I apologize if this is slightly off topic, but it does seem to be in a similar vein.
I have run into the following situation multiple times to the point where I have developed a set tactic or approach to handling the problem. Also this approach has only been utilized in the lower levels (Chieftan through Regent). And on Large and Huge Maps.
Okay, I have this sprawling empire created by expansion and conquest (I deemed the land was unsuitable for the AIs use.

). More than half of all tiles are untouched beyond my core cities and the following things are occuring. I have Steam Power and am starting to link up this vast empire and Industrialization tech means I am starting to Gold-Rush Factories (or I have pre-built in anticipation of Industrialization) and now I am starting to get pollution. And I have been lazy by automating some of my workers once my core(s) were established. (Especially the abundance of slave laborers to auto-cut jungles. And especially if most of my attention has been drawn to fighting in major wars.)
Now if a polution appears on a tile without a road, you are done for, since all those (A)utomate and Shift-A workers are going to dogpile into that tile and lose a turn getting in, bring too many workers to get it done efficiently and take a turn to get out without even building a road for your trouble.
So, I have illustrated the problem, what is the solution? Well, I try to divide my workers into the following groups.
- Slave labor - automate for jungles and other automated tasks.
- My workers I split into three groups.
--- approx 60 % I rename (PTW only?) to 'RoadmaN'. These are the guys I send to link up the cities with railroads, to irrigate, etc. The two capital letters on either end is usually enough for me to spot them and differentiate them from some un-renamed worker.
--- approx 30% I rename to 'RADIOman'. These are the guys I send to clean up pollution as their primary task. But since pollution doesn't occur every turn, their secondary task is to build roads on all plains and graslands in the empire. This means they will be tasked for only a few turns before they can be sent off to clean up new pollution. I leave Hills, Mountains, Forests, etc to be roaded by the RoadmaN group. By having a force to road up the empire, I reduce the chances of the scenario I talked about above. And should the pollution appear on a tile without a road, my first workers are tasked with building the road and later workers with cleaning the polution, so the road is done before or on the same turn.
-- approx 10% are just floaters, doing misc tasks wherever needed. I don't rename these.