Transmission Gully reality check

Summary:

Expensive to build, hard to finance

Requires a two thirds subsidy from ratepayers or petrol tax.

Marginal benefits

Vulnerable to earthquakes

Crosses a faultline at point of greatest earthworks. Unlikely to be cleared before coastal route in event of an earthquake.

Worsens other problems

Serious environmental effects

Public support exaggerated

Recommendations

Adopt a sequenced approach that does not rule out the road but follows the following steps:

1. Require genuine assessment of alternatives, including alternatives to roading by independent assessors.

2. Invest in upgrading passenger transport alternative, including better local services.

3. Consider a peak time charge on the existing road to reduce effects on communities and assess true demand for Transmission Gully.

4. Adopt electronic pricing for trucks to encourage a shift in freight from road to rail.

5. Reduce the speed of traffic and undertake safety improvements on dangerous high speed sections of the coastal route, through a combination of enforcement and engineering.

If demand for Transmission Gully persists after these measures:

6. Allow the motorway to be built,

(i) financed largely by tolls with the percentage subsidy from rates or petrol tax no greater than that available to public transport and;

(ii) only in combination with:

 

 

Discussion:

Expensive to build, hard to finance

Due to fairly rugged terrain and motorway standard design specifications, Transmission Gully would be a very expensive road to build - estimated at $245 million (including $21 million for an electronic tolling system). It would also be prone to cost overruns as there has not been a road building project of this scale in recent history.

To meet normal road funding criteria even under the current cost-benefit methodology, the benefits of Transmission Gully would have to be several times what they currently are. This should serve as a strong warning against construction.

Transmission Gully would not reduce the length of the trip from the Kapiti Coast to Wellington. The distance traveled would be the same as the current state highway. It does not have the natural advantages of other major toll routes of the past such as the Auckland Harbour Bridge or the Christchurch-Lyttelton tunnel, where traffic otherwise has to travel significantly further.

Because the two routes are the same length, people will only be prepared to pay significant tolls if the coastal alternative is still congested, or if there is a toll on both roads. Consequently, toll levels currently under discussion ($1-2 per trip) are far lower than the true cost in the order of $12 per peak time trip. Tolls at the low, optimum revenue gathering level are expected to pay for only $60-80 million of the full $245 million cost.

Therefore the road cannot be built without being highly subsidised by rates and/or a regional petrol tax. The tolling figures being discussed suggest a subsidy in the order of 70%. Sourcing income from a regional petrol tax would see the average motorist further subsidising trucks and other diesel vehicles, as well as subsidising those who use Transmission Gully most. This would see even more motorists switching to diesel and defeat the purpose of the petrol tax. Sourcing income from rates would see homeowners further subsidising road users.

 

Marginal benefits

On the state highway north of Wellington there are four main congestion points:

1. The Mana roundabout.

2. Mackay's crossing.

3. Traffic lights and intersections in Paraparaumu.

4. Traffic lights and intersections in Waikanae.

Transmission Gully will eliminate only one of these problems - the Mana roundabout. Mackay's crossing is set to be addressed by an overbridge, irrespective of whether Transmission Gully goes ahead. Problems at Paraparaumu and Waikanae will only be exacerbated.

The predicted savings in travel time are marginal in many instances, compared to realistic improvements to the current coastal route, costing $33.2 million. Comparing Transmission Gully to an improved coastal route, Transit figures show no weekday scenario with a time saving greater than 1 0 minutes. There would be no significant time savings during off-peak periods. Transit New Zealand believe that improvements to the coastal route can deliver 40% of the benefits of Transmission Gully for 11 % of the cost.

Transmission Gully would be much steeper than the coastal route, with a highest point 180 metres further above sea level. South bound traffic would face a very steep climb to the Wainui saddle, with an equivalent grade to the Ngauranga Gorge but 2-3 times as long. This would make the route highly unattractive to trucks, and trucking representatives have already indicated they won't use it. Non-use by trucks would defeat one of the main purposes of the road for those people living next to the current route: relief from truck noise, fumes and vibration.

The safety benefits of Transmission Gully are highly questionable. On the coastal route the less congested, high speed sections have the worst safety records, and might well be made worse if congestion relief from Transmission Gully led to higher speeds. The long steep descent at the north end of the Gully route has a high potential for serious accidents. Road safety would be better served by reducing the speed of traffic on the dangerous sections of the coastal route through a combination of enforcement and engineering.

Vulnerable to earthquakes

One of the primary arguments used to promote Transmission Gully is that it will provide an alternative route out of Wellington in the event of a major earthquake. In such an event the probability is that both roads would in fact be closed. Because Transmission Gully would cross the fault line at the area where the greatest earthworks are required, it would be more difficult to clear and re-open than the coastal route. Slips would have to be cleared by working from the ends and trucking material away. In contrast, the existing highway could be cleared much more quickly, by working at many points simultaneously and simply pushing the material into the sea.

Other arguments used by proponents are largely spurious, such as the claim that the road will be good for the economy. The road will in fact be a drain on the region's resources.

Worsens other problems

Transmission Gully will have significant impacts on the development of the region, most significantly a burst of commuter suburb development on the Kapiti Coast, exacerbating pressures on the area's coastal landscapes, limited water supply, sewage disposal system and ecological areas. If this growth is allowed to continue unabated, the resulting traffic growth will swamp the time travel gains of Transmission Gully.

Transmission Gully will greatly exacerbate traffic growth and congestion where it rejoins the current route. To the north, the problems at Paraparaumu and Waikanae will be significantly worsened by increased expectations. To the south, there will be increased traffic pressure on the motorway from Linden to Wellington and on the road network within Wellington City.

The initial relief of traffic congestion would encourage passengers on public transport to switch to car use. The reduced demand for public transport would tend to lead to higher fares and reduced services, encouraging further switching to car use until the road was just as slow as public transport. In contrast, improving public transport would attract drivers and so reduce the congestion, thus improving conditions on both road and rail.

By undermining the provision of public transport, Transmission Gully would further reduce mobility for people without cars, notably the young and the old.

Serious environmental effects

Substantial adverse environmental effects of Transmission Gully include:

Public support exaggerated

The public support Transmission Gully, as long as they don't have to pay for it. Even the McDermott Miller willingness to pay survey, which may have exaggerated support, found that only half of the community is prepared to pay the full cost of the motorway through tolls, increased rates and an increased petrol tax. If the supposed benefits are reflected in the distribution of rates increases, support from Porirua and Kapiti drops as low as 28% and 39% respectively.

In the willingness to pay surveys the public were not given the option of an improved public transport system as a cheaper alternative to Transmission Gully. The rail service is in a dire situation, with an infrequent service and stations in a state of disrepair.

Improvements to the rail service, including an extension to Waikanae, are already planned for the next five years. The Regional Land Transport Strategy identifies a number of additional projects needed to bring the service up to standard, but applications for funding have been refused by Transfund.

Recommendations

Adopt a sequenced approach that does not rule out the road but follows the following steps:

1 . Indicate to Wellington local authorities and relevant transport agencies that you would not support early construction of Transmission Gully without a genuine assessment of alternative option packages. This assessment should canvas combinations such as improving public transport, managing suburban development on the Kapiti Coast, and road pricing. Relative assessment of Transmission Gully should consider the costs in terms of induced traffic and greater suburban sprawl.

2. Direct Transfund to provide for investment in passenger rail services as an alternative means of transport.

3. Consider peak time road pricing of the coastal route to reflect the costs of road use, reduce effects on the local community and evaluate the true demand for road use in the corridor, particularly Transmission Gully.

4. Adopt electronic pricing for trucks to encourage a shift in freight from road to rail, and from the coastal route to Transmission Gully if it is constructed.

5. Ask the Minister of Police to ensure that adequate steps are taken to reduce the speed of traffic on dangerous high speed sections of the coastal route. Ask Transit NZ to consider introducing lower speed limits, if justified by cost benefit analysis.

If demand for Transmission Gully persists after these measures:

6. Allow the motorway to be built,

(i) financed largely by tolls with the percentage subsidy from rates or petrol tax no greater than that available to public transport and;

(ii) only in combination with:

You should note that in the meantime Transit New Zealand will be proceeding with improvements to the coastal route, assuming that resource consents are obtained and there is no political intervention. Construction of some of these improvements is already underway.