Can We Trust Transport Modelling?

Are you intending to comment on East Sussex County Council’s Local Transport Plan 4 ( LTP4). For those who want to review the proposals the future projections for transport look good. Predicted to have fewer car trips whilst buses, pedestrians and cycling numbers are all up. That is  good news! …. but as a reminder LTP3 had similar aspirations

Perhaps now is the time to ask why planners are generating such positive scenarios, that you may feel are not achievable. The predictions are derived from complex algorithms. Often the process is described as a ‘black box’. The definition of which is ‘a complex system  whose internal workings are hidden or not readily understood’ . That makes anything it produces as hard to verify

Let us examine the accuracy of such models. From a lay person’s perspective the optimistic scenarios, over the last 10 years, never seem to have been delivered.

This table below , with 19% fewer cars trips, is from the LTP4. Some scenarios deliver an even larger drop in car trips. [As background, on a number of the workshops it had been asked, if some explanation could be be provided as to how the ‘black box’ generated these outputs]

In sharp contrast, in LTP4 it does admit that, across the county, the number of residents cycling has reduced by around 33% in 5 years. Plus there was a large decrease in bus provision over 20 years and even with an increase in funding, bus passengers are only 90% of pre-Covid numbers.

The largely ‘positive’ models are endemic throughout the planning process. Over the last 10 years many focus on a 10% ‘modal shift’, away from cars, towards buses and cycling. However these predictions then feed into other local plans and permeate through the whole planning process.

As an example ESCC’s ‘Hailsham, Polegate to Eastbourne corridor ‘, from 10 years ago, predicted a 10% reduction in modal share for cars. This scenario is then used by developers, on that key route, to show the extra traffic, from their developments, will be offset by the modal shift this original report had predicted. The example used here is taken from the Transport Assessment for Hindsland in Willingdon. (see Tables 6.2 and 6.3)

Method of Travel – Currently (left) and with planned improvements (right)

Notice that the developers take current traffic data and then adjust to the new modal share. So that cars, including passengers, are down from 80% to 70% and this would suggest traffic levels will be lower. To compensate, for the lower private transport, there is an increase in bus trips from 4% to 9%. That is a 125% increase, alongside  an increase for cycling up 150%. But there has never been a demonstrable increase in either.

This general approach, to overstating modal shift, is also seen in Eastbourne, by developers, on schemes such as the Magistrates Court and TJ Hughes. The positive transport assessments, produced around higher levels of active travel, seem to satisfy both developers and councils. They do not alter the reality.

Now look at Black Robin Farm (SDNP/23/04238/FUL). Aecom ,in their transport review for Eastbourne Borough Council, provided a comprehensive analysis of transport options. Their algorithm produced –

The reality check is that for Eastbourne 5% of trips are by bus  and on the Downs nearer 10%. However there is no explanation as to how 50% Public Transport could ever be achieved. Plus in this scenario cycling at 4% would be an increase from an original estimate of 1,000 to 4,000 trips p.a. Cynics might think the data was to convince South Downs National Park that there would not be a high demand for car parking. Based on the  100,000 visitors predicted p.a.

Many of these models have shown to exaggerate the modal shift away from private cars. To provide reassurance, models need to be validated, to see how accurate they were. The Government’s Transport Analysis Guidance (TAG)  “provides an overview of good practice in planning the evaluation of transport interventions to ensure robust evidence can be collected about the difference that they are making in practice. It is intended to support evaluation planning and stronger business cases for a range of transport interventions in terms of mode, type of intervention” Model guidance from Govt

In summary we are asked to take on trust the ‘black box’ approach, that transport planners are using, when our lived experience would suggest something different. Perhaps now is the time to reassess the accuracy of the predictions. If you have doubts then make this clear in your comments for LTP4 and question them about their methodology

Paul Humphreys EEAN Transport Group

Should Strategies be Realistic?

How should local government present their plans for a greener future? Is it better for them to be realistic or else have a vision that, with only limited interventions, will not be achieved? Let’s look at transport but the same is applicable for other carbon strategies.

The various local government organisations, adopt different approaches, as to the strategies they produce. Transport for South East in their modelling, do not hide away from scenarios where active travel (buses, pedestrians and cycling) actually declines. Below is a projection for 2050 called ‘Our Route to Growth’. [Note the cycle logo includes pedestrians.] Following their recent consultation, TfSE agreed to slightly modify their Investment Plan. However the point is, their models are indicative of what may happen, and not necessarily what campaigners might like.

The more problematic approach is when local government, include in their plans, what you would like, but there is no past or future evidence that these will happen. As an example, there are repeated references to the reduction of cars in local borough and county plans. This is against the backdrop of East Sussex County Council predicting, in their A22 A2290 review,  an increase in traffic of 15% from now to  2039.

So in the new draft Eastbourne Local Plan, it refers to a 15% reduction in car journeys. This is extremely optimistic. As is elsewhere, a 10% modal shift from 70% trips by car to 60%. This is in the ‘Hailsham Polegate Eastbourne corridor’ and would be offset by a 150% increase in cycling, 125% in bus trips and 60% more walking. Even those who have little experience in transport, will realise, what a colossal task this would be. As background, there has never been a decrease locally in car trips. Plus cycling and bus trips have reduced over the last twenty years.

So what can be done to prevent unrealistic predictions. TfSE have a clear requirement to monitor and evaluate any targets. This could be used elsewhere, to hold any predictions to account, such as large reductions in car journeys.

In summary, campaigners should request that ‘over ambitious claims’, although they may initially be welcome, should have a realistic delivery plan behind them

Paul Humphreys EEAN – Transport Group, Bespoke, Cycle East Sussex

Planning – Your chance to comment on transport across the region

Transport for the South East (TfSE) has gone out to public consultation on their draft Strategic Investment Plan. It closes on 12 September 2022.

This is your opportunity to comment on the long term transport plans for the South East. A plan that has a ‘golden thread’ from the Government to East Sussex and which they hope will deliver decarbonisation, multi-modal solutions and a world class transport network. It is partly designed around increased growth and supporting businesses and it is worth highlighting it is for 2050. So if you are committed to the 2030 Eastbourne target, then this will not meet it, nor is it intended to. Your comments will have to reflect this.

Alongside East Sussex County Council (ESCC) will be starting on their Local Transport Plan (version 4). It is assumed that this will have similar themes. As in the past it is likely to end up as ‘Business as Usual’ but with the odd tweak.

Here are some extracts from the TfSE plan you might wish to consider

• Designed to deliver a faster trajectory towards net-zero than current trends, including rapid adoption of zero- emission technologies
• Deliver world class and seamlessly-integrated,sustainable urban transport systems (rail, bus,tram, ferry, cycling and walking)
• Great potential for new mobility (e.g. electric bikes and scooters) to boost active travel in the South East.
• Multi-modal and integrated

Carbon emissions are only ‘tailpipe’, also known as ‘Tank to Wheel’. This is the same methodology that is used for Local Authority carbon footprints. So an Electric Vehicle has a zero footprint the same as a pedestrian. It does not include the generation/mining of the power or its transport, the manufacture and disposal of vehicles and any indirect carbon used.

The TfSE Carbon Assessment report from 2020 admits “Even with considerably higher estimates for conversion to electric (a proxy for all zero emission technologies), “electrification” is insufficient in itself to achieve net zero carbon by 2050.

Their ‘Scenario Forecasting Summary Report’ compared Business as Usual to a Growth scenario. However this was written in 2019 and the closest to the current scenario, following Covid, is their digital scenario.

The most significant feature is cars stay the same, an increase in Public Transport and the reduction in walking and cycling (down 17%). In terms of the obesity epidemic and general health this is going in the wrong direction

Current Transport Planning in East Sussex

Most of the carbon neutral agenda for transport comes from the Government though TfSE is in a position to influence some schemes. However it is worth remembering that recent consultations , such as the A22 roundabouts (£40M) had predictions of 25% more traffic by 2039. To a large extent planning will still be based on
• Predict more cars
• Plan for more cars
• Provide for more cars

Comments you might wish to mention on your submission

*Specify actual targets for a modal shift away from private vehicles
*Not always think that the best solution is just ‘one more lane’ . This often creates induced demand
*Priority given to low carbon vehicles and way from the combustion engine. Partly covered by the 2030 petrol and diesel ban.
*Road space and priority should be re-allocated
*Commitment to better, greener and more frequent bus and train services
*Priority given to active travel to reduce congestion, increase exercise and reduce the obesity epidemic
*Bias in favour of new solutions, with lower carbon footprints, such as micro-mobility
*Strategy for freight around the ‘last mile’ and use of hubs to reduce inefficiencies

Author Paul Humphreys – Cycle East Sussex + Bespoke and Eco Action (Transport Group)