Mainebrown, here's some relevant language from the New England Supplement, although I'm not sure how it applies to you if you are mostly on layoff and only working occasionally. Probably depends on what additional details your Business Agent has worked out with Management.
ARTICLE 57 --- SENIORITY
Section 2 --- Bidding
(A) Biennial Bid
(1) In each location, a schedule of all starting times in each classification shall be posted for bid on the second Monday in February and shall remain posted for two (2) weeks.
Package (Metro) driver starting times shall also include the general area of the route and feeder driver starting times shall also indicate if the assignment is over or under 140 miles.
(2) Full-time seniority employees, in the order of their seniority and provided they are qualified for the job selected, shall have the right to select starting times in any classification (except Lead Drivers) from the schedule posted. Except as provided herein, such selection shall be held until the next bid.
ARTICLE 66 --- HOURS OF WORK AND OVERTIME
Section 1
(a) Five (5) days shall constitute a normal week's work for local employees from Monday to Friday, inclusive, and the hours of labor each day shall be worked in uninterrupted succession. All time worked in excess of eight (8) hours per day shall be paid for as overtime at one and one-half (1½) times the normal rate.
(b) Full-time employees hired after July 31, 1987 shall have a workweek of five (5) consecutive days, Monday-Friday or Tuesday-Saturday.
(c) The schedule when changed shall be posted by the Employer on Monday to become effective on the following Monday.
Section 2
(a) Employees ordered to report for work before their starting time shall be guaranteed eight (8) hours' work or pay in addition to the time worked before their starting time, with time and one-half (1½) for all hours worked over eight (8) hours. Any employee ordered to work after his regular starting time shall have his time refer back to his regular starting time.
(b) Employees ordered to report for work before such starting time shall be paid at time and one-half the appropriate rate for that day for work prior to the regular starting time.
(c) Part-time employees called to work before their regular start time shall be paid at straight time for work prior to the regular start time plus their guarantee.
Section 3
(a) Any employee who is called or reports as scheduled, unless advised not to report, shall be guaranteed a minimum of eight (8) hours' work or pay.