An Australian government report urges a 6.5km (4mi) long tunnelway to Sydney's Warringah peninsula in the northeast of the metro area. The conservative Liberal Party opposition in the state of NSW has said it will make support for the investor-financed project a priority in its election campaign later this year, while the state Labor Government is expressing skepticism about the financability... MORE
An Australian government report urges a 6.5km (4mi) long tunnelway to Sydney's Warringah peninsula in the northeast of the metro area. The conservative Liberal Party opposition in the state of NSW has said it will make support for the investor-financed project a priority in its election campaign later this year, while the state Labor Government is expressing skepticism about the financability of the proposal. The project has no accepted name yet. It is sometimes called the Northern Beaches Tunnel, and sometimes the Spit Tunnel because it would supplement the main Spit Bridge over Middle Harbour.
In one configuration dubbed Option A by the latest report it consist of 6.5km (4mi) of tunnels. It would descend underground from north of the Spit Bridge in Seaforth and Balgowlah, then go the 700m (2300ft) under the water of Middle Harbour and under the suburbs of Mosman, and North Cremorne to join the long-established Warringah Freeway with four direct connector ramps emerging from portals.
The Freeway in turn connects south to the Harbour Bridge and Harbour Tunnel close by the central business district and via the Eastern Distributor to the airport. The Warringah freeway links westerly to the Hills Motorway tollroad and northerly to the Pacific Highway.
As its name implies the Warringah Freeway was originally intended to extend to the Warringah Peninsular, but never made it. There were plans in the 1960s for a surface motorway through Northbridge and Castlecrag and a grand new bridge over Middle Harbour into the Warringah Peninsula, but they fell foul of local opposition. The success of a pair of toll tunnels on Melbourne's CityLink, a toll tunnelway on the Eastern Distributor to Sydney airport, and a long non-tolled tunnelway on the M5-East has led to deals with investors to build a tolled Cross City Tunnel and a tunnelway at Lane Cove, and planning for tunnel-highways for the M4 west of the CBD, and another to link the M2 to the F3 in northern Sydney.
Including the strictly underwater Harbour Tunnel, this would be Sydney's eighth major road tunnel project, making it one of the world's most road-tunneled cities, along with Hong Kong and Oslo.
The recent government study also looks at an Option B for the Warringah link – a shorter approx 4km (2.4mi) tunnel under Military Road, the most crowded surface arterial in the suburbs of Mosman and N. Cremorne. It would link with an upgrade of the existing Spit Road and the Spit Bridge. That is a 2x2-lane bascule or liftspan with weekend openings for yachts, averaging about 10/day, and great backups for weekend visitors.
The Warringah area of some 263km sq (101sq mi) consists at its southern end of the older 19th century suburb of Manly on the northern head of Sydney harbor. Because of the heavily indented coastline of the harbor it is connected to central Sydney mostly by harbor ferries. The rest of the 260k population area developed in the 20th century as weekender, retirement, and beach resort homes. In the past couple of decades more working people have moved into the area to live. A lot of the peninsula is rugged terrain and it is separated from the rest of the metro area by Middle Harbour and parkland containing deep gorges. Outside wildlands in permanent reserves the area is largely developed and is gaining population at a lesser rate than the 3.9m total Sydney metro region.
The area has only three road access points, no rail, and ferries Manly to the CBD's Circular Quay. Ten percent of commuters have jobs in the CBD and of these 60% use bus or ferry. Total job journey mode split is 80%-car/20%-transit with about two-thirds of jobs being within the Warringah region itself, one third outside it, but less than a third of those downtown. Military Road, the major link to the rest of the metro area runs 800 buses/day. There is increasing congestion on teh approaches to the peninsula at weekends due to the attraction to people from the west of the beaches, the parks and the extensive estuarine inlets.
Traffic speeds lower than free flow or posted limits occur for extensive periods during the day and weekends, the report notes. Ten signalized arterial lanes constitute the total link with the rest of the metro area so there is heavy overloading. In the morning peak on Spit bridge and Military Rd the average speed is 21km/hr (13mph). Speeds in non-peak periods are around 40km/hr (25mph).
Recommending the tunnelway, the government report says: "The road tunnel strategy would improve travel times from Manly north and provide a bypass of the Mosman/Cremorne area for through traffic, including trucks and potentially some buses. It would enable surface route changes that favor public transport (transit), local accessibility, urban amenity and improved safety. Bus services could also be reconfigured or expanded, with an increase in the number of through-express buses from the Northern Beaches." (ES-xiii)
North of the Spit Bridge and proposed tunnel the major way into the northeastern suburbs continues on an existing stretch of isolated motorway with the great name of the Burnt Creek Bridge Deviation. It opened in 1985.
Sydney University's Institute of Transport Studies in subcontracted work projected overall improvements of trip times of about 7% and benefit/cost ratios of 5:1 for Option A. The cheaper Option B with the shorter tunnel has a B/C of 6.4. Present net value of Option A is $1.8b and Opt B $1.6b. At a toll of about $2 (A$3.50) the longer Opt A would require a public subsidy of $160m (A$290m) while Opt B could be built by investors entirely on their own coin. If higher tolls were allowed both schemes might benefit taxpayers - by attracting a franchise fee in the case of Opt B and being self-sufficient in the case of Opt A.
The report favors tolling, not only to generate funding for the road improvements, but also to make efficient use of roadways and to manage traffic. (p30)
"It follows that tolling of major new capacity increases can be effective in encouraging the efficient use of a new facility and in minimising induced travel demand (as well as funding or helping fund the new facility). Sydney residents are accustomed to tolling of new facilities. An issue with pricing of new capacity is that the price may be greater than the cost of using the facility at particular times of day. For example, the costs of using an uncongested road tunnel around midnight on a weekday may be no more than the tunnel operating costs. A toll that is higher than this might deter some who would otherwise use the tunnel, with a resulting loss of efficiency in economic terms. This can be addressed by reducing the toll in low demand periods."
Variable toll proposed
"A variable tolling structure, ie with a premium charged for travel in
the peak, would be likely to maximise revenue and minimise any cost to the
public sector. It would also help to ensure that the new infrastructure did not
add to peak period congestion on the Warringah Freeway, minimising any
additional traffic induced by the improved road conditions." (ES-xiv)
The report also favors detailed consideration of a "highspeed public transport service" on a dedicated right of way, either a rail line or a busway, separate from the proposed tunnelway. However it cautions that transit will not relieve road congestion significantly and estimates the cross-elasticity of car demand with respect to transit costs is less than 0.1. (So a 50% reduction in transit fares would reduce car traffic by less than 5%.)
"It is very difficult to attract car travellers to an improved public transport service in sufficient number to make significant inroads into road congestion."
In addition to smoothing car flow, the report says, the tunnelway would improve conditions significantly for buses in mixed lanes. It would allow new express bus service to the further suburbs and improved local bus service using surface routes freed from through-traffic.
Middle Harbour has 25m (80ft) of water where the tunnel would go. The proposed route for Opt-A is 7.6km (4.7mi) including open ramps, and would provide 2x2-lanes with a maximum grade of 3% to allow trucks and buses to maintain a good speed uphill. Design speed in the tunnels would be 80km/hr (50mph).
The cheaper Opt-B involving upgrade of the existing bridge and only an under-ground tunnelway has tunnels plus ramps of 5.1km (3.2mi). It requires grade separation of a major signalized intersection at Sydney Road. The Spit Bridge would be widened to 6-lanes and permanently closed to boat traffic. The bridge's 6-lanes carrying local as well as through traffic would have a movable barrier for 4/2, 3/3, and 2/4 lane operations.
The route has relatively good tunneling rock. Cost of the tunnels for twin 2-lane tubes are estimated at $190m (A$340m) for the longer Opt-A and $70m (A$107m) for the shorter Opt-B. Total construction costs including surface works are $525m and $360m. Annual operating costs would be about $10m/yr. The report says these costs are based on recent experience in tunneling in Sydney.
Average trip times on teh new links are projected as 5.7min versus 14.2mins now, with a speed of 80km/hr vs 35km/hr now. Tunnelway traffic is forecast at 52k/day in the first year with travel time savings worth $140m based on $8.60/hour value of time saved. The report calls the project "highly economically viable." (p48)
Based on a $2 (A$3.50) toll revenue is put at $36m in the first year. Growth would be modest thereafter.
An opinion survey in the area found 42% see road congestion as the major problem for residents compared to 12% wanting more transit. However there was support of 64% of people for better traffic management over simply expanding road capacity. The report found a warrant for a dual approach of road and transit improvements with tolls used to manage traffic.
The report is called "IMPROVING TRANSPORT ON THE WARRINGAH PENINSULA: ISSUES AND OPTIONS" Working Paper 53. Bureau of Transport and Regional Economics, Canberra, 2003 www.btre.gov.au TRnews 2003-06-05
