developed countries<sup>11</sup> and assumed linearly related to daily GDP per capita. It is likely that those estimates are overestimated due to the wealth effect and the fact that WTP usually decreases with the reliability of the water distribution system (Hensher et al., 2005). Second, the countries included in the ES correspond to the middle of the global GDP distribution: the 123 countries cover 49% of the global GDP, preventing an accurate extrapolation of the global total annual cost of water outages for households. Third, the ES reports water outages experienced by firms and not households. Depending on the country’s regulation, households or firms may be served following an order of priority in case of a water supply disruption what would suggest that they do not experience the same outages.

# 3. The impact of transport disruptions

## 3.1. Transport disruption and congestion affect all cities

Road congestion is a growing issue in cities. INRIX, a transport-data company found that a driver spent on average 36 hours in gridlock in 2013 in French, British, German and American metropolitan areas (Cebr, 2014a). The time lost to congestion increases threefold to 111 hours when additional planning time is included.<sup>12</sup> The study used GPS data from some 300 millions of cars and devices to measure when and where traffic slowed to a crawl along 5 million miles of roads, spanning 1,360 cities in 38 countries.<sup>13</sup> Capital cities in developing countries suffer the most from traffic because roads and public-transit systems have not kept pace with population growth. In Thailand, drivers loose an average of 56 hours a year to congestion at peak travel times; Indonesia and Colombia come second and third with 51 and 49 hours. Similarly, the worst place to drive in Europe is Russia, which accounts for five of the continent’s ten most congested cities.

Weather events have an adverse effect on travel time for households by affecting driving abilities and contribute to congestion. A literature review of existing evidence from the US and the UK on the impacts of weather conditions on travel time finds that travel time delays increase by 11% in wet conditions and by more than 12% in the presence of precipitation, high winds, low visibility or slick pavement (Goodwin, 2002). Flows of traffic can be reduced by between 6% and 30% depending on road conditions and time of day. In rainy and wet conditions, speed reduction ranges from 10% to 25% in the reviewed studies.

Urban flooding is a major cause of transport disruptions in cities across the world. For instance, in inner Kampala, Uganda, 11% of primary roads are located directly in zones of high flood risk (11.8km out of 108.2km) (Figure 8). When floods do occur, vast parts of the urban road network are cut off. This illustrates that road users across the city will be affected by flooding, regardless of whether they are located in flood zones or not. This implies severe disruptions to the road network and, consequently, the operations of firms, the delivery of services, and the accessibility of jobs. A forthcoming study by the World Bank provides evidence from Dar es Salaam, Kampala, Bamako, and Kigali, and shows that infrastructure disruptions are by no means limited to certain low-income neighborhoods. While infrastructure disruptions indeed physically occur with increased frequency and intensity in certain hotspots, infrastructure systems are networks that transmit the disruptions due to urban flooding across wide areas. This is true both for the severe flooding which are relatively rare and the nuisance floods, very localized, disrupting traffic without stopping it, which is a daily issue in tropical cities and regular occurrence in most cities of emerging countries.

> 11 Australia and the US, see Table 7.

> 12 Planning time is the time lost due to uncertainty in travel speed, because drivers have to leave earlier to make sure they arrive on time (here, at least 95 percent of the time).

> 13 http://inrix.com/scorecard/

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