CHENNAI: If everything goes per plan, Chennai metro rail will open three stretches -airport to Saidapet, St Thomas Mount to Alandur and Koyambedu to Nehru Park via Anna Nagar -in August.Trial runs are expected to begin either by the end of this month or next month, an official said.The commissioning of the stretches will make more than 60% of the two-corridor, 45.1km network functional.All the lines were expected to be ready by the end of 2015, but deadlines were revised to the middle of this year. The project would take at least an other two years to be completed, taking the cost from `15,500 crore to `20,000 crore.Of the parts to be functional next, the Airport-Saidapet (10km) stretch and the St Thomas Mount-Alandur (1.5km) stretch are elevated, while the Koyambedu-Nehru Park line on Poonamallee High Road via Anna Nagar (8km) is underground. Officials of Chennai Metro Rail Ltd said they plan to start trials as electrification of the line is nearing completion.“We will be ready as planned.The state government will announce the inauguration date,“ an official said. Racing against time to open a few more met ro rail stretches ­ airport to Saidapet, St Thomas Mount to Alandur and Koyambedu to Nehru Park ­ by August this year, officials are get ting ready for trial runs.In October last year, they conducted a trial run from Little Mount to Nanganallur on airport line and Tiru mangalam to Anna Nagar Tower station to see if the tracks were fit for operation “The Tirumangalam-She noy Nagar underground stretch will be fully electri fied by the third week of this month. The Shenoy Nagar Nehru Park line will have electric overhead cables in place by May ,“he said.Work on the airport line is in progress though a 500m portion where the line goes below the surface near the airport was affected during the December flood. The airport station is expected to be ready as per the new dead line. An official said some in terior work at a few stations including St Thomas Mount, will take some more time. However, metro rail officials are concerned that elections may come in the way of commissioning the work. Commissioning of the elevated line from airport to Saidapet will be a boon for travellers who land at the airport. Those heading towards Koyambedu can get down at Alandur station for a change-over. The airport will get connected to Alandur, Guindy and Chennai Mofussil Bus Terminus at Koyambedu.Travel time from Anna Nagar to airport will be down from more than an hour during peak hour to less than half an hour by metro trains.