TENS of thousands of rail users face chaos as work starts on a £742million track upgrade.

Around 35,000 commuters will face transfers, changes to routes or travel by bus.

Rail bosses admit there will be significant service alterations for passengers who use the central belt rail network which will "undoubtedly" cause inconvenience.

The electrification of the line between Glasgow and Edinburgh will see the closure of the Winchburgh Tunnel for six weeks.

And will mean no direct trains from Queen Street high level to the capital from Saturday June 13 until Sunday July 26.

Instead, passengers can take trains from Queen Street low level via Bathgate and Airdrie or from Glasgow Central either via Shotts or Motherwell/Carstairs.

Commuters will be forced to take part of their journey on buses.

Each week, 311 trains travel between Queen Street high level station and Edinburgh via Falkirk High with an average of 130,000 passenger journeys each week on the line.

Just less than a quarter of trips are between Glasgow and Linlithgow so are unaffected by the tunnel closure, almost half are between Glasgow and Edinburgh and can transfer to alternative direct services meaning 28% of journeys will involve travelling part of the route by bus.

Tomorrow, preparatory work begins in advance of the rail tunnel work which will allow the track to be lowered.

The work should result in cleaner, greener and quieter trains.

Network Rail's website warns: "If you travel end to end between Glasgow Queen Street high level and Edinburgh, we recommend you use the alternative direct services. This will be a quicker journey on one train all the way.

"Services on other routes between Glasgow and Edinburgh are expected to be much busier than usual with additional customers travelling end to end.

"If you normally board at a station en route, you may not be able to get on the first train you aim to catch.

"As a rule of thumb, you should try to set off 25-30 minutes earlier than normal if you want to arrive at your normal time.

Network Rail says it does not plan to hire extra trains but will be using every train at its disposal.

The website says: "If you follow our travel advice we will still be able to transport the vast majority of you by train or a mix of train and bus.

"We have also altered our train maintenance regimes to allow us to have as many trains as possible in passenger service at any one time. This worked very well for the Commonwealth Games.

"We will be using every carriage we have at our disposal, however at peak times you may still have to queue to board trains and may not get on the first train you aim for."

Smartcards and paper season tickets can be used on the three alternative routes to Edinburgh from Glasgow Central.

Passengers will not be reimbursed for the extra journey times but will be entitled to compensation if they are delayed by more than 30 minutes.

A city council spokesman described the work on the Winchburgh Tunnel as an essential to improve train services between Glasgow and Edinburgh.

He added: "We know Network Rail and ScotRail are working closely on minimising the disruption and they have both kept us informed of their plans.

"We are confident they will put appropriate measures in place to make sure passengers can still travel to and from Glasgow and that the impact on the city is as low as possible."

Glasgow Chamber of Commerce chief executive Stuart Patrick said: "We are cautiously welcoming both the Edinburgh to Glasgow rail programme and motorway improvements being carried out between the two cities throughout this and next year and appreciate that when completed these works will make it easier for our members to get to their main markets and for visitors and investors to get to Glasgow.

"However there is a real issue over the disruption that will be caused due to rail and road works taking place at the same time and a danger both our rail and road systems will be operating below par simultaneously.

"It certainly came as a surprise to us that all these works were in the pipeline.

"We hope that the Winchburgh Tunnel experience will tell us all we need to know to minimise the effect of the much more challenging 20-week closure of the Queen Street tunnel in 2016 and will be watching closely.

"This summer is when we want to start seeing all those new visitors arriving in the city following the raised profile from the Commonwealth Games success.

"City centre businesses are looking for a steady increase in summer trade, not an unwelcome and unexpected dip that could come from reduced and difficult access to Glasgow. We don't want the next two summers to be remembered for all the wrong reasons."

A NUMBER of other rail engineering projects will be under way over the same period work is being carried out on the Glasgow to Edinburgh rail line.

Over the weekends of May 30-31 and June 6-7 trains will run between Glasgow Queen Street high level and Polmont and buses will replace trains between Polmont and Edinburgh.

On the weekend of July 11-12, buses will replace trains travelling between Glasgow Central and Carfin on the Glasgow Central/Shotts/Edinburgh line.

That same weekend passengers travelling from Edinburgh to Glasgow Central via Motherwell will have to change trains at Motherwell for alternative services to Glasgow Central.

On Saturday June 13 and every Sunday between June 14 and July 26 replacement buses will run between Falkirk Grahamston and Edinburgh on the Glasgow Queen Street high level route.

On Saturday May 30, Sunday May 31 and Saturday June 6, trains between Glasgow Central and Lanark will terminate at Motherwell with onward travel to and from Lanark by bus.