If you are in London reading this, then you should stop and marvel at the engineering genius of the Crossrail tunnels running some 40 metres deep beneath you. Each of the two new tunnels (one going eastbound and the other westbound) is 21 kilometres long and 6.2 metres wide.

In some places, such as Tottenham Court Road, the tunnels pass within a metre of existing Tube platforms, and elsewhere Crossrail has had to weave them to run precariously around historic buildings.

Luckily for the brilliant engineers who have designed this extraordinary subterranean world, London clay is suitable for tunnelling — which is the reason the Victorians built one of the earliest underground systems in the world.

On every level, the £14.8 billion Crossrail project is one of the most delicate and complex balancing acts of civil engineering ever to have been built in Europe. When complete in December, the new Elizabeth line will stretch 120 kilometres from Berkshire to Essex through 41 stations, and carry more than 200 million passengers a year.

Until now, apart from teething problems, Crossrail has run smoothly. So reports that it may need a bail-out of £500 million to finish the final touches on time is a disappointment. Last-minute problems with power supply and signals are apparently to blame.

Read more Property firm Helical catches a £120m deal at Crossrail site

Is this a surprise? Running over-budget is not unusual for such a mammoth project, and Crossrail hopes to make up any shortfall by spreading the cost over time from fares and rates.

Mischief-makers who say this hiccup shows again how awful Britain is at delivering mega-projects on time need to pipe down. For every disaster, such as the West Coast rail electrification or the Heathrow delay, there are great successes, such as the St Pancras Eurostar service and the Olympics.

Think about this: it’s taken Crossrail only five years to organise tens of thousands of people, working in tunnel gangs of 20 at a time, in 12-hour shifts, 24 hours a day and seven days a week.

These workers have operated eight giant tunnel-boring machines, weighing the same as 143 buses, to excavate eight million tonnes of earth in order to build the tunnels on time and without accidents.

It’s a myth that the British are worse than our peers at big projects, and when it comes to engineering, we may well be better than most. Spare a thought for Rome. The eternal city has been waiting for its new Metro C line to open since 1990. San Giovanni, the main station, finally opened last weekend, running hundreds of million euros over budget, over deadline and with a few corruption scandals along the way.

In Amsterdam, the city’s second metro line is due to open in July — 10 years after it should have been finished. It was also over-budget.

Nor are the French, lauded for their “grands projets”, immune from problems. EDF Energy has warned that its nuclear power station at Flamanville is behind schedule and over budget. So too is the Finnish reactor it is building. What effect EDF’s problems will have on Hinkley Point C is still not known.

Denmark’s biggest construction project, to build the longest immersed tube tunnel in the world, between Denmark and Germany, is being held up because of legal problems. The tunnel has been in the planning for 10 years, but the ferry companies are taking the EU to the European Court of Justice over state aid. One to watch.

All big infrastructure projects run up against the buffers, particularly when government and their agencies, such as TfL, are involved, as they are with Crossrail. If one were to play the sceptic, this is because governments allow projects knowing they are being optimistic with their figures. But it is also easy for them to assume by the time the projects are finished, the public will have forgotten either delays or budgets.

Where the Government can be justly criticised is for delaying endlessly over decisions on whether to give the go-ahead to big projects such as Heathrow’s third runway or new nuclear stations — whether yes or no.

Central government is too timid about giving local councils permission to raise private capital from outside investors.

Cambridge, for example, is lobbying the Government for more devolved powers to keep more of its tax revenues and raise outside money for precisely this sort of project — the city fathers are considering an underground network to solve traffic woes. They should be set free to do so.