Source: OECD.
Transport infrastructure investment and maintenance spending represent a relatively constant share of the GDP among a sample of countries, around 0.5% to 1% of GDP. Outliers, such as China and India, are facing strong economic growth and, more importantly, improving the performance of their transport systems. A lower share of investment relative to GDP is not necessarily indicative of capacity or performance issues, but the existing infrastructure level appears adequate to meet demands. Therefore, each transport system must be looked upon through the lenses of the existing level of accumulation and relation to existing and expected demand, including the lifespan of its existing infrastructure base.