OnePager has always given users the ability to create charts that use a timeline layout instead of a Gantt chart, but in version 7.0, we’ve made it easier to do with just a button click.
Here is an example of what a typical project timeline looks like with multiple tasks aligned left-to-right:

Another popular type of timeline is what some people call birds on a wire, where multiple milestones sit on top of a line. This thin bar underneath the milestones represents a parent task from the WBS or the project summary task:

OnePager can also create hybrid timeline-Gantt layouts like this, with some items lined up left-to-right like a timeline, and others laid out in a waterfall like a Gantt chart:

In earlier versions of OnePager, all of the above charts were achievable, but not easily discoverable, especially by more casual users who didn’t know that the capabilities existed. In version 7.0, we’ve made the distinction between Gantt charts and timelines a lot more obvious so that users can switch back and forth with ease.
To change your chart layout, go to Home > Chart Properties > Rows/Swimlanes. Right at the top, you’ll see a section for Task Layout that lets you easily switch between a Gantt chart and a Timeline:

With a Gantt chart layout, every task gets its own row, so there’s not much else to consider. With a Timeline layout, you need to tell OnePager which field from Project or Excel you want to use to drive that timeline. Any tasks or milestones with the same value in that field will end up in the same row and lined up on the same timeline.
If you set up your timeline based on a field for which every single task shares the same value, you will end up with a chart that contains a single timeline with all tasks lined up left-to-right in just one row:

On the other hand, if you pick a timeline field that has different values for different tasks, you’ll end up with several timelines, one for each value in that field:

Timelines with Overlapping Tasks
Timelines always look best when all of the tasks are lined up sequentially and don’t overlap. Realistically, though, that’s not always easy to achieve. Sometimes, you have tasks that are concurrently scheduled because something didn’t finish on time.
This is where OnePager’s timeline layout can really be helpful, because we give you the option to either allow or avoid overlap, depending on the look you are trying to achieve. Under the Task Layout settings we discussed previously, there is an option to Stagger overlapping tasks:

If this setting is turned on, OnePager will automatically place conflicting tasks in their own rows to improve readability. If you have a lot of overlap, you will end up with a lot of staggering. If you have only a little overlap, OnePager may need to only add an extra row here and there. We’ll do this optimization for you. For a birds on a wire chart, it would look like this, with the milestones staggered below the parent task, since they would otherwise be sitting on top of each other. The milestones themselves don’t intersect, but each milestone does intersect with the parent task above it:

If you want to create a timeline no matter what, and you don’t care if things overlap, then leave this setting turned off. For the same set of tasks and milestones, here is how the chart will look with overlapping allowed:

If you are going to go for a timeline layout where you expect there to be some overlap, the other thing to keep in mind is that the text of your tasks and milestones can be a little harder to read. The best way to mitigate this is to increase the height of the rows in your chart (Home > Chart Properties > Page Layout). If there is enough whitespace above or below the tasks themselves, OnePager will automatically move your text into that available space, creating a much more readable chart, even when the tasks themselves are tightly packed.
How do i minimize space between row tasks. I have a lot of empty space between task rows and would like to create overall more space on gantt by reducing spacing between task bar rows.
The first thing to check is how your default row height compares to your task bar height. The default row height is set under Chart Properties > Page Layout, while the task bar height is set under Chart Properties > Task Bars. We recommend that your task bar height be about 80-90% of your default row height.
If you have rows in your chart that are completely empty, you can hide them by going to Home > Hide Rows.
If you have the baseline feature turned on, you can turn that off under Chart Properties > Task Bars, which will free up some vertical space as well.
Hopefully, these suggestions are helpful. If you have a specific chart where you need help reducing whitespace, it’s best to reach out to our support desk, as they are better-equipped to take a look at the specifics of your layout than we can through our blog comments.