Lean flow practice: breakdown lane

11May09

As I’m working on a presentation called “Urban Traffic: a Parable for Explaining Agile” (to be presented at XP Day 09 in Paris), I’m reflecting a lot behind the wheel these days.

Car stopped in breakdown lane

What is a breakdown lane for ? Building an extra lane on the side of the freeway is a big investment, so there must be a reason for it – and cars don’t break down that often, do they ? Why not avoid with the extra expense and build a smaller freeway, or just pack one more lane into the available space ?

Well, several reasons:

• Flow: on a freeway a breakdown lane is essential for stabilizing the normal flow of traffic.
• Safety: a breakdown lane improves safety for the driver of the broken down vehicle and for rescue services.

You can see the concept even more clearly with breakdown bays in tunnels, where the cost is huge! Apparently, stabilizing the overall flow capacity of the system is worth such an investment: you don’t want to lose a two-digit percentage of your flow capacity because of an out-of-gas car.

Back to Lean Management – here are some questions for your company:

• Where’s the breakdown lane in your enterprise processes? Do you have an ongoing lane or breakdown bays at specific milestones?
• Are stalled (non- or slowly moving) projects blocking other parts of the overall flow? How can you tell?
• Do stalled projects know they should pull over? How do they alert emergency services?
• How do you go about rescuing those vehicles and their drivers? How does this impact the flow of operations?

In Agile teams, blocked items get signalled very quickly (parked on the breakdown lane) and the flow of work is minimally interrupted, as team members move to getting another piece of work done (normal traffic) while the ScrumMaster picks up the impediment. This transparency and honesty sometimes puzzles managers who are more used to projects moving very slowly on the normal lanes. They might even get upset about the number of broken down vehicles (depending on the metrics they’re using, this is where ScrumMasters get yelled at). But once management understands Lean concepts, the advantage is clear and the flow picks up again – as it does when pulling away from a traffic jam!

PS: Traffic authorities in several European countries (where many freeways have only 2 or 3 lanes) have started allowing using the breakdown lane for normal traffic in case of saturation traffic jams, thereby temporarily boosting the local system capacity by 33-50%. But as soon as allow generalized driving on the breakdown lane, you’re back to significant potential blockage of your system – by just one broken down vehicle!

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