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TOLLED BRIDGES REVIEW: PHASE ONE REPORT - 29 OCTOBER 2004:

5. Alternative Tolling Regimes

5.1 Assessment Methodology

Erskine, Forth and Tay Road Bridges

MVA was commissioned to model the strategic response to changes in toll levels at Erskine, Forth and Tay Road Bridges using the Transport Model for Scotland (TMfS). TMfS is a multi-modal, strategic demand and assignment model which takes account of traveller responses to change.

The results discussed in this report are derived from the model base year of 2002 and provide a good indication of how travel patterns would settle to a state of equilibrium based on changes to existing tolling regimes. Results therefore do not take account of traffic growth but do incorporate suppressed and induced journeys which significant changes to tolls may generate. All results are relative to the "status quo" scenario only i.e. they are only indicative of expected changes between the scenarios modelled.

Each of the tests run by MVA was analysed to provide a general understanding of the likely effects of changes to the toll regimes at each of the three tolled bridges. The analysis is limited to more general effects as opposed to specific junction delay or link effects at each bridge or principal alternative route. For this reason there can be some variation in the detail when comparing TMfS results with results from traffic models that have been specifically designed to evaluate local traffic conditions. Accordingly, TMfS results should be read as indicative predictions only and interpreted in this report as being relative rather than absolute values.

The MVA report analyses the operational effects to the highway network at the morning peak with respect to changes in levels of traffic flow at each bridge and their principal alternative routes, changes in annual average daily tolling revenue, changes in route and mode choices and changes in congestion and emissions.

The mode choice analyses assume no change in the highway and public transport networks and assume adequate public transport capacity to absorb any increase. This is important from a policy perspective. Further analysis of transport implications would be needed if tolling changes are proposed at Erskine, Forth or Tay.

As all of the analysis is undertaken for the base year (2002) actual magnitudes of changes in congestion levels are relatively low, particularly at Erskine where there is less congestion in the peak hours. Actual congestion values (in vehicle minutes per km) were not included in the analysis which makes it difficult to gauge the true magnitude of potential congestion problems under each test. Further analyses could be undertaken to provide a more detailed assessment if required.

The modelling work did not take account of discounts available at Erskine and Forth Bridges thus results assume all vehicles are charged at the full rate appropriate to their classification.

Skye Bridge

As Skye Bridge lies outside the boundary of the TMfS modelled area it is not possible to use TMfS to assess alternative tolling regimes on that bridge. Research was commissioned from Scott Wilson to undertake a review of traffic trends and to forecast of future traffic growth for the Skye Bridge.

5.2 Scope of alternatives assessed

The terms of reference specified an analysis of the implications of removing the tolls; reducing the tolls; maintaining the status quo; increasing the tolls; differential toll by time of day, car occupancy, and vehicle class.

For each of the four tolled bridges, the status quo was modelled to provide base results against which alternative tolling scenarios could be compared. As circumstances are very different at each bridge, different tests were run in respect of each Bridge.

Alternative tolling scenarios were modelled as follows:

General scenarios - concurrent tests:

• 'no tolls' for all four bridges. In line with the Partnership Agreement commitment to ending tolls at Skye, this was the only alternative scenario modelled for the Skye Bridge.
• 'reduced tolls' set at 50% of current tolling levels for Erskine, Forth and Tay
• 'increased tolls' equating to a 2 return-trip toll for cars on all three bridges, with a corresponding percentage increase for HGVs

Specific scenarios - independent bridge tests:

• As Forth and Tay tolls already incorporate differentials for vehicle class, modelled increases and decreases took this into account.
• A differential tolling scenario of 50p for cars and 1.00 for HGVs (both each way) was modelled for Erskine where currently all vehicles pay 60p in each direction. The differential tolls modelled for Erskine were chosen to a) test easier toll payment (one coin required rather than two) and to b) find a balance in increasing HGV tolls without diverting these vehicles to the already-congested Clyde Tunnel
• As TMfS was not sufficiently developed to model toll differentials by time of day during Phase One ^s, a high toll was modelled for Forth and Tay to obtain an indication of sensitivity to peak hour charging. The scenarios modelled (5 for cars/7 for HGVs at Forth, 4 for cars/6 for HGVs at Tay) were chosen following discussions with Bridge and Local Authority Transport officials. A larger increase was not modelled for Erskine as it does not have a congestion problem.
• As a result of discussions with bridge and local authority transport officials, the effect of one-way tolling at Erskine Bridge was tested. Two scenarios were run: one at 1.20 (northbound only) to test the effect of a change from two-way to one-way tolling keeping the cost of the return journey the same, and another at 2.00 (northbound only) to additionally test the effect of an increased toll. This latter one-way test provides a direct comparison of results with the previous test of 1.00 in each direction. As with Forth and Tay positive traffic control can be exercised by collecting tolls prior to the traffic crossing the structure and consequently northbound rather than southbound tolling was tested for Erskine.

5.3 Results

Modelling results indicate that changing tolling regimes can have significant local and strategic effects on the network as well as immediate financial implications. Key results are summarised below:

5.3.1 Interaction of Traffic between Tolled Bridges

The modelling results show a small amount of interaction between Tay and Forth Road Bridges in the northbound direction with around 8% of northbound Tay Road Bridge traffic having arrived via the Forth Road Bridge. For trips involving both these bridges, MVA anticipates that any change to tolls which would influence a shift in route choice further west for the first estuarial crossing would also be felt at the subsequent crossing. For example a route choice to Dundee involving Kincardine Bridge rather than the Forth Road Bridge is more likely to involve Friarton Bridge rather than the Tay Road Bridge, even though the Tay Road Bridge is toll-free in the northbound direction. The same effect is predicted for southbound journeys.

There is no interaction with the Tay and Forth Road Bridges from Erskine Bridge.

5.3.2 Erskine Bridge

There are three strategic crossings of the River Clyde: Erskine and Kingston Bridges and the Clyde Tunnel. The distance between the Kingston Bridge and the Erskine Bridge is 13 miles. Between these two bridges are the Clyde Tunnel which provides a strategic connection between the A8 and M8 in the south, and the A814 and A82 in the north. Other River Clyde crossings are all to the east of the Kingston Bridge. Both the Kingston Bridge and Clyde Tunnel are currently subject to significant congestion problems, particularly at peak times. Changes to Erskine Bridge traffic levels will impact on these two alternative routes and therefore on levels of congestion within Glasgow City and on the motorway network.

The majority of origins and destinations to Erskine Bridge at the morning peak are either within 30 miles of the bridgehead area or more strategic but focused on the West of Scotland.

Traffic flows on the Erskine Bridge are more sensitive to small changes in tolls than traffic on the Forth and Tay Road Bridges. MVA attributes this to the much closer alternative route choices, mainly the Clyde Tunnel and also the Great Western Road/Clydeside Express as an alternative route for traffic originating in the northwest and bound for Central Glasgow (or beyond in North or South Lanarkshire).

Removing or decreasing the toll at Erskine Bridge has the potential to attract traffic from these (and other) alternative routes. As the least congested of the three tolled bridges analysed by TMfS, Erskine Bridge has capacity to cope with increases in traffic to a better degree than either Forth or Tay Road Bridges, which are already congested at peak times. Increasing the toll has the opposite effect and results indicate traffic diverting to alternative routes.

Modelling of tolling in the northbound direction only resulted in an increase of traffic in the toll-free southbound direction and a reduction in northbound traffic. These changes were significant even where the toll for a return trip across the Bridge did not increase from the current 1.20. The changes were even more marked when the northbound-only toll was set at 2.00.

A slight increase in Erskine traffic resulted from the differential toll by vehicle type although, as expected, this masks a slight decrease in HGV traffic.

Mode choice effects apparent in all the Erskine Bridge tests were minor.

5.3.3 Forth Road Bridge

The morning peak analysis indicates that 70% of traffic travelling north across the Forth Road Bridge has an origin in Edinburgh and almost half of these trips has a destination in Fife. In the southbound direction, which is the dominating commuter corridor into Edinburgh from the north in the morning peak, 60% of traffic has a destination in Edinburgh, although only 12% has a destination in central Edinburgh.

Removing or decreasing tolls at the Forth Road Bridge has the potential to attract additional traffic, principally from Kincardine Bridge. As the Forth Road Bridge is already heavily congested in the morning and evening peaks, additional traffic would further increase journey times and extend the duration of the peak periods.

Increases in tolls resulted in traffic diverting to Kincardine Bridge. Kincardine Bridge and its junction with Kincardine village already experiences severe congestion in the peak periods. A new Upper Forth crossing, together with improvements to the approach trunk roads and the existing Kincardine Bridge, ^t have been included in the Executive's investment programme. A public local inquiry (PLI) will be held during November and December 2004 and a decision is expected by spring 2005. If the PLI approves the proposal, construction of a new bridge could commence in 2005/06 with completion expected by 2008/09. The project will involve a new bridge and refurbishment of the existing bridge at a combined estimated cost of 100m.

Results of the largest increase (to 5 for cars and 7 for vehicles) suggest that traffic flows may be sensitive to higher tolls employed for demand management purposes. However the effects of this type of tolling regime on travelling choices such as mode, route and time of journey have not been tested. It is hoped that TMfS will be sufficiently developed to undertake such analysis during Phase Two of the review, if required.

When tolls are removed or reduced there is only a minor change in public transport patronage. The modal shift is more marked when tolls are increased although MVA suggest that further increases may be expected if additional public transport infrastructure or improvements were put in place.

5.3.4 Tay Road Bridge

The morning peak analysis indicates that around 80% of northbound Tay Road Bridge traffic has an origin in Fife, two-thirds of which have a destination in Dundee. In the southbound direction, 87% of traffic has a destination in Fife, half of which originates in Dundee.

Removing or decreasing tolls at the Tay Road Bridge has the potential to attract additional traffic, principally from Friarton Bridge. As the northern exit of the Tay Road Bridge leads traffic directly into Dundee City centre, Dundee already experiences short spells of congestion at morning and evening peaks. Additional traffic re-routed from Friarton at these times would add to this problem.

Increases in tolls resulted in traffic diverting to Friarton Bridge.

As with the Forth Road Bridge, results of the largest increase (to 4 for cars and 6 for heavy goods vehicles) suggest that traffic flows will be sensitive to higher tolls employed for demand management purposes. It is re-emphasised that the wider effects of this type of tolling regime have not been tested.

When tolls are removed or reduced there is only a minor change in public transport patronage. The modal shift is more marked when tolls are increased although MVA suggests that further increases may be expected if additional public transport infrastructure or improvements were put in place. This suggestion was supported by some consultees.

Interest was also expressed in modelling of northbound tolling. The Tay Road Bridge Joint Board are presently considering options for relocating the tolling stations to the south end of the bridge to facilitate northbound tolling and ease congestion and pollution in Dundee City centre.

6.3.5 Skye Bridge

As the Skye Bridge lies outside the TMfS modelled area, it was not possible to model traveller responses to removing the tolls using this model. However as Skye Bridge operates well below capacity it can clearly accommodate significant increases in traffic without affecting the free flow of traffic.

The Scott Wilson forecast of future traffic growth at Skye considers the likely effects of removing the tolls. At the basic level, removal of the tolls will increase the attractiveness of the Skye Bridge route as a means of travelling between Skye and the mainland. However the extent to which this will generate additional vehicle trips is largely dictated by the potential for trip reassignment from alternative routes, namely the Mallaig-Armadale ferry, the potential for new trips following the release of any suppressed demand due to the reduction in travel costs and the opportunity for trips to switch to different vehicle classes. The Executive has no plans to withdraw the Mallaig-Armadale ferry service as a consequence of its commitment to end the discredited toll regime on the Skye Bridge.

Around 43,000 vehicles used the Mallaig-Armadale ferry in 2003, with 95% of trips taking place between April and October. Scott Wilson conclude that it is likely that current travellers whose route choice is dictated by travel costs already use the bridge, and those travellers who wish to experience the ferry route (mainly tourists) will continue to do so. The numbers of vehicles likely to divert from the ferry to the bridge are unlikely to have any significant impact on the free flow of traffic on the bridge.

5.4 High Occupancy Vehicles

5.4.1 FETA's Draft Local Transport Strategy

The executive summary of FETA's draft LTS includes objectives which highlight FETA's commitment to increasing vehicle occupancy - "To optimise the potential number of public transport person trips across the Forth" and "To increase car occupancy across the Forth Road Bridge".

5.4.2 SESTRANS Single Occupancy Vehicle (SOV) Reduction Target

The SESTRANS Regional Transport Strategy 2003 sets a target of achieving, by 2022, a reduction in the percentage of people commuting to and from Edinburgh by SOV, by 10% from each authority to a 2001 base, e.g. Fife to reduce from 76% in 2001 to 68% by 2022. `

5.4.3 High Occupancy Vehicle Lanes / Single Occupancy Vehicle Tolling

Forth faces serious congestion during the morning and afternoon peak periods and FETA has asked consultants to consider the possibility of HOV lanes or SOV tolling. The possibility of using high-occupancy vehicle (HOV) lanes or charging a higher toll for single occupancy vehicles (SOVs) is potentially attractive because of the opportunities it may offer to reduce the volume of single occupancy vehicles crossing a bridge during the peak period - which can exceed 70%.

Other tolled bridges in Central Scotland do not face the same volumes of traffic nor suffer comparable levels of congestion. There is little congestion on the Erskine Bridge and limited peak hour congestion on the Tay Bridge so that the benefits of HOV lanes or SOV tolling may be less significant from a traffic management perspective, but remain desirable in terms of promoting sustainable transport.

Technical consultants have examined options for reducing the number of SOVs on the Forth. The advice from these studies has been consistent in suggesting that HOV lanes present a range of operational issues (see details in the section on HOV lanes below) which are difficult to resolve given the physical and technical constraints of the Forth Road Bridge structure. Currently attention is likely to focus on schemes levying higher tolls or charges for SOVs.

5.4.4 Single Occupancy Vehicle Tolling

Setting a higher charge for SOVs should encourage an increase in travel by HOV vehicles, such as car sharing and buses, which should help in reducing the number of vehicles crossing the bridge during peak periods.

FETA plans to replace the existing manual toll booths with a new 'state of the art' automatic electronic plaza based on vehicles using electronic tags. The key benefit of electronic 'tag' tolling through the new automatic toll booths will be that vehicles with tags do not need to stop at the toll booths. This will allow for free flowing traffic and a reduction in queuing.

At present fully automatic electronic tolling is not capable of distinguishing between HOVs and SOVs so it would be necessary to operate a manual tolling approach in identifying HOVs and SOVs.

It is recognised, however, that the uptake of electronic tolling will take some time to build up and that FETA will need to continue providing manual tolling during this period and beyond for drivers who insist on cash payment. Experience on newer crossings with electronic tolling, such as the Dartford bridge, suggests that a large proportion of drivers still prefer to use cash payments despite the option of electronic tolling which avoids the need to stop at the toll booth.

This provides an opportunity to explore the implementation of manual tolling of SOVs alongside electronic tolling of other vehicles in the short to medium term. Research and development of experimental systems is being undertaken to try to develop a reliable automatic system for identifying vehicle occupancy. Should these developmental technologies reach a stage where they are viable the design specifications of the new toll plaza and its supporting systems will be capable of allowing it to be upgraded to accommodate the new technology.

One of the factors which needs to be weighed in the balance is whether manual based SOV tolling would be detrimental to the free-flowing benefits of electronic tolling. This is a significant consideration as SOVs currently make up more than 70% of the vehicles crossing the bridge during peak periods.

5.4.5 Dedicated HOV Lanes Issues

FETA has considered the possibility of a dedicated HOV lane for passenger vehicles (buses and minibuses) in addition to private cars with two or more occupants. This approach would involve physically separating the two lanes over the bridge and to direct HOVs through HOV toll booths to access the dedicated HOV lane.

The Forth Road Bridge is limited to two lanes in each direction with no hard shoulder. Consistent advice from technical consultants employed by FETA has identified problems with this approach.

Estimates suggest that more than 70% of traffic on the Forth is made up of SOVs and it will take some time to reduce this level. Currently each all-purpose lane handles 50% of the traffic (HOVs and SOVs) and the bridge is already at its capacity limit during peak periods.

The diversion of SOV traffic from the dedicated and more lightly trafficked HOV lane to the non-HOV lane would, inevitably, increase the level of traffic on the non-HOV lane well above its current 50% volume of traffic which would then create greater delay, queuing and congestion for traffic using that lane. Estimates suggest that even with a 50% increase in HOVs using the dedicated lane the diversion of remaining SOV traffic onto the all-purpose lane would generate queues of more than 7km.

5.4.6 Construction of new dedicated HOV lanes

On a land based roadway, construction of an additional HOV lane might be a cost-effective option, but this would be too costly and difficult technically on the Bridge. Consideration was given to running vehicles on the side access routes and via the central reservation, but this proved to be neither a technically viable (the bridge structure could not support the additional loading) nor a cost effective solution and was rejected ^u.

5.4.7 Traffic Management

On a bridge with only two lanes, separation of a dedicated HOV lane from an all-purpose lane would involve managing potentially hazardous weaving of traffic between lanes (to access the correct lanes for crossing and leaving the bridge). Handling accidents and breakdowns without disrupting the free flow of traffic would be difficult. Ensuring an adequate level of lane discipline would be essential to the provision of dedicated HOV lanes. The operation of Police motorbike patrols was previously considered, but because the bridge has no hard shoulder to pull over offenders it was considered to be impractical. Other approaches to ensure appropriate lane discipline would need to be considered to support dedicated HOV lanes.

These constraints work against HOV lanes being an optimum solution for the immediate future, but the alternative of applying higher differential tolls or charges on SOVs does offer a possible way forward in achieving FETA's objective of increasing car occupancy across the Forth Road Bridge.

5.4.8 SOV Reduction Measures - Further Work

FETA are also examining proposals to encourage local employers to negotiate car sharing schemes which could be policed by employers and which would attract discounted rates for crossing the bridge.

Consideration should be given to engaging consultancy time, within the Executive's consultancy framework arrangements, as part of Phase Two of the Bridges Review. The purpose of this consultancy project would be to provide Ministers with the benefit of objective technical advice on the most cost-effective options for achieving FETA's objective of increasing car occupancy across the Forth Road Bridge.

5.5 Alternative Tolling Regimes -Key Points

Modelling results should be read as indicative predictions only and interpreted in this report as being relative rather than absolute values.

• Currently operating below capacity, Erskine Bridge has the potential to offer some measure of relief to high levels of congestion in Glasgow. Removing tolls completely had the biggest impact on this. One-way tolling, keeping the cost of a return journey at current toll prices (i.e. 1.20 for a one-way trip instead of 60p each way), produced a significant increase in southbound (toll-free) traffic but caused traffic to divert to Glasgow to avoid tolling in the northbound direction. Total traffic levels increased slightly when the vehicle differential scenario was tested although there were indications of some heavy vehicles diverting to Glasgow.
• The traffic characteristics and future growth discussed in section 4 strongly indicate that the current tolling regime does not provide FETA with adequate means of managing its peak demand while significant general tolling increases had negative impacts on existing congestion at Kincardine and the Forth Road Bridge itself respectively. Differential tolling by time of day may offer FETA the opportunity to address congestion without adverse effects for Kincardine and it is recommended that this be further explored during Phase Two of this review.
• The situation at the Tay Road Bridge is similar to that at Forth although to a lesser extent. There is a clear need to manage peak hour traffic to improve congestion and air quality and the likely impact of relocated tolling stations should be evaluated during Phase Two of this review to establish whether further demand management measures are desirable.
• Skye Bridge can accommodate significant increases in traffic without affecting the free flow of traffic.
• FETA is committed to promoting increased use of high occupancy vehicles. Although FETA's consultants have given serious consideration to the possibility of HOV lanes and SOV tolling, they concluded that FETA's overall objectives are best served by getting all vehicles over the bridge during the morning peak as quickly as possible. Nevertheless, options leading to the introduction of some form of higher SOV tolls will be actively considered. It is likely that these will be based on manual tolling in the short to medium term, with the possibility of migrating to automatic or electronic vehicle occupancy tolling if and when reliable systems become available in future.

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