National Transport Model Research Articles

Cross-border Car Traffic in Dutch Mobility Models

Cross-border travel generates a substantial amount of mobility near the borders, but is not a large percentage of total Dutch mobility. However in the border regions of the country, these flows are important. For the Dutch national transport model LMS, O-D matrices are required that include cross-border car travel. This is a challenging task, due to scarcity of data. First, a production model (by travel purpose) is used to calculate the total production of car journeys. Next, these journeys are distributed over domestic and foreign destinations using a simplified destination choice model. From the resulting matrix, domestic journeys are removed and only the border crossing journeys are kept. Domestic journeys are then replaced by the results of the existing much more detailed mode-and destination choice models. The new models are estimated on the Dutch national mobility survey (MON) and are of reasonable quality. The predicted numbers of border crossing journeys to Belgium and Germany are lower than the numbers from traffic counts, and therefore an additional calibration to count data totals is carried out. The results indicate that for commuting the resistance to cross the border is equivalent to 35 (Belgium) or 46 (Germany) minutes extra travel time. Also for all other travel purposes in the model, it is found that the border resistance for journeys to Belgium is smaller than that for journeys to Germany, which can be explained by the additional factor of language difference. The smallest border resistance for both countries is found for shopping journeys.

Generating synthetic baseline populations from register data

The paper presents a population synthesiser based on the method of Iterative Proportional Fitting (IPF) algorithm developed for the new Danish national transport model system. The synthesiser is designed for large population matrices and allows target variables to be represented in several target constraints. As a result, constraints for the IPF are cross-linked, which makes it difficult to ensure consistency of targets in a forecast perspective. The paper proposes a new solution strategy to ensure internal consistency of the population targets in order to guarantee proper convergence of the IPF algorithm. The solution strategy consists in establishing a harmonisation process for the population targets, which combined with a linear programming approach, is applied to generate a consistent target representation. The model approach is implemented and tested on Danish administrative register data. A test on historical census data shows that a 2006 population could be predicted by a 1994 population with an overall percentage deviation of 5–6% given that targets were known. It is also indicated that the deviation is approximately a linear function of the length of the forecast period.

Dry deposition of reactive nitrogen to European ecosystems: a comparison of inferential models across the NitroEurope network

Abstract. Inferential models have long been used to determine pollutant dry deposition to ecosystems from measurements of air concentrations and as part of national and regional atmospheric chemistry and transport models, and yet models still suffer very large uncertainties. An inferential network of 55 sites throughout Europe for atmospheric reactive nitrogen (Nr) was established in 2007, providing ambient concentrations of gaseous NH3, NO2, HNO3 and HONO and aerosol NH4+ and NO3− as part of the NitroEurope Integrated Project. Network results providing modelled inorganic Nr dry deposition to the 55 monitoring sites are presented, using four existing dry deposition routines, revealing inter-model differences and providing ensemble average deposition estimates. Dry deposition is generally largest over forests in regions with large ambient NH3 concentrations, exceeding 30–40 kg N ha−1 yr−1 over parts of the Netherlands and Belgium, while some remote forests in Scandinavia receive less than 2 kg N ha−1 yr−1. Turbulent Nr deposition to short vegetation ecosystems is generally smaller than to forests due to reduced turbulent exchange, but also because NH3 inputs to fertilised, agricultural systems are limited by the presence of a substantial NH3 source in the vegetation, leading to periods of emission as well as deposition. Differences between models reach a factor 2–3 and are often greater than differences between monitoring sites. For soluble Nr gases such as NH3 and HNO3, the non-stomatal pathways are responsible for most of the annual uptake over many surfaces, especially the non-agricultural land uses, but parameterisations of the sink strength vary considerably among models. For aerosol NH4+ and NO3− discrepancies between theoretical models and field flux measurements lead to much uncertainty in dry deposition rates for fine particles (0.1–0.5 μm). The validation of inferential models at the ecosystem scale is best achieved by comparison with direct long-term micrometeorological Nr flux measurements, but too few such datasets are available, especially for HNO3 and aerosol NH4+ and NO3−.

The Usefulness of Transport Models in Swedish Planning Practice

This paper presents some experience from using transport models in Swedish planning practice. First we outline three recent examples of planning settings in which transport models have been put to extensive use. For the Swedish ‘national’ transport plan for the period 2010–2021, which was recently finished, the national transport model SAMPERS was used to compute costs and benefits for many investment projects. The second example concerns the ‘regional’ plan for Stockholm, where a similar but less detailed model, LuTRANS, was used to investigate different transport and land use scenarios. The third example discusses a recent study on the feasibility of introducing congestion charges in Gothenburg, where both a fixed demand approach and SAMPERS were used. Furthermore, the paper tries to help identify what model development can do to help improve the production of decision support through modelling. We argue that effectiveness and efficiency are key. The first is characterized by making sure that the right things are done and that they are done right. Efficiency, which is less often discussed in the literature, is framed in terms of doing things on time and doing them only once. The managing organization around a national model system can play an important role in helping users avoid redundant work. It is also a good idea to resist the temptation to use up all improvements in computing power for additional model features. There are many worthwhile analyses that are never done because of time constraints.

Isa Town Gate interchange, Bahrain

The Bahrain Ministry of Works roads directorate and Hyder Consulting undertook a national transport model in 2002 in which traffic congestion was identified and future 2021 traffic flows were estimated. Strategic improvements were identified to improve traffic flow and make allowances for future increases in traffic volumes. The Isa Town Gate interchange was an existing roundabout with a five-leg junction in an urban setting with two major highways: Sheikh Salman Highway and Al Estiqlal Highway. This paper details the design of the £66 million project from concept to tender and also expands on the construction progress. Execution of the project modified the existing Isa Town Gate roundabout into a three-level grade-separated interchange. The option chosen was a three-level grade-separated junction with a free-flow flyover and underpass for the major highway routes. The existing roundabout was replaced with a complex split-traffic signalised junction accommodating all movements. The flyover consisted of two non-parallel curved bridge decks 2·4 km long of glued segmental prestressed concrete viaducts. An overhead launching gantry was specified to minimise traffic management. The underpass was designed as a diaphragm-walled U trough but was later varied to a ground-anchored solution. Construction commenced in October 2007, and is due for completion in mid-2010.

A micro-simulation model of shipment size and transport chain choice

Practically every international, national or regional freight transport model system in the world lacks explicit treatment of logistics choices (such as shipment size considerations or the use of distribution centres). This paper deals with the development of a new logistics model and its application within the national freight model systems of Norway and Sweden. This logistics model operates at the level of individual firm-to-firm (sender-to-receiver) relations and simulates the choice of shipment size and transport chain for all (several millions) these relations within the country, export and import. A logistics model with deterministic cost minimisation has been constructed for both Norway and Sweden. The full random utility logistics model has not yet been estimated on disaggregate data, but this is planned for both countries. For Sweden, more limited disaggregate models for the choice of mode and shipment size have been estimated.

A model of annual orographic precipitation and acid deposition and its application to Snowdonia

A model of orographic rainfall has been used to estimate annual precipitation and acid wet deposition at a 1 km resolution for the Snowdonia mountains in North Wales. Comparison with measurements and existing rainfall maps of the UK showed that this approach was successful in reproducing the high annual precipitation peaks of up to 4000 mm annually that occur in this area. At 13 out of the 17 measurement sites, the modelled annual precipitation differed from long-term annual average measurements by no more than 25%. The process model was compared with a procedure used to map wet deposition of pollutants across the United Kingdom at a 5 km resolution. Significant differences between the two deposition data sets were apparent. With the mapping procedure, maximum wet deposition was correlated to areas of high precipitation in the northeast of the domain. With the process model, however, maximum deposition was observed over the smaller hills in the southwest of the domain, the first orographic barrier reached by the air mass in south-westerly flow. High exceedances of critical loads for acidic deposition to soils were calculated using the mapping procedure and found to be due to the high annual precipitation in Snowdonia. The seeder–feeder model represents a useful tool, which could be used for estimating annual wet deposition of pollutants and exceedance of critical loads in hill areas at a much finer resolution than the national transport models and deposition mapping routines that are commonly employed in the United Kingdom.

Planning for an unpredictable future: Transport in Great Britain in 2030

This paper describes a research study, which explores alternative future scenarios for Great Britain in the year 2030 and the implications these have for travel demand and transport provision. Five alternative future scenarios are represented in the GB national transport model and forecasts are obtained for trip making, traffic levels, congestion and emissions in 2030. For all scenarios it is expected that there will be significant traffic growth. Traffic growth is restricted most in scenarios including distance-based road charging on motorways and trunk roads. However, congestion and carbon dioxide emissions are most effectively limited in scenarios with congestion-based road charging, major improvements to urban public transport and investment in new fuel technologies and in improving engine efficiency.

National and International Freight Transport Models: An Overview and Ideas for Future Development

This paper contains a review of the literature on freight transport models, focusing on the types of models that have been developed since the 1990s for forecasting, policy simulation and project evaluation at the national and international levels. Models for production, attraction, distribution, modal split and assignment are discussed. Furthermore, a number of ideas for future development, especially for the regional and urban components within national freight transport models, are included.

The effects of motivational factors on car use: a multidisciplinary modelling approach

Current transport models usually do not take motivational factors into account, and if they do, it is only implicitly. This paper presents a modelling approach aimed at explicitly examining the effects of motivational factors on present and future car use in the Netherlands. A car-use forecasting model for the years 2010 and 2020 was constructed on the basis of (i) a multinominal regression analysis, which revealed the importance of a motivational variable (viz., problem awareness) in explaining current car-use behaviour separate from socio-demographic and socio-economic variables, and (ii) a population model constructed to forecast the size and composition of the Dutch population. The results show that car use could be better explained by taking motivational factors explicitly into account, and that the level of car use forecast might change significantly if changes in motivations are assumed. The question on how motivational factors could be incorporated into current (Dutch) national transport models was also addressed.

Evolving role of models in transport planning

The recent profound change in the role and basis of the UK National Road Traffic Forecast and the current efforts to develop a more policy-oriented National Transport Model are described. The role of models which seek to represent aspects of travel behaviour in detail, and are used for detailed design of schemes and policies, is contrasted with that of simplified strategic models which lay people and professionals can use to test policy options and identify the most promising ones. The paper explores the role and reputation of models in the transport planning process and suggests that models are more often used to justify than to challenge predetermined policies; model predictions which conflict with orthodox policy, or with the analyst's intuition, are generally accepted most reluctantly. A model's popularity is likely to have more to do with its presentation, interface and pedigree than its accuracy or track record. More sensitivity analysis of model coefficients and input parameters is needed.