Stumped

I've never been quite convinced that Winnipeg Transit's Navigo feature always provides the best trip results from point-to-point. So from time to time, when planning a trip, I engage in a solitary game of "Stump Navigo" where I try to find a better route than the options given. Until today, my efforts hadn't met with any success, but after seeing a list of 2-transfer trips that would have taken north of the Assiniboine, down Portage, for a trip to the doctor (from Point A to Point B) that needn't have crossed any river at all, I was convinced that I could do better. So I did some sleuthing, found out I was right, and wrote a letter.

This isn't the first time I've written a letter (OK, email) to Winnipeg Transit officials. When I was in high school, the paper transfers that you would receive when paying with a ticket had facts about the city on them (how many kilometres of streets, number of trees the city maintained, etc.) When I was in Grade 11 or 12, the facts were discontinued. I emailed to ask why, and I was referred to the designer. Perhaps this letter will receive a more interesting response.

I think, in the back of my mind, I was inspired by this book that my brother owned which is a collection of letters and responses, written mostly to hotels and airlines, on the most inane topics that often resulted in the letter-writer receiving free stuff. I have no such expectations.

Here is my email. I just sent it so I am awaiting, and am currently awaiting a response:

A comment and a question:

The comment first. I'd just like to say that I really appreciate the Navigo feature of the transit website. It makes life whole lot easier than those days when I'd have to make 3 or 4 telebus calls to plan the best trip. I've noticed incremental improvements over the last several years, none more vital than the "leave right away" feature. The utility of Navigo is approaching that of the site I used while living in Holland (www.9292ov.nl)

Now the question:

As a former computer science student, I'm curious how various trip options are ranked and selected for the 'top 5'. I'll provide you with a concrete example. I was investigating a trip from my address (removed) to 3318 Roblin Blvd, leaving at 18:48. The options given were


Intuitively, I thought the best trip would be to board a south/westbound 18 bus, disembark at Corydon and Edgeland, and the continue on the 79. Searching the two legs separately, I found that I could ride the 18 from Osborne/River to Corydon/Edgeland between 18:49 and 19:08, wait twelve minutes, and ride the 79 from Corydon/Edgeland to my destination from 19:20-19:26. It would seem this option is preferable to all of the options listed except possibly Option 3, which is faster by 2 minutes (for all others, my proposed trip has a shorter total trip time, less walking and fewer transfers than #2 and #3). Or does your algorithm seek to minimize waiting time (at 12 minutes, my trip would have the longest wait)?

Obviously an algorithm that exhausts all the trip possibilities and selects the best would be too expensive. Is my trip simply one of those that slips through the heuristic cracks?

All the best.

I'm sure it's a coincidence, but I haven't been able to connect to Navigo since I wrote the email.

Update: See my questions answered above.