When we have situations like this here at RPM, we can appeal the appraisal. I would be curious to see the actual report and how the appraiser adjusted the comps for this attribute. I agree that sometimes the appraisers are not familiar with an area and this can contribute to an excessive hit to your value. If you'd like me to have a look at the report itself, let me know and I'd be happy to advise --- free of any charge or obligation.
Traffic will only grow greater w/time, and many people cannot adjust to constant noisy road traffic.