Project » Cost effectiveness of MIDAS
| Section: |
Traffic Management |
All projects in this section |
| Start-End Date: |
01/1998
- 02/2002
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| Project status: |
Completed |
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| Publication Status: |
Not Published |
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| Project value: |
£140,000 |
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| Project Contractor: |
TRL |
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| HA Project Sponsor: |
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| Reference: |
3/161 |
Introduction:
Since 1989 an Automatic Incident Detection (AID) system has been in operation on an 83km section of the English M1 motorway. The system was designed by the Agency to detect and locate slow moving or stationary traffic automatically, on the northbound and southbound carriageways. Warning signs, in the form of an advisory 50mph speed limit, can then be set upstream of the queues to advise drivers to reduce speed. Once normal flows are re-established the system automatically turns off the warning signs. A more up-to-date system known as MIDAS was installed in 1997 on the M25 controlled motorways section. This project is designed to undertake a study of accidents before and after the installation of automatic incident detection systems on the M1 and M25. Each of the potential benefits of the AID system are being examined together to obtain an overall figure for the cost saving per year following the installation of an incident detection system.
Project Objectives:
The objective was to establish the quantified accident and congestion reduction benefits of the existing automatic incident detection pilot system on an 83km length of M1. The system was a forerunner of the current standard for Motorway Incident Detection and Automatic Signalling (MIDAS) and had been installed in Northamptonshire and Bedfordshire in the late 1980s. It therefore presented the opportunity for examining any changes in the long term accident rates and using them to derive the economic benefits. Accident statistics from the remainder of the M1 were used for control purposes.
Having established a modus operandi for the M1 study, similar techniques were subsequently applied to the assessment of the benefits of MIDAS on part of M25, which had been installed after the study length became a Controlled Motorway.
Summary:
The findings of the M1 study were presented in TRL Report 383 of 1998. DETR HETA endorsed the findings and used them to assess the economic benefits of the triple package (incident detection combined with cabling infrastructure and gantry signs). Thus the research enabled the economic case for this investment to be quantified.
The findings of the M25 study are given in TRL Project Report PR/T163/00, of March 2001.
A 6 minute video about the findings, entitled “Queue Ahead” was made by TRL as part of the project. Copies have already been circulated extensively in HA and are held by Information Points.
The M1 research established that total injury accidents were reduced by 18%, (fewer fatal and less serious) based on loop detectors and with central reserve indicators (MS1) at 1km spacing. The total savings aggregate to £94,000 /km of D3 motorway /year. The savings from reduced accidents represent 94% of the total, with savings from reduced congestion the remaining 6%. DETR HETA endorsed the findings and have accepted that the larger variable message signs (MS3) currently being installed, although at increased centres (1.5km), are expected to provide at least the same level of benefits as those already established. This is due to the larger sign and improved visibility, compared with those on the central reserve (MS1).
The outcome is the inclusion in the 10 Year Plan of over 800 km of the most congested lengths of motorways to be installed with MIDAS and the other components of the triple package by March 2005. (Approx. cost of triple package is £0.25m /km.)
MIDAS was installed on parts of M25 (J10 - J15) using portal gantry signs at 1.0 km intervals. Installation was after that length had become a Controlled Motorway, with variable mandatory speed limits. Nevertheless, in liaison with HETA, the opportunity was taken of assessing the benefits, using queue-tail accident comparisons in the two years before and two years after MIDAS installation. It was no surprise that, with the Controlled Motorway already operational, the incremental benefits were much reduced compared with the M1 study. Nevertheless even with this non typical sequence of installations the best estimate is that non-statistically significant benefits are of the order of £21,000 /km /year for the D4-motorway.
Executive Summary:
Project Reports:
Publications:
TRL Report 383, 1998,
TRL Unpublished Report PR/T163/00, March 2001
