The West of Scotland list MSP who lives in East Dunbartonshire, said the latest statistics show that despite the decrease in numbers of both trains and passengers, only 49% of services arrived into Milngavie on time in the past 12 months.
According to Mr Greer, Scotrail’s monthly statistics have shown an improvement in performance across the rail network, but many lines, including the Milngavie line running through Bearsden are still showing significant problems.
He said: “A significant reduction in both the frequency of trains and the number of passengers should have resulted in an improved overall performance, given congestion on the lines is much less of a problem.
"These statistics show just how deep the problems with our rail network are though. Scotrail staff have done an incredible job during the pandemic but the network clearly needs much more investment, including on the Milngavie line.
“Having Scotrail brought back into public ownership will help. We need to go further though and build a modern, zero carbon rail system, like the Scottish Greens proposed in our Rail for All plan.
"That means upgrades to local rail services like to Milngavie, redualling the line.”
In response, a ScotRail spokesperson said: “In these extremely testing times, we are recording outstanding, and sustained, high levels of punctuality.
"We know that a dependable service is a top priority for customers who rely on our services through the pandemic.
“It’s a tribute to the hard work and dedication of ScotRail staff and Network Rail colleagues and we are determined to continue to deliver in order to make the railway the best public transport option available when the coronavirus pandemic is behind us and more normal times return.”
In January this year, Scotrail scrapped its service from Milngavie to Central Station during the day.
The company also reduced the number of trains on the Milngavie line from four an hour to two an hour, which it said was “temporary” because of the covid pandemic.