Do Roads Pay Off? Measuring Infrastructure's Impact

How economists measure whether infrastructure spending pays off, with evidence from India's Golden Quadrilateral and rural roads programme.

Governments spend huge sums on infrastructure. Does it pay off? Economists use several methods to find out.

Cost-benefit analysis

Before building, planners estimate costs and benefits over the project’s life, including:

Time saved by travellers.
Lower vehicle operating costs.
Fewer accidents.
Wider economic benefits, such as new businesses.

Future values are discounted to compare with today’s costs. A project is worthwhile if benefits exceed costs.

Evidence from the Golden Quadrilateral

The Golden Quadrilateral, a highway network connecting Delhi, Mumbai, Chennai and Kolkata, was upgraded in the late 1990s and 2000s.

Economists Ejaz Ghani, Arti Grover Goswami and William Kerr studied its effects and found that manufacturing activity grew substantially in districts near the highway, including more new businesses and higher output, compared with districts further away.

Evidence from rural roads

The Pradhan Mantri Gram Sadak Yojana, launched in 2000, built all-weather roads to connect villages.

Research by economists Sam Asher and Paul Novosad found that new rural roads helped workers move out of agriculture into other jobs, though effects on farm incomes and consumption were smaller than some expected. Other studies found benefits for school enrolment and access to markets.

Why measurement is hard

Where roads go isn’t random: they may be built where growth was already expected.
Displacement: new activity near a road may come from elsewhere.
Long time frames: benefits may take years.

Economists use methods like comparing places that got roads because of arbitrary rules, such as population thresholds, to isolate effects.

Module recap

Infrastructure has high sunk costs, long lives and big spillovers.
PPPs, HAM, tolls, InvITs and asset monetisation shape financing.
Land acquisition, delays and overruns are key challenges.
Airports, Jal Jeevan Mission and BharatNet show different sectors in action.
Evidence shows infrastructure can boost growth, though effects vary.

The highway effect

A district on the Golden Quadrilateral sees new factories set up after the highway upgrade, as firms can now ship goods quickly to big cities. A similar district far from the highway sees little change.

Thinking all infrastructure automatically boosts growth

Benefits depend on location, design, complementary policies and maintenance. Some projects deliver less than promised.

Key takeaways

Cost-benefit analysis compares discounted benefits and costs.
The Golden Quadrilateral boosted manufacturing in nearby districts.
Rural roads helped workers move out of agriculture.
Measuring impacts is hard because road placement isn't random.