PUBLIC INQUIRY QUESTION

Transcription

1 M4 Corridor around Newport PUBLIC INQUIRY QUESTION REFERENCE NO. : PIQ/091 RAISED BY: Tim Gent of St Modwens DATE: 09/05/2017 RESPONDED BY: Bryan Whittaker and Stephen Bussell DATE: 15/05/2017 SUBJECT: INRIX Cost of Brynglas Congestion Report 1. Mr Gent of St. Modwen cited an article published in the South Wales Argus on 6 th May 2017 concerning INRIX congestion data for the Brynglas Tunnels. The inspectors requested WG comment on the INRIX analysis and copies of the associated press reports. RESPONSE: The article (Appendix 1 to this PIQ) cited analysis undertaken by INRIX, a company which specialises in collecting and analysing data on transport and mobility. The South Wales Argus article is in turn based on a BBC report published on their website on the 5 th May Key findings of INRIX were as follows: The stretch of motorway between Junctions 25 and 26 (incorporating the Brynglas tunnels) is the fourth most congested stretch of urban motorway in the UK and would be ranked within the top 50 traffic hotspots in Europe. Over a 12 month period, INRIX identified a total of 1,477 traffic jams or about four traffic jams per day. The longest traffic jam identified at this section resulted in a queue of over 14 miles on the eastbound carriageway stretching back to Magor. The longest duration of a queue was eight hours. INRIX estimated that, over a 12 month period, congestion cost drivers a total of 31m in lost time. The Welsh Government has contacted INRIX who has confirmed that the information reported in the article is correct but have provided further explanation of their methods and findings. INRIX confirmed that data for the Brynglas tunnels was extracted following a request from the BBC. Data The analysis was based on the INRIX Roadway Analytics dataset. The dataset is drawn from a number of sources including satellite navigation devices and mobile phone data. This allows INRIX to analyse traffic speeds on particular sections of the network and to identify where and when congestion has occurred. INRIX considered the section of motorway, in both directions, 1 wales south east wales

2 between Junctions 25 and 26 of the M4. Data was extracted for a 12 month period between April 1 st 2016 and March 31 st Measurement of Congestion As noted above, INRIX identified a total of 1,477 incidents of congestion between Junction 25 and 26. INRIX define congestion as a period in which average traffic speeds fall below 5% of the reference speed for a period of at least 2 minutes. The reference speed is intended to represent free flow conditions and is calculated as the 65 th percentile of a sample of observed traffic speeds for that particular section of the network. For each period of congestion, INRIX is able to identify the length of the queue that results and the duration of the incident of congestion. INRIX explained that the dataset registers an incident of congestion where the queue head (the start of the queue) is located between Junction 25 and Junction 26. Therefore, there will also be occasions where an incident elsewhere on the M4 causes queues which stretch back to Junctions 25 to 26. Such incidents are excluded from the INRIX analysis. Comparative Analysis In order to allow a comparison of different sections of highway, INRIX has developed a traffic Impact Factor. The Impact Factor is an index score calculated using the following formula: Impact Factor = No. of Incidents of Congestion * Average Queue Length * Average Duration It is the Impact Factor which INRIX used to identify where the M4 J25 26 ranks against a sample of other urban motorways. A number of considerations need to be taken into account when interpreting INRIX finding that the M4 J25 to J26 is the fourth most congested stretch of urban motorway in the UK and within the top 50 bottlenecks in Europe: Levels of congestion at the Brynglas tunnels have been compared against congestion on the highway networks of cities included in a November 2016 INRIX report: Europe s Traffic Hotspots: Measuring the Impact of Congestion in Europe. The Traffic Hotspot report included a sample of 123 cities across 19 European countries 2. Only cities with a population of more than 250,000 were included and therefore Newport was not included in the original analysis. A total of 21 UK cities were included. Therefore, the interpretation of the BBC article is that, had the M4 J25 to 26 been included in the European Traffic Hotspot analysis it would have ranked fourth amongst sections of motorway within these cities. INRIX also confirmed that, had the M4 J25 to 26 been included in the European Traffic Hotspot analysis it would have ranked within the top 50 bottlenecks in Europe. The European Traffic Hotspot analysis is based on one months data for September This differs from the data for the M4 J25 to 26 which is for a 12 month period. INRIX stated that, whilst the methodology used to calculate the Impact Factor is the same, the ranking suggested in the BBC report should be treated with caution because traffic conditions can vary from month to month. Costs of Congestion INRIX has estimated the costs to users of congestion on the M4 J25 to 26. This represents the costs of delays to users in terms of increased travel times. To generate these estimates, INRIX has assumed that, in the absence of congestion, the free flow or reference speed would be achieved by users. Costs of delays have been monetised by applying WebTAG Values of Time. Values of time applied are the new values of time which are equivalent to those used in the 2 Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Hungary, Italy, Luxembourg, Netherlands, Norway, Poland, Spain, Sweden, Switzerland, and United Kingdom

3 December 2016 Economic Appraisal Report. Because the analysis applies standard values of time, it does not take account of the fact that users are likely to place a higher value on time lost due to unplanned delays. Linked to this, the estimated cost of delays does not take account of indirect impacts on the economy.

4 APPENDIX 1 Brynglas Tunnels costing motorists 31million in traffic jam queuing time on M4 South Wales Argus / 5 May 2017 / Steven Prince CONGESTION at Newport s Brynglas Tunnels is costing motorists 31million in lost time, with almost 1,500 traffic jams in the space of a year. Figures supplied by the traffic data firm Inrix suggest that there were on average four traffic jams per day between April 1, 2016 and April 31, ,477 in total. The stretch of motorway, running between junction 25 and 26, is also the fourth most congested in the UK, behind three separate locations on the M25. INRIX data shows Brynglas Tunnels to be one of the worst traffic hotspots in the UK, with congesting here costing drivers 31 million in lost time annually, said Dr Graham Cookson, the chief economist of INRIX. Congestion costs the Welsh economy billions, hampers business efficiency, and wastes drivers time and money. The data was published in November 2016, but due to Newport s relative size to other UK cities, it was not included in the initial report. However, when calculated against the data, the Brynglas Tunnels would be among the top 10 of the worst 20,000 traffic hotspots in the UK and the top 50 of the 45,000 in Europe - ceteris paribus. The figures also found that the average distance of the traffic jams around the Brynglas Tunnels was 4.1miles and an average duration of 57 minutes. Despite these issues, congestion is in fact a good problem to have as it s a strong indicator of prosperity and economic growth, added Dr Cookson. However, in order to resolve these issues we must find a solution before the negative effects of traffic detract from the positive causes. The tunnels, the first on a UK motorway, were completed in May 1967, and are celebrating their 50th anniversary in An initial measure to cut travel times and traffic, Dr Cookson added that the plans behind the proposed 1billion M4 Relief Road could help to reduce the congestion between junctions 25 and 26. Unfortunately for those using the Brynglas Tunnels, the geography of the area and the construction of the tunnel means congestion here is difficult to tackle.

5 Hopefully, the M4 Relief Road plans will reduce both the frequency and the length of the queues at this traffic hotspot, added Dr Cookson. The two longest recorded traffic jams on the M4 were 14.52miles on October 3 on the eastbound section, after a lorry broke down with car tailing back to junction 23A. Meanwhile, on the westbound side, the longest jam in terms of duration was an 8.4mile queue between the hours of 10am and 6pm on October 24.