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RHD Operational Procedure Planning and Maintenance Wing
Economics - Feasibility Studies Division
OP/EC/3.2 - Traffic Studies
Purpose and Scope :

The Economics Circle with need to conduct traffic studies for the following reasons:

Complex economic feasibility studies and appraisals where there will be significant re-assignment of traffic on the road network (such as an urban bypass);

Development of Traffic forecast model

Assessment of traffic volumes on toll roads taking into account the toll elasticity of demand;

Assessments of road and junction capacity and strategic studies of traffic movements.

The traffic studies could be conducted anywhere in the county and will include traffic surveys, data analysis, matrix building and traffic modelling.
Definitions :

Toll Elasticity of Demand the responsiveness of traffic demand to toll charges

Traffic Matrix a table of the origins and destinations of person and/or vehicle trips for a particular area

Average Annual Daily Traffic (AADT) the most commonly used unit of account for traffic volumes; equal to 1/365 of the total annual traffic volumes

Origin/Destination Survey (O/D) interview survey used to establish trip-making profiles, usually of a sample population.

Manual Classified Count (MCC) traffic volume count conducted by hand tally of observed traffic movements classified into vehicle categories by direction and time period

Travel Time Survey (TTS) survey of existing vehicle travel times normally conducted using the moving observer technique
Responsibility :

Chief Transport Economist approves survey programme and budget

Executive Transport Economist Feasibility Studies Division designs and plans the field surveys, analyses the data and runs the traffic model

Assistant Transport Economist Road User Cost Division conducts field surveys
Method :


The request for a traffic study will normally be received a part of the request to conduct a feasibility study as part of the PCP preparation process. The CTE and ETE FSD will review existing data and define what additional data is required. They will also define what level of analysis is needed and if a traffic model needs calibrating. They will write terms of reference for the works to be undertaken either by the Circle or Consultants. The ETE-FSD will define a budget for the study which will agreed by the CTE.


The CTE and ACE Planning and Maintenance will decide whether the works will be conducted internally or externally and agree a budget. If the works are to be conducted externally consultants will be appointed in accordance with OP/PC/2.4.


The traffic surveys may include traffic volume (usually manual classified counts), origin/destination, and travel time surveys. If conducted in-house the Assistant/Sub Assistant transport economist will hire the survey personnel required, train the team and conduct the surveys according to the RHD traffic counting manuals.


The traffic data will need to be processed and analysed in accordance with international best practise, particularly for complex schemes such as by passes in urban areas. No RHD procedures existed at the time of writing. Outputs will include link traffic volume AADT; average link speeds; Origin/Destination matrices.


If a traffic model is calibrated a validation report will have to agreed by the CTE and ETE-FSD before forecasting is undertaken.


The results of the study will be prepared in hard and soft copy and distributed to the requested and ACE Planning and Maintenance.
References :

HDM-4 Manual published by TRL

RHD Classified Traffic Counts Manual October 2001

Economics Working Paper E2 National Traffic Census

Economic Working Paper E3 Automatic Traffic Counters

Economic Working Paper E4- Traffic Congestion Modelling
Procedure Flowchart :

The procedure flowchart for this procedure is detailed below -




For duties associated with each grade of personnel see


Updated on : 1/12/2003