If you have more than one regular place of business and at least one is away from residence, all costs going between residence and temporary work locations in the same trade or business are deductible regardless of distance. Rev. Rul. 99-7.
If residence is principal place of business within meaning of §280A(c)(1)(A), can deduct costs of travel between residence and any work location in same trade or business, regardless of distance or permanence of worksite. Rev. Rul. 99-7
“Temporary”: Realistically expected to last less than a year absent facts and circumstances to indicate otherwise. If it changes later, temporary until point that expectations changed.