Researchers from the mainland's top scientific institution have criticised some government officials' obsession with speed, calling for more resources to be allocated to the development of slower transportation. The construction of high-speed transport networks, such as expressways and high-speed railway lines, accounted for too much of infrastructure investment, the Chinese Academy of Sciences' Institute of Geographic Sciences and Natural Resources Research said in a report released in Beijing on Monday. In the meantime, low-speed networks such as paved village roads and ordinary railway lines were not maintained or left undeveloped. Professor Liu Weidong, an author of the report, said that only a small proportion of the country's 1.3 billion people - the rich - had benefited significantly from the frantic construction of high-speed transportation networks in recent years. Many expressways were seriously underused, serving only a handful of vehicles most of the time, he said. High-speed railway lines had more or less the same problem, with operations in financial difficulty due to insufficient passenger numbers. 'We don't oppose the construction of high-speed transportation but we will face a disaster if slow-speed transportation is ignored,' Liu said. According to the report, nearly 100 towns and more than 40,000 villages on the mainland lack road access. In 2009, dirt roads made up more than half of the mainland's road network and the situation has not changed much since, with little invested to rectify it in recent years. Most people, especially in rural areas, remained poorly connected and their living standards had been severely undermined, Liu said. The economy could not take off with so many struggling to catch up on roads made of dirt and rubble, he said. 'If you go to the western part of China and steer off the expressway, you will often run into roads more suitable for horses than vehicles,' he said. 'Many are poorly maintained, with cracks and holes everywhere, and there are no lane marks or safety signs at all.' Some officials were convinced that high-speed transportation was their shortcut to promotion, Liu said. 'They build expressways and high-speed rail lines as a political achievement,' he said. 'Senior officials and foreign guests are not often given tours of an isolated village.' Professor Zhao Jian, an economist at Beijing Jiaotong University, said that he agreed with the report but that it might actually be downplaying the problem. High-speed railway lines came with high ticket prices and high maintenance costs, he said. Zhao said high-speed rail worked in smaller countries like Japan and Germany, but in China, with its vast landmass, it would probably be strangled by poor economic returns. The mainland now has a longer expressway network than the US, but the US one is used by 300 million cars, compared with less than 80 million on the mainland. 'High speed comes with high costs,' Zhao said. 'We might be broke before we reach our destination.'