Add to that the necessary additional Staff to cover Sick Leave and Vacation time and the cost is astronomical.
All scheduled Mail Routes must be completed, requiring the same number of Staff to be out on the road every day. The Logistics require inflated “stand by” Staffing, there is no way around it without disrupting required service levels.
Getting rid of Saturday Delivery would be a big first step, but it won't completely stop the hemorrhaging.
That's why just dropping them won't give you a 20% cut in carrier costs. However, there's a slightly different situation that has to be dealt with ~ the routes are designed to be covered ~ end to end (counting office time, street time, stop time, fingering time) ~ in 8 hours.
5 day delivery requires 40 hours of work anyway. Counting national holidays, sick leave, internal emergencies (storms that take carriers of the streets), retirements, accidents (cars hit carrier delivery vehicles), and soon, you end up having an average employee who works 4.5 days per week, not 5.0 ~ which means you need substitutes, and not just a PTF, or an OT regular carrier, but a level 6 to cover that extra 1/2 day. He will also need to be able to handle 10 different routes per week ~ which means he'll be among the more intelligent carriers and will likely move up to supervisory positions muchfaster.
A high level of employee turnover in your higher paid positions increases training costs substantually.
Although it's far more complex than i can explain it in these few words, what we have currently are 5.5 day routes covered by 4.5 day average workers, and cutting Saturday gives us 5.0 day routes still covered by 4.5 day average workers. The potential savings end up being this side of less than 1/4 of average out of pocket costs or an average carrier on an average day.
Plus, because the volume of mail to be delivered has an impact on carrier needs, backing up Saturday's mail into a 5 day week will require more routes!
There are solutions to the dilemma ~ (1) contract routes, then the personnel coverage problem is up to the contractor (sort of a modification existing rural delivery rules), (2) whack all door delivery ~ gives us a few extra hours in older white suburbs ~ bet that'd be popular, (3) whack all curbside delivery by installing kiosks ~ which does eliminate most street time and reduces accident ~ savings in Workman's Comp costs are MAJOR!
None off that is terribly revolutionary. In fact plans to do exactly that were worked up in the old Post Office Department in the 1960s. Congress objected so those things were not done.
Write your Congresscritters