Austin's Award-Winning Rapid Bus Signal System Only Works 15-20% of the Time

Apr 2, 2015

Austin's bus system got two new lines last year, called MetroRapid. They're generally larger, run more frequently, have fewer stops (to run faster) and offer some amenities not found on the city's local buses, like WiFi. More than a million trips have been taken on the new rapid bus lines. They also have a higher price: A ride on one of Capital Metro's MetroRapid buses costs $1.75, as opposed to $1.25 for a ride on their local alternatives. 

But these rapid buses supposedly justify that higher price by getting you around faster. Capital Metro labels it a "premium" service, and one advantage they're supposed to have is they can hold green lights longer at intersections outside of downtown, extending the time before a light turns red and allowing the rapid bus to get through in time. "Special technology allows all MetroRapid vehicles to catch more green lights to stay on schedule," Capital Metro says on its website.

The system is called "Transit Signal Priority" (TSP), and it's the first of its kind in Texas. This week, it received a "Gold" Texas Engineering Excellence Award from the American Council of Engineering Companies. The award is touted on the city's website and social media accounts, but the problem is, the system's not really working as it should, and the rapid buses are running slower — and later — than Capital Metro planned for. 

"We have some lingering challenges. The on-time performance is not as good as we had hoped," Todd Hemingson, Vice President of Strategic Planning and Development at Capital Metro, said in a recent presentation on the signal system at a University of Texas at Austin transportation conference. "It's partly a function of congestion in the four corridors we're serving. Our travel times have ended up being longer than we anticipated." 

Part of the reason for that is that the two new rapid lines were modeled and planned based on 2008 traffic data; the corridors the MetroRapid 801 and 803 routes travel (North Lamar/South Congress and Burnet/South Lamar, respectively) have become much more congested since that time, according to Hemingson.

Capital Metro's signal system is supposed to allow its rapid buses "to catch more green lights to stay on schedule," according to its website. But it only works 15-20% of the time.
Credit Todd Hemingson/Capital Metro

Another issue is that one of the speed advantages singular to the rapid buses — those extended green lights — is only working 15-20 percent of the time. 

Each time a rapid bus approaches a signal at an intersection, it sends a message to the Transit Signal Priority system, basically saying, "I'm here." And every day, Hemingson said, there are between 2,400 and 3,000 "check-ins," where a bus approaching a signal about to turn red pings the system and asks it to extend the green light. (The system doesn't apply from Cesar Chavez to Martin Luther King Boulevard, as there is a bus priority lane in that section of downtown.)

But of those up to 3,000 "check-ins" a day, the signal is extended for only about 275-450 of those requests, or 15-20 percent of the time.

"Basically," Hemingson said, the system is telling the buses, “you don’t qualify” for an extended green. Hemingson said the intersections are either not at the right point in the signal phase (with the green soon turning to yellow), or buses are too far away from the signal (the green can be extended only about six seconds). The way the system's currently set up, neither drivers nor riders know if the bus is getting a longer green.

Part of the issue, Hemingson said, is that you have two different systems — and in some ways, two different ways of thinking — trying to get on the same page: transit engineers and traffic engineers. (To illustrate this point, Hemingson showed a slide of a hockey game fight.) Bus engineers want to get buses through as quickly as they can. Traffic engineers want to do the same for cars. So there's "business rules" for whether a bus gets an extended green that both the city and Capital Metro had to agree to, and those rules currently mean buses only get extended greens a fraction of the time they should. 

Another issue is traffic congestion during peak travel time hours, which can render the extended green signals useless when traffic backs up for blocks. "If it's stop-and-go, bumper-to-bumper, then [the system] isn't going to be much help." 

Hemingson wants to make the system better by doing a deep analysis of the data they have on the system, likely with the help of UT Austin's Center for Transportation Research, so if the data shows a way to get more rapid buses more extended greens, tweaks could be made. "We have reams of data," Hemingson said, "but we don't really have the resources internally [at Capital Metro] to really dig through it and understand it." 

Hemingson also wants to explore other ways to give buses an advantage at intersections. One idea, called "queue jumper," is similar to the current signal system — it would give buses an early green at intersections while cars still have a red. 

“This project is a cutting edge example of what can be achieved through a public-private partnership,” City of Austin Chief Information Officer Stephen Elkins said in a press release announcing the award for the Transit Signal Priority system. “We hope this can serve as a roadmap for future solutions to challenges the City is facing.”

Capital Metro, however, says there's a long way to go before the system is working as well as it could be.