Lesson 2 of 4 Math checked Facts checked against sources on 16 June 2026 14 min

Transport infrastructure economics: regulated returns, traffic risk and concessions

Why margins are high but returns are modest, how a regulator builds a charge, how a concession is valued, and the difference between traffic risk and availability payments.

Industry brief, with a one-minute summary: Transport infrastructure

Key takeaways

Transport assets keep a large share of revenue as EBITDA, often 55 to 85 percent, because most of their cost is the asset itself, which shows up as depreciation and interest rather than running costs.
Transurban says more than 90 percent of its revenue comes with tolls that rise each year with inflation or by fixed steps, and its roads had a weighted average of 27.3 years of concession left in 2026.
Where an airport or port has market power, a regulator caps what it may charge, usually for five years at a time.

Key idea

Transport assets keep a large share of revenue as EBITDA, often 55 to 85 percent, because most of their cost is the asset itself, which shows up as depreciation and interest rather than running costs. That does not make them hugely profitable on the money invested: regulators and concession contracts are designed to give a steady, modest return on a very large asset. The money is made or lost on three things: the allowed return or toll formula, the traffic, and building the asset on time and on budget.

EBITDA margin of some transport infrastructure owners, latest full year (percent of revenue)(%)

So-what

Toll roads keep the most, because a road has few staff per vehicle. Airports need terminals, security and baggage staff, so they keep less. Port groups that add trucking and logistics, such as DP World (26.3 percent in 2025), keep much less than a pure terminal.

How a regulator sets a charge: the building blocks

Where an airport or port has market power, a regulator caps what it may charge, usually for five years at a time. The regulator adds up the revenue the owner needs: a return on the regulated asset base (the asset base times the allowed return, often called the weighted average cost of capital, or WACC), depreciation to pay back the assets over their lives, and efficient running costs. It then divides by forecast traffic to get a charge per passenger. For Heathrow's 2022 to 2026 period (called H7), the UK Civil Aviation Authority allowed a real return of 3.18 percent. For 2027 to 2031 (H8) its first proposals, in March 2026, were a cap of GBP 27.20 to GBP 30.50 per passenger in 2024 prices, against an average of GBP 28.40 over H7. In Spain, the government approved Aena's 2027 to 2031 plan in September 2026 with an allowed pre-tax return of 8.32 percent and charges rising by 0.33 percent a year, after Aena had asked for 3.82 percent a year.

Worked case

Setting a regulated airport charge: single till or dual till?

The prompt

A regulator in the UK is setting the charge per passenger at Harbourfield Airport (fictional) for the next five years. The airport's regulated asset base is GBP 10,000 million and the allowed return is 5 percent a year. Depreciation is GBP 400 million a year and operating costs GBP 1,100 million. Shops, parking and property earn GBP 800 million a year. The forecast is 60 million passengers a year. What charge per passenger follows if shop income counts (single till), and what if the airport side alone needs GBP 1,650 million (dual till)? What if only 50 million passengers come?

Open this case to practice it with a partner

The structure

Charge per passenger = revenue the airport is allowed, minus what the till counts, divided by passengers
- Allowed revenue = return on the asset base + depreciation + operating costs
- Which income offsets it: single till (all income) or dual till (airport side only)
- Divide by the passenger forecast
- Traffic risk: who pays if fewer passengers come

Working it through

1. Return on the asset base
5 percent of GBP 10,000 million.
Allowed return (GBP million):10,000 × 0.05 = 500
2. Allowed revenue
Return plus depreciation plus operating costs.
Allowed revenue (GBP million):500 + 400 + 1,100 = 2,000
3. Charge under a single till
Shop and parking income of GBP 800 million is taken off first.
Charge per passenger, single till (GBP):(2,000 - 800) ÷ 60 = 20
4. Charge under a dual till
The airport side alone needs GBP 1,650 million, and the airport keeps its shop profit.
Charge per passenger, dual till (GBP):1,650 ÷ 60 = 27.5
5. Shortfall if traffic falls
Under a single till at GBP 20, 10 million fewer passengers means less charge income.
Yearly shortfall at 50 million passengers (GBP million):(60 - 50) × 20 = 200

The recommendation

The regulator should set the charge at about GBP 20 per passenger under a single till, because shop and parking income exists only because airlines bring passengers, and counting it cuts the charge from GBP 27.50 to GBP 20. First, the GBP 2,000 million of allowed revenue still covers a 5 percent return, depreciation and costs, so investors are paid for the assets. Second, a lower charge helps keep airlines and routes at the airport. The risk is traffic: if only 50 million passengers come, the airport is GBP 200 million short each year, so the rules must say who bears it. As a next step, add a traffic band that shares gains and losses between the airport and its users, and test the charge against a low passenger forecast.

Risks: A single till weakens the airport's reason to grow shop income; A shock such as a pandemic or closed airspace can break any five-year settlement.

Timed math drill

Heathrow's regulated asset base was GBP 21,263 million at the end of 2025. As a rough guide, what does a 3.18 percent real return on that base come to in a year, in GBP million? (Round to the nearest million.)

Concessions: who carries the traffic risk

A concession gives a private company the right to build or run an asset for a fixed time in return for the income it earns. With a user-paid concession (a toll road, a port terminal), the company carries the traffic risk: if fewer vehicles come, it earns less. With an availability payment, the government pays a fixed sum as long as the asset is open and in good condition, so the company carries mostly building and upkeep risk. India uses both. Under toll, operate and transfer (TOT), investors pay the National Highways Authority of India a lump sum up front for the right to collect tolls for 15 to 30 years; INR 58,265 crore had been raised this way by November 2025. Under the hybrid annuity model, the government pays 40 percent of the project cost during construction and the rest as 30 half-yearly payments after the road opens, so the builder carries no traffic risk.

Worked case

How much to bid for a toll road concession in India

The prompt

An infrastructure fund is bidding for a 20-year toll, operate and transfer concession on a highway in India, paying the government a lump sum up front. The road carries 40,000 vehicles a day at an average toll of INR 150. Operations and maintenance cost INR 55 crore a year and barely change with traffic. The fund wants its money back within 8 years. Is a bid of INR 1,200 crore safe, and what if traffic is 25 percent below forecast?

Open this case to practice it with a partner

The structure

Is the bid paid back in time = yearly cash from tolls minus costs, against the price paid
- Toll revenue = vehicles per day x average toll x 365
- Cash after operations and maintenance, which are mostly fixed
- Payback = bid divided by yearly cash
- Traffic risk: the low case

Working it through

1. Yearly toll revenue
40,000 vehicles x INR 150 x 365 days, in crore (1 crore is 10 million).
Toll revenue (INR crore):40,000 × 150 × 365 ÷ 10,000,000 = 219
2. Cash after operations
Take off INR 55 crore of operations and maintenance.
Yearly cash before tax and financing (INR crore):219 - 55 = 164
3. Payback at forecast traffic
INR 1,200 crore divided by INR 164 crore a year.
Payback, forecast traffic (years):1,200 ÷ 164 = 7.32
4. Revenue if traffic is 25 percent lower
30,000 vehicles a day at the same toll.
Toll revenue, low case (INR crore):30,000 × 150 × 365 ÷ 10,000,000 = 164
5. Payback in the low case
Costs stay at INR 55 crore, so yearly cash falls to INR 109.25 crore.
Payback, low traffic (years):1,200 ÷ (164.25 - 55) = 10.98

The recommendation

The fund should bid no more than about INR 1,200 crore, and only if it is comfortable with the low case, because the bid pays back in about 7.3 years at forecast traffic but in about 11 years if traffic is 25 percent lower, past its 8-year target. First, costs are mostly fixed, so a 25 percent fall in traffic cuts yearly cash by a third, from INR 164 crore to about INR 109 crore. Second, the fund carries all the traffic risk under this model, unlike a hybrid annuity road where the government pays. The risk is that a new parallel road or a change in toll rules cuts traffic for years. As a next step, check traffic counts at the toll plazas, planned roads nearby and the toll increase formula before setting the final bid.

Risks: A new free road or rail line can take traffic; Toll increases follow a formula linked to inflation, which may lag costs.

Why toll roads are prized by long-term investors

Transurban says more than 90 percent of its revenue comes with tolls that rise each year with inflation or by fixed steps, and its roads had a weighted average of 27.3 years of concession left in 2026. Pension funds and insurers like income that rises with prices and lasts decades. The catch is that the value depends on traffic forecasts made decades ahead, and on the contract: VINCI's main French motorway concessions, which earned VINCI Autoroutes a 71 percent EBITDA margin in 2025, end between 2032 and 2036, and France is still deciding what replaces them.

Timed math drill

A road in India is built under the hybrid annuity model, with a bid project cost of INR 2,000 crore. The government pays 40 percent during construction in 10 equal parts. How much is each part, in INR crore?

Check your understanding

Two highway contracts have the same cost and length. In one the operator keeps the tolls; in the other the government pays a fixed sum each year if the road is open. Which should an investor value more highly, all else equal, and why?

Terms in this lesson

Rate base Cost of capital (WACC)Depreciation and amortization EBITDA Payback period Net present value (NPV)Sensitivity analysis Public-private partnership (PPP)Availability payment Fixed cost

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It builds on what you just read, in Transport infrastructure: airports, seaports, toll roads and rail.

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