Performance and Operation of the Bridge
  West Gate Bridge
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West Gate Bridge as seen from Hyde St.
February 2008
 
     
     
 

The West Gate Bridge is one of Melbourne’s most important pieces of transport infrastructure, and a well-organised operation is required in order to keep the bridge performing effectively. To achieve this, many safety initiatives were introduced along the bridge, including variable speed limits and emergency telephones, ensuring that motorists can cross the bridge in a safe and efficient manner.

The bridge historically performs well in its task of moving traffic from the Melbourne central business district to the western suburbs and beyond, but as traffic volumes increase each year, the bridge is beginning to carrying more traffic than first anticipated in the 1970’s.

 
   
     
  Contents:  
     
     
  Classification & Management History
The West Gate Bridge is managed by the Roads Corporation, more commonly know by its trading name Vicroads, since 1989. All operational matters is the responsibility of Vicroads – aspects including maintenance and traffic management. Vicroads classifies the West Gate Bridge as SN6225 (Vicroads, 2007).

Historically, the bridge was managed by numerous organisations:
  • Lower Yarra Company Limited (private company, 1961 - 1962);
  • Lower Yarra Crossing Authority (state government statutory body, 1965 – 1974);
  • West Gate Bridge Authority (state government statutory body, 1974 – 1982);
  • Country Roads Board (state government department, 1982 – 1983);
  • Road Construction Authority (state government department, 1983 – 1989).
The bridge carries the West Gate Freeway (Freeway #1820) for its entirety.
 
   
     
  Pay as you Go: The Bridge Toll
The West Gate Bridge operated as a toll facility from 16 November 1978 to 15 November 1985, collecting a total of around $10 million (1985 figures) in which was used by the state government to recoup the cost of construction and associated operational costs (Road Construction Authority, 1985). The tolls were collected at toll booths operating on the eastern side of the bridge at the now service centres at the Todd Road exit.

Between November 1978 and November 1979, 7,409,682 vehicles had cross the bridge, bringing in $2,943,573 to the West Gate Bridge Authority, the statutory body which managed the bridge between 1978 and 1982 (West Gate Bridge Authority, 1979). The toll for light vehicles was 60c, and slightly higher for heavy / commercial vehicles, all of which would assist to pay off the bridge within 40 years. The toll for a normal ‘light’ vehicle was reduced by 10c in early 1979, but this only benefited regular motorists who bought pre-paid toll vouchers. This toll was once again reduced to 45c on October 1 1979. Overall, the average toll for all classes of vehicles (light and heavy) was 65c over the 1978/79 financial year (West Gate Bridge Authority, 1979).

By the end of 1981, $5,845,274 was collected in that year alone, signifying a 15.4% increase from the same period a year before (West Gate Bridge Authority, 1981). The West Gate Bridge Authority was “confident that associated with growth in traffic volumes, revenue will also continue to grow strongly” (West Gate Bridge Authority, 1981, pp. 3). The management of the bridge, as well as the financial responsibilities, was transferred to the Country Roads Board in 1982, thus ending the operations of the West Gate Bridge Authority.

On 15 November 1985, tolls were abolished and the remaining costs were covered directly by the State Government.

Table 1. Toll Revenues from 1979 to 1981. Source: Compiled from West Gate Bridge Authority Annual Reports 1979-1981.
 
 
Year Ending Tolls Collected # No. of vehicles
1979 $2,943,573 7,409,682
1980 $5,065,237 8,727,377
1981 $5,845,274 9,722,548
 
  # - $ amounts are figures as of that year  
     
 
Westbound at Todd Road.
January 2005.
 
 
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  Wind Effects on Traffic
Since the opening of the bridge, traffic across the bridge is subjected to variable speed limits to ensure that high vehicles are not overturned by gusts from strong winds. Models were produced to test the effect on vehicles, and to establish speeds to ensure a safe crossing. The tests concluded the following (Balfe & Toaklet, 1986):
  • An increase in the forward speed of the vehicle in combination with the cross wind increases the instability of a vehicle;
  • If the speed of the vehicle equals the speed of the cross-winds, there is a 40% increase of the drag force on the vehicle. The drag force (from the cross-winds) on the vehicle contributes in an event of an overturning;
  • Vehicular speed limits must be imposed at times of high cross-wind speeds.
Table 2. Cross-winds speed likely to case overturning. Source: Balfe & Toaklet (1986).
 
 
Vehicle Description Wind Speed (m/s)
High van * Empty 40
Laden 60
Sedan / Station wagon Motor Car Empty 60
Laden 70
Box Bodied Truck Empty 50
Laden 100
 
  * Very light and tall van configurations might overturn in wind speeds of 35 m/s.  
     
  The following speeds were recommend restricts to be applied:

Table 3.
Recommended speed limits recommended to the West Gate Bridge Authority prior to the opening of the bridge. Source: Balfe & Toaklet (1986).
 
 
Wind Speed Range (km/hr) Restrictions
Mean (average over 5 mins) Gust (maximum indicated by instruments)
Less than 50 Less than 80 No restriction on account of wind conditions.
50 to 60 80 to 100 Speed limit 60 km/hr.
60 to 70 100 to 120 Speed limit 45 km/hr
70 to 90 120 to 150 Speed limit 30 km/hr.
Restrict traffic to two inner lanes each way (preferably separated). Prevent passage of caravans and light high-sided vehicles (include vehicles with luggage on top).
90 to 120 150 to 200 Speed limit 5 km/hr.
Restrict traffic to one inner lane each way. Progressively prevent passage of all high-sided vehicles (include vehicles with luggage on top).
Greater than 120 Greater than 200 Prevent passage of all vehicles
 
     
  The wind speed is measured using instruments located on the same level as the road deck. A change in speed limit (the bridge is designated at 80km/h) was historically indicated by flashing lights. The actual speed restrictions that were imposed were:
  • Amber light indicated the speed of 60km/h;
  • A red light indicated the speed of 40 km/h.
 
     
 
Variable Speed Limit eastbound on bridge.
January 2005.
 
   
  Usually, if the speed limit was 40 km/hr, the outer lanes would be closed, and high vehicles would be banned from crossing the bridge. The flashing lights were modernised by the introduction of LED variable speed limit signs in 2003 (The Age, 2003).

The West Gate Bridge has been closed in the past due to strong cross-winds, one example is on September 4 2002 where strong winds blew a truck onto its side, causing minor injuries to the driver (The Age, 2002).
 
 
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  Traffic Volumes
The West Gate Bridge is the most significant western crossing of the Yarra River from the Melbourne central business district (CBD), and as a consequence, carries large volumes of traffic which has gradually increased each yeah since the bridge’s opening.

The bridge’s opening on the 15th November 1978 (West Gate Bridge Authority, 1979) coincided with the massive freeway building program that the state of Victoria was undertaking in the 1970’s. The West Gate Bridge and the West Gate Freeway was another piece of the ‘jigsaw’ designed to reduce traffic times to Geelong and take traffic away from Princes Highway West and Footscray Road, both which had seen unprecedented congestion.

Upon opening, the bridge was designed to carry 40,000 vehicles a day (The Age, 2007). In the first year of operation, an average of 24,700 vehicles a day were using the bridge. By the start of 1981, this number had risen to 29,602, an increase of 17.9% from the previous year (West Gate Bridge Authority, 1981).

By 1994, the morning peak period carried 17,627 vehicles alone (The Age, 2005), just short of the daily traffic volume of when the bridge was first opened. This substantial growth did not affect the overall free-flow of traffic across the bridge, as it took 11 mins to travel between the Western Ring Road and Kings Way (Princes Highway East) at an average speed of 80.7 km/h.

Ten years later in 2004, the morning peak traffic had increased to 20,806 (The Age, 2005), with the overall daily traffic peaking at 155,000 vehicles, more than four times what the bridge was designed to carry. The average speed dropped to 49.6 km/h and the same trip now took 25 minutes, 14 minutes longer compared to 1994. At the current rate of growth, traffic would expect to reach 200,000 vehicles per day by 2021 (The Age, 2007).

The bridge is a victim of its own success, with calls now for a second freeway crossing of the Yarra River, either as a second bridge or as a tunnel (The Age, 2007); while others call for improvements to the public transport network as a more efficient solution to combat increasing traffic.
 
 
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  Bridge Utilities / Safety Initiatives
In order to ensure that the West Gate Bridge is free-flowing as possible, many safety initiatives have been installed.

Emergency Telephones and Breakdowns

There are 106 emergency telephones (Road Construction Authority, 1984) along the bridge, all connected to the Vicroads Traffic Management Centre. A response vehicle will be dispatched to assist in an event of a breakdown.

Traffic Barriers
The edge of the bridge is protected by a railing which consist of three 152 mm x 64 mm x 4.78 rectangular sections spaced vertically every 0.44 m. The median railing is 152 mm x 76 mm x 6.4 mm vertically spaced at 0.43 m (Balfe & Toaklet, 1986). All railings are made of steel hollow tubes.
 
     
 
Eastbound on the bridge, with crash barriers visible.
January 2005.
 
 
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  References:  
  Balfe & Toaklet (1986). Redesign of West Gate Bridge. Road Construction Authority, Melbourne.

The Age, 2002 . “Clean up begins after winds wreak havoc” . 4/10/2002 (Online) Available from: http://www.theage.com.au/articles/2002/09/03/1030953453897.html, visited 4/4/2008.

The Age, 2003. “Speed cameras for West Gate Bridge”. 1/4/2002 (Online) Available from: http://www.theage.com.au/articles/2003/03/31/1048962699770.html, visited 4/4/2008.

The Age, 2005. “West Gate stalling city traffic flow”. 3/10/2005 (Online) Available from: http://www.theage.com.au/articles/2005/10/02/1128191610133.html, visited 4/4/2008.

The Age, 2007. “West Gate a 'disaster' costing millions”. 16/12/2007 (Online) Available from: http://www.theage.com.au/articles/2007/12/15/1197568332255.html, visited 4/4/2008.

Road Construction Authority (1986). ‘The end of tolls on West Gate Bridge’. Roads Victoria, January/February, 4(1), 12

Vicroads (2007). VicRoads - Register of Public Roads (PART A). Available from: http://www.vicroads.vic.gov.au/NR/rdonlyres/36914600-893E-4379-9AD5-EA04905187D3/0/ROPR_June2007.pdf, visited 4/4/2008.

West Gate Bridge Authority (1979). West Gate Bridge Authority 14 th Annual Report – 1979.

West Gate Bridge Authority (1980). West Gate Bridge Authority 15 th Annual Report – 1980.

West Gate Bridge Authority (1981). West Gate Bridge First Annual Report 1981.
 
     
 
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