In several countries, the governments taxed vehicles in the centre of the city during peak hours in order to reduce traffic congestion. I believe this is negative for two reasons.
Firstly, a lot of people would not be ready and willing to pay such taxes just because they are using their own car or a truck to get somewhere during rush hour. Admittedly, for some people it is not a problem to pay extra, but there are also those, who are headed to work every morning, prepared to work hard just to feed their family. There are families that can not afford it, unless they cut the budget, which sometimes can be critical. It is not really fair to make everyone pay such taxes, this action could lead to disorder in the city, because upset families may be more likely to protest in this situation.
In addition, I do not think that making people pay taxes for their vehicle will actually solve the problem of traffic jams. Probably, the number of people on roads during rush hour will decrease, but not significantly, because the rush hour is usually in the morning, when people rush to work that they can not be late to, so there is no way a lot of people will either refuse to go to work or reschedule their worktime just because of the taxes.
In conclusion, on my opinion, introducing a tax on a vehicle during rush hour is a negative development, because it can lead to disorder in the city and may not solve the problem of traffic congestion.