IN A CROWDED city like Hong Kong, skyscrapers seem to be the easy solution. But they are not foolproof. In line with this year's theme City Charm, the Joint School Science Exhibition (JSSE) provides clues which could lead to improvements in high-rise buildings. Participants have used their scientific knowledge and creativity to spruce up cities as they turn on the charm for the visitors. Rush To Heaven by SKH Lam Kau Mow Secondary School focuses on elevators and how to reduce their travel time. Unlike the traditional lift, the new version has no rails or cables. It is driven by a magnetic field, with electricity being supplied by columns located at the four corners of the compartment. 'Since there are no rails in our design, the friction between the lift and the surrounding area is largely reduced. So we can get to our destination in a shorter period of time,' explained project leader Patrick Fung Hok-kin. 'Also, the ride is quieter since no motors are used.' While one team was thinking of a quicker way to carry people up and down inside a building, another group of students invented a locomotion system for the outer wall of a skyscraper. 'In movies such as Spider-Man, we often see someone moving freely on a wall. So we designed Wall 'n' Roll to make the idea a reality,' said Jacky Fung Chi-ching, who led the team from Chan Sui Ki (La Salle) College. Wall 'n' Roll is a carriage which resembles a tank. Based on the design of suckers and moving systems used by tanks, the device can move on vertical surfaces. 'It will be safe and convenient for the workers to do the cleaning and the maintenance of the outer walls,' Jacky added. The above two inventions help people to reach the top of a high-rise building, while Clear Rescue will ensure their safety from a fire. Hoi Ping Chamber of Commerce Secondary School's project is aimed at reducing injuries and loss of life during a fire. In the design, there is a roof-top gondola which can be used by residents trapped on the upper floors of a building that rescuers cannot reach. The exhibition at the Hong Kong Science Museum ends on August 20. Admission is free.