Are cba results robust experiences from the swedish transport investment plan 2010 2021
This presentation is the property of its rightful owner.
Sponsored Links
1 / 10

Are CBA results robust? Experiences from the Swedish Transport Investment Plan 2010-2021 PowerPoint PPT Presentation


  • 55 Views
  • Uploaded on
  • Presentation posted in: General

Are CBA results robust? Experiences from the Swedish Transport Investment Plan 2010-2021. Mattias Lundberg, Maria Börjesson, Jonas Eliasson CTS March 2011. Background. Widespread scepticism: “CBA results are very sensitive to the choice of assumptions and valuations”

Download Presentation

Are CBA results robust? Experiences from the Swedish Transport Investment Plan 2010-2021

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Are cba results robust experiences from the swedish transport investment plan 2010 2021

Are CBA results robust?Experiences from the Swedish Transport Investment Plan 2010-2021

Mattias Lundberg, Maria Börjesson, Jonas Eliasson CTS

March 2011


Background

Background

  • Widespread scepticism:

  • “CBA results are very sensitive to the choice of assumptions and valuations”

  • “Analysts chose assumptions in order to get wanted results”

  • “Forecast assumptions are wrong”

  • Clear signals from Swedish government on the importance of CBAs

  • Do CBAs lead to sound prioritizations?


How important are assumptions and valuations

Forecast Assumptions

(GDP, population, etc)

Forecast Model

(Sampers, Samgods or similar)

Effect Models

Valuation, discounting and

compilation

How important are assumptions and valuations?

  • Forecast Assumptions

  • Forecasted effect

  • Valuations


1 importance of general scenario assumptions

1. Importance of general scenario assumptions

Land use (population and employment), macro economy, vehicles, time tables, prices …


Importance of object specific assumptions

Importance of object specific assumptions

  • Land use

  • ex E4 Umeå (-0,4 or -0,2)ex Bypass Sth and Roslagspilen

  • Congestion charges

    • ex Marieholmstunneln (+0,2 or -0,5)

  • Rail timetables

    • Definition of ”with” and ”without” investment very important


2 most important deficits of current cba methodology 1

2. Most important deficits of current CBA methodology (1)

  • Valuing improvements of perceived urban environment

    • Large part of benefit for bypasses and tunnels not caught – no general solution

    • Benefits underestimated

  • Forecasting effects of capacity improvementsin congested road systems

    • Shortcomings in static assignment models – solvable

    • Benefits underestimated

  • Forecasting effects of measures that reduce train delays

    • Applicable methods missing – solvable?

    • Benefits under- and overestimated


Most important deficits of current cba methodology 2

Most important deficits of current CBA methodology (2)

  • Forecasting and valuing improvements for freight transport

    • Esp. rail capacity improvements

    • Simplified cost functions, deterministic model, uncertain valuations etc – partly solvable

    • Benefit estimates uncertain

  • Wider economic benefits

    • No official method in Sweden – not solvable, but could do better

    • Benefits underestimated with approx. 10-15% – for some investments


3 importance of valuations

3. Importance of valuations

Official valuations

Relative weights of benefit types

Differentiated values of time


The effect of valuations on rankings

The effect of valuations on rankings

  • The relative weight of benefit types hardly affects rankings

  • Rule of thumb: doubling the weight of a benefit type changes around a tenth of a given top ranking list

  • Differentiated VoT – even smaller changes


Conclusions

Conclusions

  • CBA rankings are surprisingly robust

    • Doubling the oil-price, the freight benefits or the business time valuation hardly changes the ranking

    • Rail timetables and congestion charges important

    • For the design – and NBIR in absolute terms – assumptions can be more important

    • ... Also for analyzing policy instruments

    • Largest shortfall is missing methods for forecasting effects – and valuation of urban environments

    • Increased reliability trains, reduced road congestion, capacity improvements freight railways

  • Ranking very robust wrt valuations

    • Traffic safety rather important – small share of total benefits, large for some projects

    • Differentiated VoT does not even affect balance btw road and rail

    • VoT for non-work trips more important – since more trips than work and business

  • Decision makers can trust CBAs will lead to sound prioritizations

    • The top-ranked investments are more or less the same in all sensitivity analyses

    • CBAs should not be the sole decision criteria


  • Login