BERLIN, Sept. 7 (Xinhua) -- Deutsche Bahn, Germany′s national railway company, has not been able to improve the punctuality of its long-distance trains, the German news agency dpa reported on Friday.

According to Deutsche Bahn sources, with about 30 percent of all long-distance trained being delayed, this is the worst August for punctuality since 2015. Deutsche Bahn management and CEO Richard Lutz have reacted to the bad numbers in an internal letter, asking for a better coordination between the company's business units.

In the letter, the Deutsche Bahn management board announces to decisively address the issue of poor punctuality. "We owe this not only to our customers, but also to our employees."

Deutsche Bahn defines a train as on time, if it is reaching its destination no later than six minutes after the planned time. "The prolonged hot spell in August led to more disruptions to carriages and infrastructure," the German railway company explained the frequent delays.

The 2017 European Railway Performance Index (RPI) by Boston Consulting Group, ranks German trains at forth rank after Switzerland, Denmark and Finland but the RPI report considers additional factors such as passenger safety and quality of service. According to the report, many of Europe's large railway networks, including Germany's, are struggling to maintain their RPI ratings.

Short and medium-distance train travel in Germany has a punctuality rate of 94.3 percent and has even slightly improved by 0.2 percentage points in August, partly due to the improving punctuality of city trams.

Deutsche Bahn had abandoned their original target of 82 percent punctuality for long-distance trains back in July and is now expecting to improve the rate from about 70 percent to 80. "We expect a trend reversal for the better in the second half of the year," CEO Lutz said when presenting the half-year results.