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Tuesday, October 11, 2011

Jetty Road traffic lights - an 'idle' threat?

The temporary traffic lights controlling traffic on Jetty Road in Drysdale are a foretaste of the future, when permanent traffic lights will control the junction of Jetty Road and Wyndham Street.

At present, motorists and cyclists in Jetty Road are having to contend with long delays, because the western side of Jetty Road has been closed while new stormwater drains are laid to take the run-off from the Jetty Road Urban Growth Area. The roadworks are forcing pedestrians onto the eastern side of the road that is, however, part-occupied already by contractors' vehicles.

Contractors Drapers have said that once the drains are laid, a new pavement will be laid on top of them and a new crossroads will be created where Jetty Road will meet Wyndham Street on its eastern side and the new dual-carriageway road into the Growth Area on its western side. The roadworks are meant to finish by Christmas, when the crossroads will be controlled by new - permanent - traffic lights.

On present plans, that dual-carrriageway road opposite Wyndham Street will be the Growth Area's only point of entry and exit for some years. Only later will it continue south through the Growth Area to join the Geelong-Portarlington Road. Until then, vehicles wishing to access the Geelong-Portarlington Road will have to do so by driving south down Jetty Road, increasing the present congestion in that road and at the ensuing roundabout.

Further, on present plans, that dual-carrriageway road won't proceed to the northern end of the Growth Area at all. That is why the City of Greater Geelong (the planning authority for the developoment) is supporting a proposed 'no limits' bridge to enable construction vehicles to access the northern end of the Growth Area from Bayshore Avenue and across Griggs Creek. If that bridge is built, residents can look forward to still-greater congestion on Jetty Road as construction vehicles go up and down it carrying machinery and dirt into and out of the northern end of the Growth Area.

Traffic lights an environmental problem, say researchers
The City of Greater Geelong is installing traffic lights in Jetty Road just as other cities and communities are realising the economic and environmental costs of traffic lights and replacing them with roundabouts. The Drysdale & Clifton Springs Community Association's Neil McGuinness has been reading the research and doing some calculations - here are the results.

Traffic should only have to stop to accommodate pedestrians, not to control traffic flow. Traffic lights are designed to bring traffic to a stop. Drivers then wait for the lights to change and, as they wait, their vehicles idle, polluting the atmosphere and contributing to climate change. When the lights change, drivers accelerate their vehicles to cruising speed, using more fuel than they would if they'd maintained their crusing speed and, therefore, creating more pollution than they would if they hadn't had to stop in the first place. Roundabouts, in contrast, keep traffic moving - perhaps moving slowly, but still moving.

An imaginary intersection
Let's assess the problems associated with traffic lights by conducting an 'environmental audit' of an imaginary intersection controlled by traffic lights. Let's start by making some assumptions about usage and time. Let's assume that between 7.00 a.m. and 7.00 p.m., an average of 10 vehicles pass through the intersection each minute (i.e. an average of 600 vehicles/hour); and that each vehicle has to wait at a red light for an average of 30 seconds. On the basis of those assumptions, we can say that our imaginary lights-controlled intersection creates 60 hours a day of 'wasted' waiting time:
600 vehicles/hour x 12 hours x 30 seconds = 3,600 minutes, i.e. 60 hours a day of 'wasted' waiting time.

Now let's make some some assumptions about fuel costs. Let's assume that, on average, a stationary vehicle with its motor idling uses approx 1.5 litres of fuel per hour (i.e. 0.025 litres/minute) and that fuel costs $1.45 a litre. Thus, the cost of idling is approximately 3.6c/minute. (Fuel usage will depend, of course, on the vehicle's engine type, size and efficiency.) Now, let's add our assumption that our imaginary lights-controlled intersection 'wastes' 3,600 minutes a day. On the basis of those assumptions, we can now say that our imaginary intersection 'wastes' $129.60 in fuel a day:
3,600 minutes/day x 3.6c/minute = $129.60.

Finally, lets make some assumptions about the pollution costs of our imaginary lights-controlled intersection. Let's assume that each litre of fuel produces, when it's burnt, 2.4kg of carbon dioxide; that a stationary idling vehicle uses approx 1.5 litres per hour of fuel (i.e. 0.025 litres/minute); and that our imaginary lights-controlled intersection creates 3,600 minutes (60 hours) a day of 'wasted' waiting time. On the basis of those assumptions, we can now say that our imaginary intersection creates 216kg of carbon dioxide a day:
3,600 minutes/day x 0.025 litres/minute x 2.4kg = 216kg (0.216 tonnes).

The proposed Carbon Tax will assign Carbon Dioxide a value of $23 a tonne. On that basis, our imaginary intersection will cost us all $5.40 a day on top of the wasted fuel costs: 0.216 tonnes x $23/tonne = $4.97

In summary
On each day, our imaginary intersection controlled by traffic lights has these costs:
  • 60 hours of 'wasted' waiting time
  • $129.60 of 'wasted' fuel
  • 216kg of carbon dioxide
  • $4.97 of carbon tax.
You can use these assumptions and calculations to conduct your own audit of a real intersection controlled by traffic lights; and if you do that at each such intersection on your route to and from working, studying, etc., you can estimate the environmental costs of your daily commute. (It will give you something to do as you sit at the traffic lights!)

Once you've costed your commute to and from work, you can speculate on the likely environmental impact of new developments in Drysdale, such as the Jetty Road Growth Area and Central Walk. Neither of those developments is accompanied by any plans to create jobs locally for their residents. Consequently, each development will make Drysdale even more of a 'dorimitory town' for Geelong and Melbourne, as new residents are forced to commute there for work; and each new commuter will have their environmental impact increased by each intersection on their route that is controlled by traffic lights! Those impacts will start with the traffic lights in Jetty Road.

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