local_bus_single_fare_share is the share of boardings bought as singles, bounded to [0, 1]. Its fallback is 0.70, the 2024 NTS other-local-bus estimate. An optional local_bus_uncapped_single_fare replaces the table of uncapped single fares described below for that person. Negative quantities and fares price at zero.

On loading a UK Simulation, a supplied household bus_fare_spending moves to bus_fare_spending_reported. The stored total therefore cannot freeze the journey formula in a reform. Without journey inputs, the model retains this reported total and allocates it using fare_allocation_weight_by_age. Reported totals retain CPI uprating. Wales and unknown regions retain the reported total even when journey inputs exist, following Microcosm’s decision to leave areas without published receipts unpriced. Before 2024 the model also uses this legacy route. Direct core/YAML tests can still override the household output explicitly.

Published price benchmark¶

The model uses FY2024–25 published facts. For each area, receipts R, boardings B, concessionary boardings C, annual trips per resident T and population P give:

• Yield per priced boarding: y = R / (B - C).

• Boardings per resident trip: k = B / (T * P).

Sources: DfT BUS01 and BUS05i, NTS0705a, Scottish Transport Statistics 2025, tables 2.2a and 2.8, NI Public Transport Statistics 2024–25, figures 3, 4 and 6, and Microcosm’s fact extraction and pricing implementation. Population denominators use ONS mid-2024 estimates. London uses all English residents because non-residents also travel there. Scotland and Northern Ireland use the English other-local-bus trip rate as a proxy, as Microcosm does. These translations include interchanges and differences between operator boardings and resident trips; they are not counts of legs for a known trip. gov.dft.bus.benchmark_year (2024) names the fiscal year these facts describe.

Outside London, C uses BUS01c’s older-and-disabled concessionary journeys. The other concessions remain in the priced denominator, so the yield absorbs their discounts. BUS01c’s total would also remove 116.3 million youth-scheme journeys (BUS01c note 4) that the dataset’s bus_pass_eligible flag does not generally make free. The older-and-disabled count approximates that flag: Microcosm flags older-person eligibility and under-5s outside London, but does not flag disabled pass holders. London uses total concessionary journeys; Scotland and Northern Ireland retain their own counts.

Charging disabled pass holders raises modelled spending; making under-5s free lowers it. Microcosm issue 1385 reports that this denominator change moves outside-London fares from 6.8% above BUS05ai to about 1.8% below it on the certified build microcosm-uk-2024-25-national-20261019T083323Z-6cba5d71, using its existing weights and model year 2024.

Microcosm’s fact selectors and model lock must use the same concessionary definition as this benchmark. The companion update follows the model release and is tracked in Microcosm issue 1385.

Fares by year¶

In other years each area’s yield moves with its published fares index:

yield(t) = benchmark_yield * index(t) / index(benchmark_year)

gov.dft.bus.local_bus_fares_index holds DfT’s BUS0415a quarter-end values (March 2005 = 100) for London, England outside London and Scotland, from DfT’s June 2026 release (quarters to March 2026; archived copy), the vintage Chronicle and Microcosm vendor. DfT’s September 2026 release, now served at the same address, revises the last two quarters and adds June 2026; move to it together with Microcosm. Each value is dated at the start of the quarter it ends, and fiscal_year_blend day-weights the quarters over 6 April to 5 April, the model’s year. FY2024–25 outside London is therefore (86 × 181.6 + 92 × 185.7 + 92 × 185.9 + 90 × 206.4 + 5 × 210.5) / 365 = 190.23, within 0.2% of the mean of its four quarter ends (189.9). After the last published quarter the index grows with the OBR consumer price index each January, as private_rent_index does. Northern Ireland has no published index, so its yield grows with CPI from the benchmark year. Wales stays unpriced.

The CPI projection also raises the fares in the index that the £3 cap holds at £3, while the cap term below measures changes from a nominal £3. From January 2027 a ticket held at a cap therefore costs about £3 times the CPI growth since March 2026 more than the cap allows. That overstates the outside-London yield by 0.4% in 2027–28 and 0.7% in 2028–29, about 0.3 points more each year after. A cap reform is measured against the same reference as the baseline, so its cost does not move.

FY2025–26 and earlier are published; later years are CPI projections. The index records prices paid, so it already contains each cap in force while it is published, including the rise to £3 in January 2025 (outside London 185.9 in December 2024, 206.4 in March 2025). The cap term below adds only what the index cannot contain.

Each area follows its own index, so the England total moves with the receipts-weighted mix of the London and outside-London indices: +7.6% in FY2025–26. DfT’s England index rose 6.4%. Its step from December 2024 to March 2025 was 5.6%, against 11.0% outside London and none in London, so it weights outside London at about one half, where receipts weight it at 61%. A receipts target moved by the England index therefore sits below the model’s England total.

Caps and the uncapped counterfactual¶

gov.dft.bus.fares.cap records the national cap on participating single-ticket services in England outside London: £2 from January 2023, £3 from January 2025, and £2 from January through December 2027. After December 2027 it is infinite, representing the end of the announced scheme. These dates follow the DfT evaluation, £3 scheme guidance and 2027 announcement. The cap does not affect the London series, Scottish or Northern Irish fares. England outside London uses a representative participating-service assumption; route-level participation and local lower caps require caller-supplied fares. The table of uncapped fares below is fitted to national figures and applied the same way in every English region outside London. Where a combined authority already runs its own lower single fare, a national cap reform therefore overstates the savings, and elsewhere it understates them. National totals hold, but regional and distributional splits of a cap reform lean the wrong way.

The published yield and index already include ticket discounts and the cap in force. gov.dft.bus.reference_fares.cap records that cap: the cap in force up to the last published quarter of the index (£3 from January 2025), held after it. For an English fare-paying person’s other-local-bus boardings, the model uses:

yield(t) = max(0, benchmark_yield * index(t) / index(benchmark_year)
                  + single_share * sum over bands b of share_b *
                    (annual_min(fare_b, fares.cap, t) -
                     annual_min(fare_b, reference_fares.cap, t)))
spending = trips * boardings_per_trip * yield(t)

Both schedules are read in the same year. While the index is published they agree and the cap term is zero, so the baseline is the published path. After the last published quarter the term adds the scheduled changes: the £2 cap from January 2027 and its end in 2028. A reform of fares.cap adds its own difference from the reference. Leave reference_fares unchanged in reforms. When a newly published quarter is added to the index, extend reference_fares.cap with the cap then in force; policyengine_uk/tests/test_bus_fare_parameters.py fails until the two schedules agree up to the last published quarter.

annual_min caps the fare in each date interval, then weights the intervals from 6 April to 5 April, assuming uniform journeys through the year. It does not cap a fare using the average cap. Both fares and reference_fares keep calendar dates (their index files propagate preserve_calendar_dates to the cap leaves), so a cap change part-way through a year applies from its date. The source receipts use 1 April to 31 March; this approximation treats them as the corresponding model year’s benchmark. Annual Scenario changes apply to the full model fiscal year.

Uncapped single fares¶

What a cap saves depends on how uncapped single fares are spread, not on their average. gov.dft.bus.uncapped_single_fares holds three bands, each with its share of single tickets and its mean uncapped fare at FY2024–25 prices:

The fares rise with the OBR CPI after FY2024–25 and the shares stay, so a fixed cap saves more as fares rise. The model caps each band’s mean fare under both schedules and weights the bands by their shares, which must sum to one. With the bands at their means, the table is exact for caps of £2 and £3 at FY2024–25 prices and approximate for other caps; a cap below the low band’s mean needs more bands.

scripts/fit_bus_cap_savings.py fits the table by least squares to the facts below, each scaled by its tolerance. It searches shares in steps of one point and fares in steps of one penny, keeps each band’s mean at least 10% above its lower edge, and sets the low band’s fare so all singles average £2.15. The last column is each fact under the fitted table, on the OBR’s October 2026 CPI path:

The £400 million is read as £2 against no cap: the £3 scheme is funded only to December 2026, and the £2 scheme replaces it. Read as £2 against a continued £3 cap, the table gives £268.7m, 33% below. The script prints both.

The 2024–25 grant, for the benchmark year itself, is reported and not fitted; the table puts it at about half. Grant per priced boarding rose 77.5% on 2023–24, while the outside-London index rose 6.7%, receipts per priced boarding rose 2.6%, and the cap rose only for the last quarter. The figure may therefore hold more than that year’s forgone fares (timing or coverage of payments, not checked). The 2023–24 grant and the two announced figures all put a full year at £2 near £0.3bn, not £0.6bn. The single £2.748 fare this table replaced was calibrated to the 2024–25 grant.

The costs use the 0.70 default single share and priced boardings outside London (BUS01a journeys less BUS01c older-and-disabled concessionary journeys: 1,390m in 2023–24 and 1,448m in 2024–25, which also stands for 2025 and 2027), with fares moved to each year by CPI. Table 6 compares January to October 2022 with the same months of 2023 and is read at face value, for the table’s shape. Deflated to 2022 prices it would put the 2023–24 saving about 40% above the grant. Possible reasons, not checked, are that the grant pays operators for revenue lost net of the journeys the cap added, and that Table 6 covers the larger participating operators only. The two announced figures are budgets; the £2 cap’s first ten months paid £210m against £245m planned. The table is a fitted central estimate, not an observed fare distribution.

At FY2025–26 prices the table saves £0.36 per single ticket for a full year at £2 against no cap, and £0.14 at £3: about £0.36bn and £0.14bn a year at 2024–25 boardings.

A dataset or calculator can supply local_bus_uncapped_single_fare for each person. Where it is supplied, that person’s single tickets cost that one fare before the cap, and the table is not used. Single-year datasets extended by Simulation uprate it with CPI. Very large reductions can reach the zero-yield floor.

Other reform controls and limits¶

fare_index / prior_law_fare_index multiplies both journey-priced and legacy spending. Both default to one; they are neutral reform controls rather than historical index series. Keep the denominator positive. ridership_index defaults to one and multiplies journey-priced spending, leaving supplied journey inputs intact. The model includes no demand elasticity or automatic ridership growth. Trip translations stay constant after 2024 unless changed explicitly; yields move with the fares index. Dataset CPI-uprated household bus totals do not determine prices where journeys are available.

A proportional scenario can set gov.dft.bus.fare_index to 0.9 for a 10% reduction. A cap scenario changes gov.dft.bus.fares.cap; leave the reference schedule and benchmark yield unchanged. Set the cap to infinity to remove it. The fixture-scale tests exercise both routes through UK dataset loading and Scenario, including baseline isolation and the January cap transitions.