Average network speed ; calculated as total passenger kilometres divided by total passenger hours . the cost of road - based freight transport ; the cost of charges and operating costs as a percentage of gdp . the computer aided sustainability evaluation tool ( caset ) 交通网平均速度;即各公共及私营的主要交通工具的平均行车速度,反映出乘客乘搭交通工具时的平均车速(以乘客行程总距离[公里]除以乘客行程时间[小时]计算) 。