Ongoing study confirms no Clearway benefits

Tram Travel Time Saving Narrows: 7 Seconds in Sydney Road_MG_4929

An update to a PTUA travel time study has confirmed an earlier finding that extended clearway hours on Sydney Road in Brunswick have not noticeably improved tram travel speeds.

Earlier results obtained in November last year, after 5 months of study, found that after clearway times in Sydney Road were extended from 6pm to 7pm, average travel times for trams heading out of the city during these times improved by just 14 seconds on the 2.5km to Moreland Road.

At that time, however, police were not actively enforcing the new clearway times. But observations continued to be made, and earlier this year police commenced enforcement. Accordingly, the results were re-evaluated by adding the most recent five months’ observations to those already taken.

The result? The mean improvement in travel time is now 7 seconds, not 14–from 9 minutes and 12 seconds to 9 minutes and 5 seconds.

“It really confirms what we found earlier: that whatever the actual difference is, it’s not statistically significant, and so is going to be lost among the chance variations that occur in travel times anyway,” said PTUA Secretary Tony Morton, who conducted the study. “We might take another year of observations and find the difference is 10 seconds, or 5, or 15, but the point is it’s effectively a random number.”

Results for other peak hour travel times on the route 19 tram were also virtually unchanged from the earlier findings. In particular, the Royal Parade section of the route is still marginally slower than the Sydney Road section in peak hour, despite trams in Royal Parade having a dedicated lane. Meanwhile, the ‘dead time’ spent waiting at red lights has barely changed–on Sydney Road in the evenings, it actually increased slightly.

“The results came as no surprise to us,” Dr Morton said. “Anecdotally, I’d observed last year that even though the clearways weren’t actively enforced, people weren’t parking in them after 6pm. I’d only see the occasional parked car, and the trips where I saw parked cars weren’t noticeably slower.”

“It underscores once again our main message: tram delays are primarily about lack of priority at traffic lights, and only secondarily about traffic congestion,” Dr Morton concluded. “In Zurich, when they were considering how to speed up trams back in the 1970s, people feared that introducing traffic light priority would be unpopular and slow down motorists. Now it has the most successful priority scheme in the world, which doesn’t even slow motorists down that much. Based on their experience, we have little doubt that traffic light priority would go down better with the general public than clearway extensions.”

Summary of Results: March 2010 update

Location, time and direction time (min:sec) Av. speed (kph) Av.dead time (min:sec)
Sydney Road, PM northbound, May–June 2009 9:12 16.3 1:19
Sydney Road, PM northbound, July 2009–March 2010 9:05 16.5 1:31
Royal Parade, PM northbound 10:30 15.4 2:19
Sydney Road, AM southbound 10:08 14.8 1:56
Royal Parade, AM southbound 11:36 14.0 3:05

Observations were collected between 25 May 2009 and 15 March 2010. AM observations were collected between 8am and 8:30am. PM observations were collected between 6:00pm and 7:00pm.

The difference of 7 seconds between mean travel time in May–June and in July–November has a t-statistic of 0.425. The null hypothesis–that the true mean travel time is the same before and after the clearway extension–is not rejected at the 80% level. The median travel time, at 9 minutes, is identical before and after the clearway extension.