Recent reports regarding modifications to Sydney’s CBD and South East Light Rail (CSELR)project have highlighted two aspects announced by the NSW Minister for Transport – the move to longer trams and the removal of the World Square stop. These are contained in the CSELR Modifications Report  (MR) released this month, but other aspects of the report make for interesting reading.

First the headline items. The original approval proposed vehicle specifications were for light rail vehicles (LRVs) with a capacity of 300 people that were 45 metres long, among the longest single unit articulated trams available. Although the MR describes the replacement vehicles as even longer at 67 metres, it appears that these will actually be made up of two coupled units of 33 metres each. Single tram units of this length are quite common and similar in size to the new rolling stock on the current light rail line. Running two such units coupled together is also common practice world wide.

The double units will carry up to 466 passengers. The previous approval planned for initial frequencies of three minutes in the CBD in peak periods and six on each of the two branch lines; the modification report proposes slightly lower frequencies, with trams running at four and eight minute intervals respectively from 7:00am to 7:00pm (see table). However with the longer vehicles this means that almost 7,000 passengers rather than 6,000 can be moved in peak hour in each direction. This is an increase of 16.5%, with the MR suggesting a possible 20% increase in future potential capacity from using the longer LRVs.

CSELR frequencies (from the Transport for NSW CESLR Modifications Report)

There are other advantages to the longer option. The first is greater flexibility, especially  for Connecting Sydney, the consortium that has won the contract to operate the new line also takes over operations of the existing Dulwich Hill line next year. Platforms on this line can accommodate a maximum of 33-metre LRVs only and while it has its own recently-acquired fleet, the new operator would be able to use the CSELR rolling stock in future on this line as single uncoupled units. It may also make it easier for CSELR vehicles to access the maintenance depot for both lines to be constructed at Rozelle on the Dulwich Hill line, as they could travel over this line uncoupled.

There are some disadvantages, though. The new vehicles will take longer to traverse intersections and pedestrian crossings. There may be safety issues with a single driver having to manage passenger movements on and off the coupled trams, not to mention security concerns if the trailing LRV unit is completely unstaffed. In addition most of the platforms along the route will have to be lengthened to accommodate the proposed LRVs, though the 90-metre platforms at Central and Moore Park designed for special events will be reduced to 75 metres.

The other item that received some attention was the scrapping of the World Square stop. The MR claims that the primary cause was the substantial engineering that would be required to make the stop compatible with the Disability Discrimination Act and that it would generate lower patronage than the adjacent stops at Town Hall and Chinatown. While there is some logic to this, the decision will put increased pressure on these two potentially very busy stops and their surroundings; for example, people attending the cinemas in George Street are now likely to use – and add to the congestion surrounding – the Town Hall stop. The MR concedes this but claims the increased patronage is manageable and can be catered for in part by the longer platforms required to service 67-metre vehicles.

The implications of some of the other changes mentioned in the MR did not receive the attention they deserve. The first is the change in technology for the wire-free section of the line, between the Town Hall stop and the terminus at Circular Quay. In the original approval it was envisaged that the LRVs would rely on battery technology for this section, with overhead charging conductors to be installed at the Circular Quay, Grosvenor Street, Wynyard and QVB stops.

With LRV manufacturer Alstrom’s involvement in the Connecting Sydney consortium, it should not come as a great surprise that the company’s “Aesthetic Power Supply” (APS) has been chosen instead. This involves a continuous electrical feeder “third rail” embedded in the road surface between the LRV tracks. Unlike conventional third rails, this is safe for pedestrians, comprising conducting segments placed at regular intervals separated by insulated joints. These segments are only energised when they are trigged by a radio signal as the LRV passes directly over them. Power is collected through two collector shoes under the LRV (see diagram).

Aesthetic Power Supply (APS) diagram (from Alstrom Rail Infrastructure Delivering Lifecycle Solutions)

A section of APS track showing the neutral sections at the end of the powered segments plus one of the insulating joint boxes (from Wikipedia)

It has to be noted that only a handful of light rail systems have used APS since its inception in the Bordeaux tramway which opened in 2003. It was installed in the Angers and Reims systems which opened in 2011 and the new Dubai tramway which opened in November this year (2014) – and that’s about it.

There were also some reliability problems with the original Bordeaux system but these appear to have been ironed out. What is unclear however is how APS will cope with the sort of torrential rain Sydney has already seen this summer, when streets can be flooded for short periods of time.

The other issue of possible concern is that use of any wire-free technology tends to lock the light rail system to specific rolling stock suppliers, in this case Alstrom and any manufacturers they license. In the main, conventional trams and LRV use fairly universal technologies such as standard gauge track (though this of course can be varied) and overhead wires usually energised to 750 volts DC; trams with these specifications can be purchased virtually off the shelf or even borrowed from another system, as happened in Sydney recently. Wire-free systems are much rarer and those from different manufacturers are incompatible – for example, the battery system now abandoned for the CESLR is based on completely different principles to APS.

The other changes to the CESLR are comparatively minor, comprising some stop rearrangements and track realignments, though even these can have potentially adverse consequences. For example, as Bambal Shakibaei’s Transport Sydney blog points out, the changes to the location of the Racecourse stop and the track in this section means that users will have to cross Alison Road to reach Randwick Racecourse and could also adversely impact the recently-completed Alison Road bikeway.

Another change is the methodology used to construct the tunnel required under Anzac Parade. Previously the options being considered were chosen to avoid direct impacts on the road surface, but the MR has adopted a conventional cut-and-cover construction approach. While all traffic lanes on Anzac Parade will be maintained, the road surface will have to be realigned temporarily on several occasions to accommodate the tunnel’s construction in stages.

The release of the MR is significant in that it indicates the level of detail being considered to bring the CESLR project to reality. Some major question marks remain though, such as how the interface between a not particularly tram-literate Sydney public and 67-metre LRVs will be handled in the proposed George Street mall and how reliable – and safe – the wire-free section will be in this city’s almost tropical summer climate.