Optimism Bias in Transport Planning

Professor Bent Flyvbjerg in his research identified two main causes of misinformation in policy and management: strategic misrepresentation (or lying!) and optimism bias (appraisal optimism). Strategic misrepresentation is the planned, systematic distortion or misstatement of fact in response to incentives in the budget process. Optimism bias is the demonstrated systematic tendency for people to be … Read more

How can you get resources to address transport challenges?

Addressing Transport Challenges – Part 4 Decisions

In previous articles – Strategy, Analysis and Instruments – I described the first three of the steps in addressing transport challenges.

Decisions is the fourth article in this series on addressing transport challenges, here I outline a systematic approach to evaluating transport proposals and presenting a business case to decision-makers.

The decision-making process involves selecting the intervention or package of options that is expected to deliver the best outcome for the investment required, and within resourcing, political and institutional context and constraints.

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What are some of the challenges in evaluating public transport?

The difficulty in the appraisal of public transport projects is well understood.

The main issue relates to accurately identifying and describing the costs and benefits.

Any initiative that improves public transport could be expected to increase public transport use.

Costs are short term (capital infrastructure and vehicles) and long term (operations and maintenance), and low or high cost.

Benefits can be short or longer term, quantifiable in monetary terms or described in qualitative terms and difficult to isolate from a whole range of other factors.

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Show me the money

Our cities are slowing down. Traffic speeds have continued to slow in metropolitan cities over the past 10 years.

This affects mobility increases fuel use and vehicle emissions and makes road based public transport slower and more expensive to operate.

Professionals are facing significant challenges in the provision of mobility and access – a major challenge is insufficient funding for needed transport infrastructure and services.

Yes, we can make better use of the existing infrastructure, by reallocating road space and providing priority to higher value use like freight and public transport. And we can increase throughput by the use of intelligent transport systems technology, such as providing priority at traffic signals, or managing traffic flows by variable speed limits and ramp metering.

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How to ensure the success of smart mobility

 

Measuring smart mobility initiatives is critical to success.

Transport agencies and companies are accountable for the return on investment funds and it is in their interest to demonstrate the success of past investment in moving towards desired transport outcomes, when seeking funding for future programs.

However, post-evaluation of transport projects is rarely conducted.

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Benefit Cost Analysis of transport projects: 9 No-Nos

  1. Failing to state assumptions clearly.
  2. Ignoring costs due to disruption during construction
  3. Showing ‘optimism bias’ in demand forecasts; project costs; downside risks
  4. Not accounting for full costs of base-case (or ‘do-minimum’) option.
  5. Double counting benefits, eg increased land values due to better accessibility
  6. Ignoring the costs of items simply because they do not have been paid in cash, eg opportunity costs of existing land

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Measurement valuation of public transport reliability

Land Transport New Zealand has released a report that explores methods of measuring the value placed on public transport reliability in different contexts in New Zealand.

Reliability relates to an uncertainty in the time taken to travel from the start to the end of a person’s journey. For a public transport journey, reliability can affect users in one of two ways: as a delay when picking up the passenger and as a delay when the passenger is on the service. One or both of these sources of unreliability causes passengers to arrive at their destination at a different time than scheduled.

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Monitoring and modelling travel time reliability

The use of reliability of trip arrival times does not normally form part of network performance monitoring and modelling. Reasons to monitor and model reliability of trip times include:
(a) monitoring the performance of road network;
(b) monitoring the performance of public transport networks and services; and
(c) evaluating future options.

Although some national guidelines point the way regarding reliability valuations (UK, New Zealand and Australia), current practice is somewhat lagging behind recommended approaches. There is considerable evidence from stated preference survey results related to demand estimation for toll roads and public transport projects, that traveller’s willingness to pay, extends to reliability of travel time, especially for time-sensitive trips.

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Improving Traffic Incident Management: Evaluation Framework

The third report of Austroads Project Improving Traffic Incident Management published in January 2007 provides an evaluation framework to assess priorities for new alternatives in traffic incident management (TIM). It involves a literature review of relevant evaluation approaches followed by application to three case studies.It was found that benefit costs analysis (BCA) provides for a … Read more

The Role of Transport Models in Evaluation

The use of transport models to estimate demand for travel in urban transport networks is well established.

Models simulate travel demand between each each origin and destination zone (the study area is divided into analysis zones) and assigns those trips to the road and transit transport networks.

Urban transport models used to predict changes in travel demand resulting from transport system and demographic changes are based on the concept of perceived generalised travel costs.

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