Seattle, WA -

A study of the economic impacts of sending up to 18 more coal trains through Seattle says there would be benefits as well as costs.

The study was announced in December by Seattle Mayor Mike McGinn, a coal train opponent, who released results Friday on his blog.

The Seattle Times reports the mayor held onto the results for five weeks and released it after the paper filed a public disclosure requests.

Supporters of the proposed Gateway Pacific export terminal at Cherry Point in Whatcom County say the study shows it would have a net positive impact on Seattle.

The $25,000 study was conducted by Community Attributes. It found the terminal would trigger construction and add jobs. It also found the trains would increase congestion and reduce some property values.