They are “doing more damage to London,” said the former chancellor Lord Lawson in the House of Lords, “than almost anything since the Blitz.” In the same spirit of absurdist hyperbole, they might be said to be the most transformative public works since Joseph Bazalgette built London’s sewers and river embankments. They are not, but they do have the potential to change the spirit and character of the capital and of other cities that follow the same path, as well as making its transport cleaner, healthier, safer, more efficient and better able to deal with growing pressure of numbers. They might even prove that the city’s former mayor Boris Johnson was capable of doing something right.

“They” are the cycle superhighways, the most conspicuous of several measures promoted under Johnson. They add up to an unprecedented plan, which is to make the sprawling, awkward, inconsistent city of London bike-friendly. The places most often cited for the exemplariness of their cycling provision – Amsterdam, Copenhagen, more recently Manhattan – were already more ordered, compact and coherent in their layout. In London, the street pattern changes moment by moment, straight to winding, leafy to truck-thronged, wide to narrow.

This in turn reflects the politics of the city, in which power is diffused among its 32 boroughs, plus the City of London, each with its own identity and attitudes. The city’s mayors, for all their ability to attract headlines, have limited means to enforce their will. The superhighway network therefore has to deal with the fact that the royal borough of Kensington and Chelsea doesn’t want them on its land, meaning there will be a highway-free void in the middle of the capital. In the City, meanwhile, the impatient, assertive people who work for the financial industry won’t wait long for the red man to turn green, which means they don’t take well to the elaborate multi-phase traffic lights, at which bikes, cars and pedestrians must patiently wait their turn.

Former London mayor Boris Johnson meets one obvious dissenter as he cycles across Vauxhall Bridge. Photograph: John Stillwell/PA

Andrew Gilligan, the journalist who became Johnson’s cycling commissioner in 2013, says that “a lot of councils are really cowardly” and that while majorities usually support cycling schemes, local politicians are easily impressed by vocal minorities. In Kensington and Chelsea, he says, it only needed 15 objections from residents for one proposal to be stopped. It therefore required Johnson’s “leadership” and investment of “significant political capital” to make anything happen. Gilligan himself is not an especially diplomatic figure. “He pissed off large numbers of people,” says one involved in London’s bike politics, “but he made it happen.”

Cycling infrastructure, as commonsensical and humdrum as it might seem, is not just about engineering. It is political, cultural and social. It has to reconcile territorial disputes between people on bikes, people in vehicles and people on foot and between different kinds of cyclist. It can take on aspects of class conflict, in which drivers sometimes cast themselves, counterintuitively, as underdog victims of a two-wheeled elite. It obliges choices as to what kind of city its citizens and politicians want, with what balance of public benefits and private freedoms and for whom.

Just before he left the mayoralty this spring, Johnson inaugurated a stretch running along Bazalgette’s Victoria Embankment from the City of London to parliament. Cyclists applauded him as he rode along it. Van drivers hurled obscenities. Running through the centre of the city and the districts of the country’s government, past landmarks such as the Tower of London and the Palace of Westminster, it was the most conspicuous of his interventions, symbolic confirmation that new cycle routes were not marginal but as important to the running of the city as railway lines and roads for vehicles.

Municipal sphinxes have left riddling signs that have to be interpreted at speed

The route, called the east-west cycle superhighway, is contentious. Taxi drivers hate it. It affects the car-bound journeys of people of power and influence: Lord Sugar moaned during its construction and Sir George Iacobescu, the man in charge of the Canary Wharf development, said it strangled traffic, and lobbied Downing Street against it. The Royal Parks objected to a proposed extension past Buckingham Palace. Gilligan says that Boris “kept being harassed by MPs, colleagues plucking at his sleeve and complaining that their drive from wherever had got longer by so many minutes”.

For the cyclist, the east-west superhighway is the most impressive part of a system that can be ramshackle in parts. It is broad and stately, under the embankment’s plane trees, well separated from fuming drivers alongside. It feels safe. When complete, it will run alongside St James’s Park, through Hyde Park and onwards, making it possible to ride 18 miles from Barking in east London to Acton in the west, and be separated from traffic almost the whole time. It was announced last week that it will be joined by a route north from Oxford Circus, through Regent’s Park to Swiss Cottage, after the new mayor, Sadiq Khan, approved it.

A superhighway, in theory, is a route that separates cyclists from other road users, although early examples achieved this sketchily, with strips of blue paint that acted more as ignorable suggestions than actual barriers to trucks and cars. It is linked to other measures given catchy names by the journalists Johnson and Gilligan. There are “mini-Hollands”, whereby three outer boroughs get to share £100m on making local improvements. There are also Quietways, which join up the slack and underused byways of the city to make safe and unthreatening routes. The first of these runs six miles from Waterloo station to Greenwich through council estate car parks, little-known parks and along disused railway embankments. Created with the help of the charity Sustrans, it opened in June.

The logic, says Gilligan, is that London is facing ever more demand for transport and that encouraging bicycle use is the best way to meet this demand. Building more roads on the congested and high-priced land is physically and politically unfeasible. Expanding the underground network is slow and expensive. A cycling commuter takes up much less space than one in a car, which rather obviously means that they use the existing roads more efficiently. Cycling has the added benefit of reducing pollution and benefiting the health of participants, at least of those who don’t get injured.

‘Contentious’: a section of the east-west cycle superhighway. Photograph: Transport for London

What stops more people riding bikes is danger and the perception of danger, especially among parents with children, women and older people. The risk of death is actually small and declining: figures from Cycling UK show 33 deaths out of 90m London cycle journeys in 1989, falling to nine out of 270m journeys in 2016. But well-reported tragedies such as the death of 26-year-old Ying Tao outside the Bank of England last year, induce understandable fear. The idea of superhighways and allied measures is both to be safer and to feel safer, so that more cautious cyclists will venture out. Few school runs are made by bike and campaigners want to change this.

In its current state, the incomplete system imperfectly achieves these aims. The Embankment stretch is mostly glorious – “Just before it opened I had trucks snarling down my back,” says one user. “Afterwards, I could chat to a colleague as we went along” – but it unravels into confusion at its end. Elsewhere, the network can be inconsistent and bewildering. Municipal sphinxes have left riddling signs that have to be interpreted at speed: turn-right-give-way-cross-turn-left, turn right in two phases only, go left in order to go right. Inscrutable numbers and symbols refer to a higher concept that is imperfectly explained.

There is a plethora of special conditions, works of intellectual ingenuity that as soon as comprehended change into something else. You have to decipher which half-defaced cycle logo on the pavement and which little blue sign is telling you where to go and how to behave in relation to pedestrians. They, also confused, may swear at you in the belief that you are encroaching on their space. At some point on an unfamiliar route you are likely to lose the thread and find yourself discharged into the hostile realm of HGVs. It resembles an old-fashioned board game: go back three spaces, throw a double to avoid the Dark Forest or a six to find the Magic Bridge.

The Lycra lout, with his unpleasant musk of sanctimony and testosterone, looms over all discussions about cycling

Objections are not all from privileged lords. A mini-Holland in Waltham Forest, north-east London, brought out a multi-ethnic, not-posh crowd of hundreds of protesters objecting to its effects on shops and traffic congestion. A Conservative councillor, supporting the objectors, said that cyclists are “almost entirely middle-class, young white men”. Gilligan dismisses this argument – “It’s complete rubbish to say the motorcar is the bastion of the poor” – but the row shows that the virtues of cycling are not always self-evident to everyone.

Gilligan, like other pro-cycling campaigners, has a series of arguments to refute the most common objections. Cycling routes are usually good for shops that lay along them, they say. Traffic will adapt to new circumstances. “People think it is like water and if you narrow the pipe it will flood,” says Gilligan, “but it is not a force of nature. It is a product of human choices.”

If you give less road space to cars and improve conditions for cycling, in other words, more people will give up driving. There will still be congestion, but for other reasons than new cycle lanes – “population growth, the rise of Uber cars, cheaper petrol”.

His basic argument is indeed overwhelming: it can only be good if more people use a city’s roads more efficiently, at less cost to themselves and in public expenditure, while causing less pollution and less danger to themselves and others than is created by driving. More than that, a city that is more pleasant for cycling should, at least in theory, be more pleasant for everyone else. Sustrans says its new Quietway has helped civilise an area around Millwall Football Club, whose character was previously dominated by brutal fences for segregating fans. At their best, mini-Hollands create quieter, calmer zones for pedestrians. The Victoria Embankment is now a better place for walking thanks to the buffer that the cycle lane creates between pedestrians and cars.

‘It resembles a board game’: a superhighway junction at Cambridge Heath, east London. Photograph: Matthew Chattle/Rex/Shutterstock

Yet we fall short of Utopia, not least because too many cyclists are themselves imperfect citizens. The Lycra lout, with his unpleasant musk of sanctimony and testosterone, looms over all discussions about cycling. Peter Murray, chairman of New London Architecture and a passionate cyclist, recalls the “die-in” held to commemorate Moira Gemmill, the design director killed in Westminster in April 2015. The roundabout where she died was briefly closed as cyclists lay on the ground in protest. Taxis, vans and scooters respected the moment. “The only people who spoiled it were the Lycra brigade”, who insisted on picking their way across.

Val Shawcross, deputy mayor for transport under Sadiq Khan, wants to promote walking as much as cycling and says the latter should be “for all ages and genders”. So it is essential that superhighways achieve their ambition of attracting different, gentler users. In the short term, they are more likely to increase aggression: drivers, for example, now shout at cyclists if they don’t use the highways. There has been a kerfuffle about lunchtime joggers using the cycling surface, although Murray and other regular cyclists are relaxed about this. The name “superhighway” is unhelpful, as it suggests an unimpeded charge, Froome-like, along the Champs Élysées, and their shade of blue implies a cycling equivalent of motorways. In reality, as cyclists are slowed down by crossings for pedestrians and detours behind bus stops, they require a more careful pace.

There is a strong suspicion that Boris Johnson rushed through his cycling plans in order to claim credit before his mayoralty expired, with the combination of self-aggrandisement and inattention to detail that typified his other grand projects. There are indeed glitches. Shawcross accuses him of causing unnecessary disruption by starting too many roadworks at once. But, given the blind unreason of Lord Lawson, and the capacity for obstruction offered by the complexities of improving cycling in London, this is an occasion to be grateful for his gung-ho spirit.