No need to be embarrassed, it is confusing.   Revenue Ruling 99-7 has some good thoughts on it. 

Although #2 could possibly apply to some construction workers, I suspect most don't have a "regular" work location.

In general, daily transportation expenses incurred in going between a taxpayer’ residence and a work location are nondeductible commuting expenses. However, such expenses are deductible under the circumstances described in paragraph (1), (2), or (3) below.

(1) A taxpayer may deduct daily transportation expenses incurred in going between the taxpayer’s residence and a temporary work location outside the metropolitan area where the taxpayer lives and normally works. However, unless paragraph (2) or (3) below applies, daily transportation expenses incurred in going between the taxpayer’s residence and a temporary work location within that metropolitan area are nondeductible commuting expenses.

(2) If a taxpayer has one or more regular work locations away from the taxpayer’s residence, the taxpayer may deduct daily transportation expenses incurred in going between the taxpayer’s residence and a temporary work location in the same trade or business, regardless of the distance. (The Service will continue not to follow the Walker decision.)

(3) If a taxpayer’s residence is the taxpayer’s principal place of business within the meaning of § 280A(c)(1)(A), the taxpayer may deduct daily transportation  expenses incurred in going between the residence and another work location in the same trade or business, regardless of whether the other work location is regular or temporary and regardless of the distance.

https://www.irs.gov/pub/irs-drop/rr-99-7.pdf