This is a location that define a setting, a campaign. It is not something to casually drop into your world unless you want to center your campaign around it (players will take to The Road like ducks to water). It works best with modern characters travelling to places new, but you can use any group of people.
Time is a roadway, with exits and side-roads leading not only to the past, present, and future, but to many variations thereon.
The Road appears to be a well maintained road of the best kind. For some campaigns it will be a Roman Imperial Road, others just a well packed dirt road, yet others still a super highway (and in some campaigns it will change with the times). North on the road leads to the future (usually); to the South, the past. Along The Road there are varous signs that mark side roads. Those signs list various times and places. If one follows that side road (ramp), the side road will lead to that time and place. (The Ramps seem to exit out on a main road/ path for the area). Most of the exits in a given area lead to the same time, just different places, but not always. Some odd ones lead to the past or odd worlds. Some of the branching roads lead to side roads, where alternate histories exist (or what some people think of as alternate history).
The terrain along The Road is archetypal. It is just the open terrain and a lone road running through it. It is not all abandoned. Along the road, far and between, there are various inns and services, of people who travelled the road and for some reasons decided never to go on. (Most of them just got lost and could not find their home again).
Only a small number can find The Road innately (They have a pathfinding knack). Others can be led to it, but will have difficulty refinding the exit/ entrace. (If someone travels the road for a while, they might pick up the pathfinding knack).
A small side note: If you change the past and reach The Road, you will find the newly appeared sign that leads to the alternate timeline you created. You can travel up that road if you want. If you can change the event enough times (finding most of the exits) you can make your changed history part of the main road.
A tip of the hat to Roger Zelazny who created all the good ideas in the multiverse.
The most common plot is that some Gandolfian Cosmic Mage type finds the PCs and recruits them for a mission into the past (or future). The most common of these missions is to retrieve something "lost to time", but there are other options. Changing an event or participating in some event in the past may be the event the Cosmic Mage decides must be done.
The PCs buy a Road Walker’s horse. It knows the way back home and might end up taking you part way there. They might then visit the past accidently, picking up clues that will help them resolve a future storyarc when they return home.
One of the PCs might be lead to The Road by a Goblin Guide, all in the attempt for them to find their father. Then they have to face down the monsters chasing him.