In 1825, one of Singapore's first colonial administrators, John Crawfurd, climbed the hill. He said that the surrounding forest was so dense that sailing to Calcutta was almost as easy as reaching Bukit Timah. In 1843, the access road to the summit was built. 40 years later, BTNR became the first forest reserve in Singapore to be conserved. The reserve has been protected by law since 1939, when the reserve was threatened by nearby granite quarrying at Hindhede Quarry. Till the late 1980s, BTNR was still part of the CCNR. Then, the government decided to build the BKE through the CCNR, thus splitting the CCNR and forming the BTNR. In 1991, the newly formed NParks, which manage Singapore's parks, nature reserves, and roadside trees, conducted a visitor survey. After gathering all the feedback, they began to develop facilities to improve visitors' experience at the reserve. and at the same time, reduce the damage that visitors might cause to the reserve. Over time, trails started to penetrate parts of the forest which were richer in biodiversity, causing plant and animal numbers to decrease. The ground surface was also damaged and soil erosion occurred. As a result, those trails were closed, and the main trails were upgraded.