Last week Brian Paddick and I launched a fairer fares package ahead of this year’s London Mayoral and Assembly elections.

Boris Johnson has been Mayor of London since 2008. In just four years he has increased the cheapest bus fare from 90p to £1.35 – and he had planned to raise fares even further until the Coalition Government stepped in and helped limit the rise. As well as bus fares, the cost of travelling on the Tube, the Docklands Light Railway, the Croydon Tramlink and the London Overground have all soared under Mr Johnson’s mayoralty.

Of course there is the argument that investment in public transport has to be paid for by someone, and surely passengers have to pay their fair share? There is of course an element of truth in that. Yet accepting that there is still a need for investment to continue in the tube network, does that let Mayor Johnson off the hook? Of course not. There are realistic alternatives to his fare policies.

One thing’s for certain – that realistic alternative is not being put forward by former Mayor Livingstone. His fares package which would cut fares by 7% for 18 months may seem attractive at a first glance. The simple truth is that the numbers do not add up – it is not affordable. The reality is that Mr Livingstone won’t be able to deliver this and many suspect he is just repeating his old tricks of the past.

Just look at his record. In 2000 Ken Livingstone stated in his manifesto: “I will freeze bus and tube fares in real terms for four years.”

What actually happened was bus and tube fare increased well above the rate of inflation in his four years as Mayor. The same thing happened in his second term, indeed take a look at these fare rises Ken Livingstone proposed for the year 2007. In this year alone the overall increase in bus fares was RPI plus 3.8 per cent. The rise in tube fares was RPI plus 1 per cent. Only when it came to his re-election year did fares miraculously suddenly reduce for bus passengers from £1 to 90p. Funny that!

It is clear from his track record that the former Mayor can not be trusted on affordable fares, and the current Mayor has hiked them up year on year. So where does that leave the Liberal Democrats?

Our position is quite simple. We won’t make unrealistic pledges. We think investment must be maintained in London’s transport network and we won’t put it at risk. Too much of the tube network is still creaking from decades of under investment.

Our plans are simple and about fairer fares. People should be able to get to work at a reasonable cost. When people on the lowest incomes find it difficult to afford their travel to work, then there is something seriously wrong with how a city is working. London Liberal Democrats are therefore advocating three simple policies.

A one hour bus ticket

It really is ridiculous that you can’t change from bus to bus in a short period of time without being charged several times. Passengers can change from one tube line to another without being charged again. Time limited bus tickets exist in cities across Europe. It really is time we caught up and helped people who rely on buses.

Early bird fares

London’s economy is reliant on an underpaid army of workers, from cleaners to security staff, who get to work before most people have even got out of bed. Discounted fares for people who complete their tube journeys early in the morning would greatly help London’s low paid. And, this would also help reduce rush hour congestion.

Part time travel cards

Some of the lowest paid work is carried out by part-time workers, the majority of whom are women. Yet most fares are structured around people who work a conventional five day week. We need to introduce a part time travelcard that provides far cheaper travel than is currently available, for people that only travel to work up to three days a week.

These three proposals, combined with tackling the outrage of Oyster overcharging, add to an effective package that we should be proud to campaign on over the coming weeks. They won’t cost the earth, but they will make a fundamental difference to people with the smallest pockets.

Fully costed

Most importantly, our fairer fares package is affordable. Through targeting waste, fare evasion and certain perks provided by TfL we are able to fund our plans, without impacting on the transport investment programme.

Our very specific and targeted measures that particularly help people on low incomes clearly exemplify how the Liberal Democrats are the only party in the May elections with fresh and innovative ideas for London.

* Caroline Pidgeon is a Liberal Democrat London Assembly Member and Deputy Chair of the London Assembly Transport Committee