In its 2016-2035 National Development Strategy, the Government of the Solomon Islands recognized the need for improved infrastructure, particularly upgrading and better maintaining the road transport network.<sup>25</sup> While most of the country's roads are low-volume, they nevertheless provide key benefits to the citizenry by way of access to health care, education, employment, markets, and leisure, as well as by reducing the costs of transit and trade. For roads, specifically, the conventional choice of paving in Pacific Island States has been some version of flexible pavement, such as bituminous surface coating (BTC / "chipseal") or asphalt. While these surface pavements generally perform well, they require routine maintenance, which is often lacking in Pacific Island countries. Concrete, on the other hand, while more costly with respect to initial construction, is also more robust and can yield lower whole-life costs due to reduced maintenance and repair.<sup>26</sup> While much of the road network needs upgrading to improve surface quality (including paving a portion of the unsealed network), there is also a pressing need to increase the network's resistance to extreme weather and geological events and the effects of climate change. Improving road segments' capacities to withstand natural hazards such as rising sea level and flooding, for example, may require such measures as the use of concrete pavements for vulnerable sections of road. Concrete pavements have the potential to improve resilience over the lifetime of a road asset and may even prove cost effective due to increased ability to avoid catastrophic damage, but they have hardly been used in the Pacific Islands. Similarly, vulnerable unpaved sections that may be washed out during heavy rainfall may be made resistant to higher levels of impact with paving. But such measures come at an increased short-term construction cost. Within this context, this study aims to estimate resilience gains derived from a set of road-upgrading alternatives for a case study road – the East Road of Malaita – and the comparative costs of upgrading. This test case will both inform decision-making for the East Road and serve as an empirical test of efforts to incorporate resilience considerations in infrastructure project design and selection.

# Malaita Road Network

Malaita is one of largest of the Solomon Islands, with an estimated population of 170,883 (according to 2012/13 HIES). The three primary roads of Malaita, namely the North Road (112.2 km), South Road (75.6 km) and East Road (41.7 km), together constitute nearly 60% of the road network on the island and carry the majority of vehicular traffic (Figure 1). These roads connect 19 of the 33 wards and provide access to 70% of the population.

Generally, however, conditions of the road network are poor, and many of the island's bridges are significantly deteriorated or structurally compromised.<sup>27</sup> Moreover, only 4% of the province's roads are sealed. While some of the sealed segments are short sections in Auki town, most are located along the North and South roads.<sup>28</sup> Only a reported 17.4 km of these main roads are sealed, and the remainder are unsealed coral gravel. Therefore, most of the road network is unsealed, poorly drained, and easily eroded.<sup>29</sup>

> 25 - - Solomon Islands National Development Strategy, 2016-2035. https://www.adb.org/sites/default/files/linked <u>documents/cobp sol-2017-2019-ld-01.pdf</u>

> 26 Johnson, S. and Visser, A. (2018). Viability of concrete pavements for low-volume roads in Pacific Islands Countries. 21 August 2018. Unpublished report, World Bank.

> 27 Only 23% of Malaita's bridges are concrete or steel bridges, compared with 40% in Western and Guadalcanal provinces and 62% for the Capital Territory of Honiara (World Bank, 2019).

> 28 These include the first 7.6 km of the North Road, the first 1.5 km of the South Road and an additional 1.9 km section near Bina, and the 2.8 km road linking to the airport.

> 29 Johnson, Sam William, Asif Faiz, and Alex Theo Visser. 2019. "Concrete Pavements for Climate Resilient Low-Volume Roads in Pacific Island Countries." The World Bank. <u>http://documents.worldbank.org/curated/en/537681568381365403/ConcretePavements-for-Climate-Resilient-Low-Volume-Roads-in-Pacific-Island-Countries.</u>

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