A study from Denmark suggests that it may have some impact.
The researcher looked at 65,000 Danish women who delivered between 1996 and 2002, and interviewed them to determine, among other things, how long it took them to conceive. They also looked at the traffic volumes for their neighborhood to see if they could compare the two.
They found that for every 10 decibels of additional traffic noise, there was a 5-8% increase in the chance it would take more than six months to conceive.
Fortunately, increased traffic noise did not affect a couples chances to take longer than a year to get pregnant. Infertility is defined as a disease in which a couple is unable to conceive after one year's time, so the traffic noise itself did not cause infertility.
They could not determine whether the delayed time-to-conception (TTC) was due to the male or female partner, and the this delayed TTC was not affected by other factors such as poverty or levels air pollution that could delay conception.