A 10% increase in fares results in a reduced PT ridership of between 1% and 4%, according to estimates in available research, which focuses on the impact of PT fare increases.

Bus fare elasticity averages around −0.4 in the short run, −0.56 in the medium run and −1.0 in the long run; metro fare elasticities average around −0.3 in the short run and −0.6 in the long run, and local suburban rail around −0.6 in the short run.

There are variations by region and by type of city.

In Aubagne (France) there was a 135.8% increase in ridership, from 1.9 million passengers transported in 2008 to 4.48 million in 2011 with the introduction of fare-free PT and network modernisation. Among the new passengers, 50% previously used cars, while 20% cycled and 10% walked. 63% of new PT trips generated by fare abolition would otherwise have been performed by a motorised vehicle, according to studies conducted by the local authorities. Evidence also shows even greater increases in small- to middle-sized areas, although those increases may start from very low bases.

The potential CO2 benefit of such fare reductions will depend on the type of public transport means for which the fare is decreased, its specific CO2 emissions, and the type of mode shift that is achieved.

Parking pricing can encourage a mode shift from the personal car to more sustainable modes of transport including  public transport and active  modes. Parking policies can also encourage the use of more environmentally-friendly personal cars, if appropriately priced.

A parking pricing policy that maintains approximately 15% of on-street parking spaces available, cruising for parking - estimated to account for up to a third of urban road traffic - can be almost eliminated. The CO2 savings will be proportionate for ICE vehicles.

Such policies are more readily acceptable to the public if revenues generated are used to improve the public space.

In general, a 10% increase in parking prices results in a 1-3% decrease in the demand for parking.  

Congestion pricing can reduce transport CO2 emissions by triggering a shift towards the use of less-emitting transport modes, such as public transport or more fuel-efficient vehicles, where these are charged less for road use).

London’s road pricing scheme reduced road traffic’s CO2 emissions by 16% within the congestion-charging zone in and by around 1% for all of London.

In Italy, Milan’s road pricing scheme reduced traffic by 12% within the specified zone and by 3.6% outside it. Traffic shifted to public transport (48%), to surrounding areas (35%) and to cars exempt from the scheme (17%).

CO2 reductions from road pricing schemes can be maximised by enlarging the zones and by optimal pricing for Internal Combustion Engine (ICE) vehicles.