We estimate the marginal external congestion cost of motor-vehicle travel for Rome, Italy, using a methodology that accounts for hypercongestion (a situation where congestion decreases a road’s throughput). We show that the external cost – even when roads are not hypercongested...

We estimate the marginal external congestion cost of motor-vehicle travel for Rome, Italy, using a methodology that accounts for hypercongestion (a situation where congestion decreases a road's throughput). We show that the external cost - even when roads are not hypercongested - is substantial,...