Campaigners are calling for a new deal for India's women in the wake of the death sentences handed down by a Delhi judge to four men who tricked a woman and her male friend on to an out-of-service bus before gang-raping her so brutally that she died later from her injuries.

The case brought women's rights protesters across India on to the streets in angry demonstrations against the country's culture of violence against women, from female foeticide to rape. But activists fear the intense focus on the court case will do nothing to improve the safety of women on city streets. A new report by three Indian academics supports those concerns and says it is India's infrastructure that needs to change, from bus services to public toilets.

Pending an appeal expected to be lodged this week, four of the six guilty men – one died in jail and another was sent to a young offenders' prison – will be hanged under changes made to Indian law as a direct response to the case, making aggravated rape punishable by death and fast-tracking sexual offence cases through the courts.

Issuing his decision, Judge Yogesh Khanna said the attack "shocked the collective conscience" of India. "In these times, when crime against women is on the rise, the courts cannot turn a blind eye toward such gruesome crimes."

There were nearly 25,000 reported cases of rape in 2012 in India. In Delhi, with a population of 15 million, more than 1,000 cases were reported in the year to mid-August 2013, against 433 reported in the same period last year. In Jharkhand state, to the south-east, more than 800 cases have been reported in the past seven months, including a gang rape of a schoolgirl. There were 460 reported cases in all of 2012. The rise may be in part due to increased reporting, but India's National Crime Records Bureau says registered rape cases in India have increased by almost 900% over 40 years, to 24,206 incidents in 2011. Some activists say one in 10 rapes is reported; others one in 100. In a 2011 poll nearly one in four Indian men admitted to having committed some act of sexual violence.

But the report Invisible Women, by academics Shilpa Phadke, Shilpa Ranade and Sameera Khan – due to appear in the next issue of Index on Censorship magazine – reflects a real fear that at the end of the Delhi trial the media spotlight will move on from mistreatment of women.

The report argues that India's infrastructure needs to be transformed to give women an equal and safer place in cities. They write that the Delhi rape "was facilitated in part by the lack of adequate public transport, which meant that she was travelling in a private bus". The women point out that transport, lighting, toilets and other public facilities are designed with an "invariably male" user in mind. As a result, women's toilets "are dark and unfriendly" and often close at 9pm, "sending the clear message that women are not expected to – and not supposed to – be out in public at night". This means women "have to learn extreme bladder control and to negotiate dark streets and unfriendly parks".

The link between access to toilets and rape is an issue in rural areas as well. In May it was reported that most rapes in the state of Bihar occurred when women went outside to the toilet at night. The authors claimed shopping malls were the only places in India's cities where women felt safe. Streets need to be well-lit, public transport needs to be regulated and to run day and night, and safe toilets need to be available.

"We need to move beyond the struggle against violence and articulate women's right to the city in terms of the quest for pleasure," the report says. The victim in the bus rape had been to the cinema. "Changing attitudes may take time but the provision of infrastructure can be a simple one-time policy decision, which reinforces the point that women belong in public space."

In Mumbai, a scheme for women-only train carriages was seen as a great success because it "enshrined their right to be there", the authors write.

The report illustrates the determination of activists to keep the issue from fading. "It is the beginning of our movement," said Anuradha Kapoor of civil rights group Maitree, who was arrested in June at a women's rights protest. "We won't give up so easily."

Writer Nilanjana Roy agreed: "The rapes might not stop, but this conversation isn't stopping either."