just as in the case of concessioned buses no fare adjustments are conducted regularly and when increases happen these are quite significant and are not expected by the population this has increased political pressure to keep tariffs low as social protest arises each time a substantial increment is implemented a december survey of underground users showed that of respondents agreed with a fare increase from mxn to mxn if the government could guarantee a decrease in crowding waiting times delays in service as well as improvement of trip conditions such as air conditioning and improved safety mitofsky this fare increase was implemented in however public faith in its ability to realise the promised improvement has been dented by major events such as the need to stop operations of the newly constructed line due to the acquisition of unsuitable trains and the collision of two trains in may el economista in the case of the underground the gap between real and actual fares meant a loss of almost mxn million in revenues in