That research is useless! Sure they measured it, so it isn't wrong. However it is useless. What it is really saying is your city was so bad that people were not taking advantage of living in the city because they couldn't conveniently get places. Those people could have lived in rural Montana for all the good a city did. Cities are about all the things you can do by living in it, so if people change because of new roads then you are a city were not meeting their ideals.
Also note that they measured one lane. I already asserted that by the time a city is thinking about adding one more lane they already need to add 6 times as many lanes (not 6 more lanes, 6 times!) IF your city needs 6 times more lanes than it has, no wonder people are choosing alternates, and once a lane exists they will start using it.