Name of Indicator:

Nominal Travel Speed (Urban)

Code:

NTSU

Measurement Area:

Road System Performance – Technical Efficiency.

Type of Measure:

Outcome – Travel speed

Purpose:

Establish a base system capability for measurement of level of service to road user.

Goal:

Evaluate network.

Description:

Conversion to average nominal travel speed (NTS) of aggregation of nominal trip times per kilometre at the speed limit on a representative sample of arterial roads and freeways in the urban metropolitan area (NTT) in order to establish base system capability for measurement of level of service to road users.

Definition:

where:

and:

j     =  link number (j = 1,2, …,x)

x    =  number of links to be aggregated

N_j  =  nominal travel time of link j (mins)

      L_j   =  length of link j.

Units:

Km/hr

Frequency of Collection

Annual.

Assumptions/ Limitations

It is assumed that, for each State authority, the network which is being monitored is a true representative sample of routes and travel environments within the metropolitan area.

Changes to initial specifications

The initial specification called for measurements to be made in the three time periods of the day (i.e. AM Peak, PM Peak,0ff Peak). As the Nominal Travel Time is based on the trip time of the links at the specified speed limit only the measurement of speed limit and length of link is required.

Methodology Summary

Definition of Network to be Monitored

The monitored network is to be defined so that it provides a representative sample of routes and travel environments within the metropolitan area, and is to be based on the arterial road network (i.e. freeways, primary and secondary arterials).

Analysis

The following analysis process is to be carried out for each of the three collection periods (i.e. March/April, July/August and October/ November). The Nominal Travel Time (NTT) in minutes/kilometre is calculated by aggregating the nominal travel time of the links at the speed limit. This is done using the following formula:

where:

and:

j     =  link number (j = 1,2, …,x)

x    =  number of links to be aggregated

N_j  =  nominal travel time of link j (mins)

       L_j   =  length of link j.

Reporting

Values of NTT are to be reported for the full financial year. These will be calculated by averaging the values from each of the three collection periods (i.e. March/April, Jul /August and October/ November.

Further Developments

A Nominal Travel Speed indicator is currently being developed for Rural Inter-regional Roads