Our municipality aim to widen a congested road inside the city in order to decrease congestion, while this road is not covered by public transportation yet .
I want to argue that if public transport cover this road no need to widen the road anymore .
Farooq, I did not get what do you mean by land reserve? Roads for cars and buses are the same. There is parking problem (and it matters a lot for land use in cities), but underground parking can be planned. Also, cars cannot be fully eliminated, at least in market economy. That is why basically land for roads is the same whether we have 100 buses and 100 cars, or just 1000 cars without buses.
At one conference I heard another article: how the share of public transport will influence the average time for a person to move across two points in a city. On one hand, car allows to connect all points, while for public transport we have discrete set of stops and some walk to those points is required. On the other hand, high fraction of private cars leads to traffic jam, and thus lowers speed. Finally, the optimal fraction exists, but it differs across cities.
One more aspect is economical: in a poor city few can afford cars, and public transport can be a success. in a rich city (especially in the USA) people value too much their leisure time and would prefer a car in most cases. Also, cities in US are not too dense, and traffic jam exists not in all.
Dear Yuri ! Thanks a lot
By " amount of land reserve " I have ment " the area of land allocated to passages "
This is the story ; our municipality aim to widen a congested road inside the city in order to decrease congestion , while this road is not coverd by public transportation yet .
I want to argue if public transport cover this roads no need to widen the road anymore .
Dear Farooq,
yes, you are right that the same road can be non-congested if the total number of cars per day is below let say 1000. Then non-congestion border can be written like C+aB
I thought a little bit about your complex question and read the other good answers. One problem that you face is that a road expansion could attract more cars, and a conversion of the road to some transit users is going to add to congestion .... so for example:
suppose we have a large residential area that produces trips and a large central employment zone (the central area of the city). Suppose they are initially connected by a road and this road is quite congested; what would happen if you added road capacity -- probably more flows? what would happen if you added a transit service to the road -- well some conversion of users to bus and some added congestion from the buses; what would be a real issue would be if the road added a BRT (bus rapid transit) --- so during the construction and conversion the road is terribly blocked by construction ... and after --- well some get a better ride on the bus but maybe the congestion for the remaining car passengers is worse! I think it is worth imagining some very scary scenarios -- I have seen (in Belo Horizonte Brazil) literally a bus traffic jam -- there is is congestion of buses!
I think what you probably need is a combined strategy and hopefully packing the demand onto a bus or public transit flow can help alleviate the traffic ... but I wouldn't be sure this will work -- this is a hard problem and there are too many moving parts that are interdependent
Dear Morton,
you are giving correct perspective in general but no policy advice. Well, one needs to think a lot before implementing such policies in the USA or highly populated cities in Brazil with car and bus congestion.
But Farooq is from Herat; see https://en.wikipedia.org/wiki/Herat . It is probably Afghanistan (although Iran also has a small city with similar name). I think that not everybody can afford a car there, and thus many would choose a bus (if available). I also think that road expansion will be more a problem for city budget than for leisure loss from congestion during its construction. (Just think about coefficient of income-leisure substitution in the USA, with high monetary value of 1 lost hour, and in Afghanistan with lower value of leisure). Also city is rather small (less than half-million of people) to have bus congestion. Taking those issues into account, I was making that constructive suggestion.
Hi Farooq,
You have many good suggestions above. I would also suggest that street packing photos dramatically show the difference in land used. These have been done around the world. Attached are from Honolulu. One shows a couple blocks of 4-lane street filled with rush-hour single-occupant cars. Another shows all the drivers without cars. Another shows all would fit into one lone bus. And finally, if they are walking or cycling they are hard to find. Add to that the land necessary for car storage during the day.
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