My generalized staff scheduler is a small optimization problem: eight people, a week of half-hour slots, about five thousand binary variables. By modern standards that is tiny. So when it started taking minutes to solve — or worse, returning nothing at all — my first reaction was disbelief. This post is the story of CBC vs HiGHS on that exact model, and the four fixes that actually mattered. If your PuLP + CBC model is grinding, some of these will probably apply to you too.
Continue reading “Why a Tiny Scheduling MILP Took Minutes: CBC vs HiGHS”Tag: operations research
From One Client’s Rules to Any Team: A General Scheduler
The staff scheduler I built for that Fiverr client did exactly one job. It knew about his clients, his courses, his equipment, his week. It was a good staff scheduling model for precisely one business on Earth. Every sheet name, every constraint, every assumption was his. When I put it online I knew the truth: nobody else could use it without hiring me to rebuild it. So I rebuilt it once, properly, for everyone. This is how the generalization went.
Route4Me Alternative: A Free Optimizer, No Sales Call
If you’ve tried to get a straight price out of Route4Me, you’ve probably hit a “contact sales” button instead of a number. That’s the most common complaint I hear, and it’s usually why people start searching for a route4me alternative in the first place. I’ve spent twenty-plus years building routing and scheduling optimization for a living, so I built a free one for the operator who just wants to run a route, not book a demo call first.
RouteXL Alternatives: Free Multi-Stop Route Planners
I spent twenty-plus years building vehicle routing models for companies that paid serious money for them, so when I went looking at RouteXL alternatives recently, I wasn’t shopping — I was checking out the neighborhood. RouteXL is probably the best-known free multi-stop route planner on the internet, and for good reason: paste in your addresses, get them back in a sensible order, free up to 20 stops. But 20 stops is exactly where a lot of real delivery days start, and that’s where the free tier ends. This post is an honest tour of what’s out there — including the free VRP tool I built and run myself — and which one fits which kind of routing problem.
Twenty Years of Models, One at a Time
I’ve been doing operations research for over 20 years. Most of what I’ve built is locked inside Excel files on a hard drive. Not because Excel is where OR models belong — it isn’t, really — but because that’s where the data was, that’s where the clients were, and that’s what worked at the time.
The backlog is real. Staff scheduling, vehicle routing, warehouse slotting, least-cost formulation, a few others. Each one took months to build and calibrate. Each one is doing nothing right now except existing as a .xlsm file.
