Under the proposals, first announced last September, lorries operating in the capital would be required to fit an additional window in the lower half of the cab door at a cost of around £1,000-£1,500 per lorry.
TfL said the only exceptions would be “a handful of lorries where retrofitting is not physically possible”.
London mayor Boris Johnson said: “The danger caused by HGVs to other road users is unacceptable and we have to reduce it. With the launch last year of my Safer Lorry Scheme, we have already made real progress.”
He added that nine cyclists died in London last year, the second-lowest number ever, but that seven of the fatalities involved a lorry.
“That is why we have to press on to the next stage. The cost per lorry is modest. The benefit to Londoners’ safety will be significant,” Johnson said.
However, the proposals for retrofitting windows previously came under fire from the freight industry as it was feared they would add significant cost.
Today’s consultation asks Londoners whether they support the principle of the scheme and the best way to enforce the new windows – whether through an extension to the Safer Lorry Scheme, or higher charges for non-compliant lorries under the Congestion Charge or Low Emission Zone regulations.
It also asks whether the restrictions should be full-time, part-time or route-specific.
TfL said implementation of any measures will involve close working with stakeholder groups, and the development of a legally enforceable “direct vision standard”.
Time would also be allowed for operators to make the necessary changes to their lorries.
The consultation paper also describes other potential modifications being explored for the future, such as lower cabs, larger windows and increased use of technology.
The consultation on side windows ends on 4 March.