was limited to tremors felt in some of the common high-rise buildings there. Political and human geography When Singapore was first colonized by the British, the City of Singapore was situated on the southern coast, around the mouth of the Singapore River. This area remains the Central Area of Singapore. The rest of the island was farmland and primary rainforest. However, since the 1960s the government has constructed many new towns in other areas, so that today the island is nearly entirely built-up and urbanised, with only a few exceptions, such as the district of Lim Chu Kang or reclaimed land in the process of being developed. The country has several subdivisions, mostly used for administrative or statistical purposes. Politically, Singapore is divided into five administrative districts, these are then further subdivided into town councils which usually consists of one or more political constituencies. However, unlike other countries where local government subdivisions are used to cite locations, the same practice is often uncommon in Singapore. Political boundaries fluctuate with every general election and thus, the areas they cover do not necessarily correspond to the local perception of a place. Most geographical regions, districts and neighbourhoods within the city-state are usually overlapping and can sometimes be arbitrarily defined. Planning and census boundaries, called planning areas, have been used by the Urban Redevelopment Authority to define certain districts and neighbourhoods, although these boundaries may not necessarily correspond with the common perception of a certain place. While boundaries for new towns do exist, there have been instances where certain neighbourhoods can be identified separately from the town it is located in. Tiong Bahru for example, is often identified separately from the HDB town it is a part of, Bukit Merah. As the main government agency responsible for the urban planning of Singapore, the Urban Redevelopment Authority seeks to implement efficient land use and minimise pollution while maintaining convenient transport, which are Singapore's largest concerns because of its situation as a city-state. A Development Guide Plan for each of the 55 planning areas has been released in the process. In order to reduce traffic congestion, Electronic road pricing (ERP) has been enacted around entrances into the Central Area. The other parts of Singapore are less dense and busy, and are often filled with housing estates such as from the Housing and Development Board (HDB) or condominiums, and commercial districts are less concentrated. However, to