THE number of overcrowded trains on the ScotRail network has more than quadrupled over the past five years amid record demand for rail travel.

The problem is most frequent on Glasgow-Edinburgh services during the morning and afternoon peak periods, which accounted for more than one-quarter of overcrowded trains.

However, the highest loadings were recorded on trains in the Strathclyde suburban network, which accounts for nearly two- thirds of train journeys in Scotland. On services between Dalmuir and Motherwell or Larkhall, some trains had in excess of 100 more passengers than seats available.

Figures disclosed by Transport Scotland show that on a typical week, passengers would have expected to stand for more than 10 minutes on 34 services last summer, compared with just eight in 2006.

The figures, based on passenger counts by ScotRail, come at a sensitive time for the Scottish Government, which has been forced to consider dramatic measures to reduce the cost of running the rail network.

The past decade has seen a renaissance in rail travel, helped by significant investment in services and infrastructure. Around 78 million passengers travel every year with ScotRail, which is responsible for 95% of passenger services in Scotland, up 25% since the franchise was awarded to its parent company First Group in 2004.

However, the growth in passengers has been outstripped by rising costs, with the bill for running the rail network passing £700 million this year. Among the suggestions made in a recent Government consultation, Rail 2014, to cut costs are getting rid of rules which limit the amount of time passengers have to stand to 10 minutes.

Passengers are facing a fare hike of 6% from next week, following seven years in which ticket prices have increased above inflation rates.

The figures show a similar level of overcrowding in the summer timetables of 2010 and 2011, despite the introduction of 38 Class 380 trains on routes from Glasgow to Inverclyde, Renfrewshire and Ayrshire from the end of 2010, which made 7500 more seats available on the ScotRail network.

Passenger Focus, the rail watchdog, said the figures illustrated a growing problem of limited capacity to meet increasing demand for rail services.

Robert Samson, the Passenger Focus manager for Scotland, said the next five years would be crucial in ensuring plans were put in place to provide more seats for passengers.

He said: "The introduction of the new 380s will have improved the ability of passengers to get a seat. It's improving capacity on a number of lines as the rolling stock it replaced is cascaded on to other routes.

"The onus is on the Scottish Government, Network Rail and ScotRail, who know where the capacity issues are, to plan for the increase in demand for services to make sure people are able to get a seat, which is one of the top four passenger priorities."

Mr Samson said a £1 billion investment in rail services in Scotland – the Edinburgh Glasgow Improvement Programme which will electrify the main Glasgow-Edinburgh line, increasing frequencies and cutting journey times – would help provide extra capacity but also increase demand for rail travel.

Network Rail is now consulting on the programme, but plans to purchase trains are yet to be made public. "Plans are in place for the next five to 20 years but what's needed is a commitment to fund those plans to free up capacity from extra services to meet demand," Mr Samson added.

A spokesman for the Scottish Government said: "Investment since 2007 has seen new services and trains introduced across the country.

"ScotRail currently plans the services in the timetable to minimise any forecast overcrowding. Passenger numbers information is used by ScotRail to inform the number of units for each service. The allocation of ScotRail's train fleet should reflect demand while trying to ensure passengers are provided with a seat within 10 minutes of boarding a train."

A ScotRail spokesman said: "We run more than 2300 services a day, with our fleet deployed in the most effective way possible to meet anticipated demand.

"Passenger numbers are monitored regularly, and we spend a great deal of time planning train movements.

"But there will be occasions when there is sudden demand for a particular service."

A spokesman for Network Rail, which operates track and signals, added: "We work constantly with our industry partners and government to identify ways of expanding capacity on the network."