The Lewis-Mogridge Position was formulated in 1990. It captures the evidence that the more roads are built, the more traffic there is to fill these roads. Speed gains from new roads tend to disappear within months if not weeks. Sometimes new roads do help to reduce traffic jams, but in most cases the congestion is only shifted to another junction.
The position reads "traffic expands to meet the available road space" (Mogridge, 1990).
Following the Lewis-Mogridge Position it is not generally concluded that new roads are never justified, but that their development needs to consider the whole traffic system. This means understanding the movement of goods and people in detail, as well as the motivation behind the movement.
