Yes, according to the park website, "Trails are open daily from dawn to dusk." https://www.dauphincounty.org/government/departments/parks_and_recreation/dauphin_county_parks/detweiler.php
To my knowledge the trails & park are open dawn to dusk. The building staff (co-op extension, Dauphin County Soil Conservation District) are present 8-6 M-F.
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