Most Useful Network items are about simplifying infrequent local bus routes to build an economical network of more direct buses operating every 20 (or occasionally 10) minutes. Such revamps are necessary for vast swathes of Melbourne suburbia that now see only indirect and infrequent buses.

However we also need buses to take on more of a rapid transit function. We've done it a bit for corridors that stand in for sometimes proposed railways like City to Doncaster or Huntingdale to Rowville. However these are both radial corridors. More than these are needed for a full connected network.

Many plans (eg Melbourne @ 5 million) have advocated growth in suburban centres or, more nebulously, clusters to decentralise jobs and activity. These need rapid access from multiple directions to reach their full potential. Frequently stopping buses stuck in traffic excite few people, even if they run every 15 minutes like a SmartBus. One concept that can work is a frequent express service between a large destination and a major interchange, such as the Route 401 example below. Perhaps the most significant thing about this one is it's a circumferential link. Hence it complements, and even relieves stress on, the existing radial network. That's important where this is already running close to capacity.    

Transport demand

I will not go into travel demand modelling in any detail (though you can here or, if you want a quicker read, then here). There's other factors, but very roughly if centres are big and close to one another there are likely to be many trips between them. Make them further apart and the centres are more self-contained, meaning fewer trips. There are also fewer trips where centres are smaller. It's a bit like gravity, hence the name of the theory. A rough diagram is below.  

When there's many trips you will need capacity. More than one two lane road (even with buses) will be needed. Congestion will build up. There will be a need for real mass transit, including dedicated high capacity modes like rail on their own rights of way. These create a speed and convenience edge over driving and thus higher modal share for public transport (indicated by the green parts of the link lines above).  

Another approximation is below. Larger centres not only attract more trips but attract more on public transport as this is the most efficient mode for trips to large centres. The CBD is the stand-out as you can see on the top right.

Some cities do better than others. Eg Sydney has a less radial rail network and busways between some of its major outer suburban centres. Its non-CBD centres (eg Chatswood, Parramatta) get higher public transport modal share than do equivalents in Melbourne. But even within Melbourne's there can be a lot of variability. University precincts like Monash Clayton and shopping centres like Chadstone can do relatively well despite lack of rail.

Other non-rail centres, and especially industrial and airport precincts do very poorly,  not least due to poor service levels. Smaller shopping centres can be more car-oriented than larger centres. Though not in all cases. A medium-sized centre such as St Albans, in a low income area, has very high numbers of shoppers who arrive by bus.

In many areas local councillors and retailers underestimate the number who reach their shops on foot, bike or even bus as they push for more parking. Cars, due to their movement and storage requirements requiring use of scarce land, are spacially inefficient. At high speeds and in large volumes they are also a nuisance for users of all other transport modes, including walking, cycling and buses.

Centres that aspire to be some place better cannot afford to have their retail turnover and job numbers artificially constrained by car parking and movement (which crowd out efficient transport modes and denser development). A centre that wishes to grow needs public transport to provide an increasing proportion of new trips that its growth generates. For this to happen public transport accessibility from  multiple surrounding areas needs to be good.

Access and connectivity mapping

A good way to assess this is by looking at SNAMUTS connectivity maps which have been prepared for various cities including Melbourne. I'll leave it to you to read the fine print on what each map means. In layperson's terms you can use these maps to check things like an area's connectivity to other destinations, population catchments and overall accessibility.

It's important to be aware that there are minimum service standards very similar to the 20 minute criteria I've used for the 'Useful Network'. This accounts for the large dollops of 'Urbanised areas without minimum service' on the SNAMUTS map below (black).  

The impact of existing Useful Network routes including orbital SmartBuses is clear on the map. However they are mostly red or orange. They are too slow to give their catchments yellow (ie above average) accessibility like you see on rail corridors out to Box Hill, Oakleigh and around Sunshine.  

To improve accessibility you basically need fast and frequent connections. In mass transit speed is constrained by the number of times it has to stop and, critically, if there is impediment from cross-traffic (which can include walkers and other public transport services). Frequency is proportional to the number of buses you can put on and inversely proportional to travel time. So if you have fast travel times (especially if there is low variability) you can achieve high frequencies.

People throughput is a function of frequency and vehicle capacity, so if you have large vehicles like articulated trams or buses then you can carry huge numbers of people per hour provided that they face few impediments. Fare revenue per bus operating hour is also higher.

Route 401 between North Melbourne and Melbourne University, for example, has 66 passenger boardings per bus operating hour, about three times the average for Melbourne buses. 301 between Reservoir and La Trobe achieves 74, while 601 between Huntingdale and Monash University attracts over 200 boardings per bus service hour. These are all buses operating on roads with traffic lights.  

The ideal would be something that approaches this definition of a wormhole.

In practice we don't need instant. We just need short. The maximum speeds of our trains, trams and buses are already plenty high enough. What's important is that they are kept moving at a good speed for most of the time. Even our suburban trains rarely exceed 35 km/h average despite their maximum being three or so times times this. Buses average around 22km/h while trams, due to mostly running in mixed traffic, are in the teens. Add waiting and connection times and overall end-to-end speeds may be halved.  

If we added some fast and frequent connections we could fill that SNAMUTS accessibility chart with lots more green and lots less black. More precisely, 20 minute-style Useful Network routes would turn black to red in the outer areas. Closer in some short, fast and very frequent links would turn orange areas to yellow and yellow areas to green with vastly improved accessibility. There could be particular gains at centres we wish to build up including around Sunshine, Box Hill and the Chadstone-Monash precinct.

The gradual approach (which should be done on a larger scale) are initiatives like more bus lanes, more priority at lights, articulated buses with dual leaf doors, and higher frequency, potentially including headway managed turn-up-and-go timetables. Sometimes unforeseen events can lead to unexpected progress, for example we now have all-door boarding due to COVID-19 social distancing.

All this could be considered a poor man's BRT as part of a SmartBus 2.0 refresh. Their cost-effectiveness would be exceptional and they would spread benefits to large areas. However on their own they may not be seen as the sort of high-profile step change that something like a new rail link might involve.

The 'bus wormhole' concept

An advance on the gradual approach could be the 'bus wormhole' concept. This is both infrastructure and service heavy. Buses would be fully separated from traffic, operating on their own way (which could be elevated or underground in parts where land is unavailable).

Costs per kilometre would be very high. Consequently 'bus wormholes' would be short sections on the busiest corridors in the most intensive suburban clusters, preferably intersecting or feeding trains at least every 10 minutes. Favoured locations might include major off-rail locations such as universities and shopping centres (some mapped here) that are much less accessible according to SNAMUTS than a railway station a few kilometres away.

Wormholes may have either dedicated routes (such as short shuttles like the 401) or be used to speed up the busy ends or middles of longer through routes (including some SmartBuses). You might only have five or ten in all of Melbourne as each might cost in the hundreds of millions to low billions depending on length and complexity.

You can imagine their role as per the diagram below - bringing key nodes together to greatly increase connectivity over a wide area. Before and after SNAMUTS maps to show each wormhole's impact could be used to evaluate the merit of various proposals.    

10 bus wormhole concepts

Where might you consider bus wormholes? Location could be affected by the extent to which one would speed service relative to much cheaper BRT-light priority treatments, how it would fit in with other transport projects (eg Suburban Rail Loop) and expected patronage per kilometre of wormhole. Then of course there is cost and feasability, including whether there is room to operate a bus way at-grade (cheapest), elevated (dearer) or underground (dearest).

In all cases the interface with trains must be of a standard better than we've had in Melbourne, for instance via escalators, ramps or lifts directly onto station platforms. The gold standard is what you see below from Adelaide where changing involves just a few steps.

Potential wormhole locations include a mix of inner, middle and outer suburbs. Some might only be 2km long, with future extensions further speeding travel. I have deliberately not shown the exact route alignment or specified whether they are at-grade, elevated or underground. Below are concepts worthy of discussion (and, yes, there are some wild departures from the normally cheap and sober proposals normally considered here).  

1a. Footscray - VU - Highpoint (orange line). This wormhole connects three major closely spaced destinations. Footscray is the west's biggest rail hub that already enjoys 12 trains per hour to the CBD. It's set to get even more important with the Metro Tunnel. VU and especially Highpoint are major destinations remote from rapid transit. Services using it would likely be a merged 223/406 bus with services extending beyond the wormhole to Avondale Heights (Milleara Shopping Centre) and potentially beyond. A key consideration would be considering its value for money versus an upgrade or even rerouting of the almost parallel 82 tram, which in its current form is infrequent and does not run past the door of VUT or Highpoint.

1b. Highpoint - Essendon (red line). This would provides a much stronger link between the inner north and Highpoint by providing fast access from Essendon. It would be introduced in conjunction with a rerouting of the red orbital SmartBus between Essendon and Sunshine via Highpoint instead of Avondale Heights. As compensation the above orange route (Route 406) could be extended from Avondale Heights to Sunshine to replace the 903. Both routes would need to be much more frequent than their current 15 to 20 minutes to justify the infrastructure cost of the wormholes. A cheap service-only variation of this scheme was described here.    

2. Northern Hospital - Epping. This is a short wormhole so would be cheaper than most others here. However it connects major destinations slightly beyond the station's pedshed with a rapid transit service. The wormhole would serve multiple routes including the 901 orbital and new bus rapid transit using the Wollert Transport Corridor reservation. From there routes could fan out to directly serve multiple residential areas, similar to Doncaster's DART network, with one continuing to Craigieburn despite some potentially restricted catchment near the Hume Fwy. Although the wormhole would finish near Epping Station routes could continue east along Childs Rd as a SmartBus type corridor to at least Plenty Rd/Bundoora RMIT to allow a connection with the 86 tram to La Trobe University.  Also, an extension of one route to Greensborough, potentially via the Metropolitan Ring Road, could be a consideration if sufficient demand exists for a fast east-west route.  This could provide a faster connection than the current indirect and underused north-east portion of the 901 SmartBus or the confusing Route 566. An upgrade of Mernda line trains from every 20 to every 10 minutes off-peak would be required to get full potential from this wormhole.  

3 Preston - Heidelberg. Suggested as it is an east-west strip with a large number of major destinations and intersecting lines. A wormhole might only include the most congested sections. It's basically a gold plated version of the cheap 904 Megabus proposal described here.  Potential exists for a western extension to Coburg and a more direct connection to Essendon, linking with a previous concept for Highpoint. This would weave the currently heavily radial system in Melbourne's north into a true network with fast travel in all directions.

4. Reservoir - La Trobe University - Macleod. Basically an advance on the existing very successful 301 shuttle bus from Reservoir. The worth of this wormhole depends on the travel time saving relative to (a) now or (b) lower cost bus priority upgrades. Boosting Reservoir and Macleod off-peak train service for every 20 to every 10 minutes would produce travel time gains without the infrastructure spend so you'd do these (and smaller bus speed improvements) first before considering this wormhole.    

5. North Melbourne - Melbourne University - Clifton Hill. This is an advance on the existing very successful 401. The Clifton Hill extension should save travel time for this currently slow cross-city connection. Melbourne Metro's Parkville