Technical Report Draft 1: Flood Reduction with Sustainable Porous Asphalt

1. Introduction

1.1. Background Information

Porous asphalt is a type of asphalt that allows water to permeate through its surface into a collection pond underlying soil below the pavement. This is made possible by controlling and/or changing the amount of materials used in conventional asphalt mixes, such as the fine and coarse aggregates, along with some variations in construction methods to produce the desired outcome of reducing surface runoff. Porous asphalt has the capacity to conserve water, reduce runoff and promote infiltration which cleanses stormwater, all of which are acquired from the relatively high porosity and permeability of the porous pavement layers. Due to its unique functional benefits, porous asphalt has thus been used for many years worldwide as an effective means of stormwater management.

1.2. Problem Statement

The rainfall recorded in Singapore has been steadily rising over the years (Fig 1.) (Meteorological Service Singapore, 2018). This increase in frequency and intensity of rain, in conjunction with the increase in the car population in Singapore, is a catalyst for road accidents as wet road conditions reduces the friction car tyres have against the road surface. This in turn leads to higher chances of skidding and accidents as motorists lose control of their vehicles. When the road surface allows for water seepage, it reduces ponding and will therefore provide motorists a safer and pleasant driving experience. However, there is a relatively large initial cost and work required to replace existing asphalt surfaces with its porous variant (Fig 2). Highlighting the advantages porous asphalt would contribute toward sustainability, such as introducing recycled by-products in the production process as well as providing non-potable use for the water collected from the asphalt, might greatly encourage transport engineers to consider porous asphalt as an alternative to the conventional road mix.

1.3. Purpose Statement

The purpose of this report is to propose the implementation of porous asphalt on busy roads to reduce the occurrence of floods in areas such as the Central Business District. The proposed methodologies and application of porous asphalt roads would demonstrate to Land Transport Authority (LTA) that porous asphalt not only mitigates the occurrence of floods, it can also be presented as a sustainable approach to mitigate road flooding.