The fact that making such an estimate would be difficult and prone to error is not a rationale for dismissing it. Reduced Congestion Measuring congestion costs is just as difficult as measuring mobility benefits. While it may be relatively easy to put a value on the fuel consumed, fuel is a small component of the cost. Time is the largest component of the cost. Estimating the value of time lost in traffic congestion is subject to large ranges of error.
Different drivers place different values on their time spent in traffic.
This means that more than half the drivers are choosing to join the traffic jam. Apparently, these individuals place a very low value on time lost in this way. Another illustration of the problems associated with valuing this lost time is the fact that only a minority of vehicles in the California SR 91 corridor choose to save time by paying to use the HOV lane. The majority choose to spend the time rather than the money. Aside from the difficulty in valuing the time consumed in traffic jams, there is the problem of ascertaining the impact that an increment of public transportation has on this congestion.