Road Traffic Works - Old Gore crossroads
Case reference EIR2021/00091
Published 18 November 2021
Request
There is a proposal to install traffic lights at the Old Gore crossroads. I understand that any major work of this kind requires a Feasibility Study to be carried out by Herefordshire Council or Balfour Beatty to consider all of the options and costs before making a decision. I would like to see a copy of this report or, at the very least, a summary report showing the options considered and the costs associated with each, showing the decision process that was undergone to reach the conclusion.
Response
The Service Area have provided the below rationale considered for the scheme:
The A449 Old Gore Cross roads has been identified by Herefordshire Council as one of the most prolific road traffic collision sites on the county road network over many years. In line with Herefordshire Councils agreed road safety strategy as documented in our current Local Transport Plan (based upon national best practice guidance) this has resulted in numerous low cost safety interventions involving various improvements of signs, lines, road markings and resurfacing during this time, in a bid to better influence driver behaviour and improve overall road safety over the years. Notwithstanding these works and the various ongoing reductions in collision numbers they have brought about compared to previous periods, during the most recent 5 year period from February 2016 to January 2021 there have been 9 reported personal injury collisions including 1 fatality, 2 serious and 6 slight severity incidents. In light of this, the decision to proceed with the design and implementation of a major improvement scheme has involved the consideration of many elements, not least of which is the need to robustly control the movement and speed of existing main road traffic.
Given that the use of existing signing, lining and marking techniques have now been exhausted, initial options considered to improve the junction included; a) construction of a roundabout, b) signalisation of the junction and c) installation of VAS signs on the A449 to advise of crossing vehicles. In consideration of each of these options the following summaries outline the accident investigations, design and thought processes used throughout the process:
Option a) Roundabout
In an ideal world the provision of a roundabout would be the desired solution, however initial investigations highlighted existing topography and physical constraints of the site layout that were found to present significant difficulties when attempting to achieve a design compliant with current standards. Primarily the vertical alignment differences between the existing B4224 side road approaches and main A449 through route would require extensive physical re-profiling involving major earthworks and new road construction, in order to achieve gradient profiles in compliance with Design Manual for Roads & Bridges (DMRB) standards for new roundabout design. It was also apparent that significant areas of additional land would be required on all four corners of the junction, in order to ensure that both inter-visibility splays between entry arms and required horizontal alignment curvature could be provided, in line with current design standards. Following a knowledge based preliminary engineering suitability assessment considering all these aspects, based upon considerable engineering experience it became clear that the roundabout option would be cost prohibitive due to both aspects mentioned, and as such it was decided not to progress further to detailed design in order to mitigate additional costs.
Option b) Signalisation
The provision of a traffic signal controlled junction design, compliant with current standards, can be achieved within the existing site constraints, needing only relatively modest change in alignment and minimal land take. This option would be considered to achieve the goal of physically controlling main road traffic speed and movement, with substantially less intrusion on the surrounding land compared to the roundabout option, producing a much more cost effective solution. Whilst street lighting provision is a requirement of current design standards when dealing with a conflict zone, this is also the case with roundabout design. One benefit of the more compact nature of a signalised junction arrangement (compared to a roundabout) is that the numbers of lighting columns required to ensure compliance is reduced, which lessens the potential environmental concerns around light pollution in the surrounding countryside. With this in mind, current lighting design utilising modern led lantern and automated dimming technology also helps to further minimise and mitigate the light scatter associated with older technology (such as low pressure sodium bulbs) producing a much more effective, energy efficient and environmentally friendly solution, whilst ultimately improving road safety. The proposal would also include the installation of Microprocessor Optimised Vehicle Activation (MOVA) technology, as part of a well-established strategy for the control of traffic signals at isolated junctions which monitors approach flows and minimises the wait times on all arms.
A further consideration undertaken when considering a potential signal scheme relates to the historical success Herefordshire has witnessed with the installation of two previous rural (at the time) signal controlled crossroad junction installations. The A438 junction with the A417 Trumpet crossroads introduced circa 2000 and the A4103 junction with the A417 Newtown crossroads introduced in 2004, both continue to perform well in relation to ongoing recorded personal injury collisions. Over their post treatment life span of 21 years for the A438 /A417 and 17 years for the A4103 / A417, they have recorded an average of 0.1 collision per year and 0.4 collision per year respectively. When compared to the current performance of 1.8 collisions per year for A449 Old Gore crossroads, this illustrates potential reductions in average collision numbers per year of between 78% and 94%.
Option c) Provision of Vehicle Activated Signing
In consideration of the use of Vehicle Activated Signing (VAS), whilst this would be significantly less expensive, real world experience of this technology shows that the required "physical" control of vehicle movement required in this location is unlikely to be achieved, as this primarily relies on gaining a "psychological" influence over driver behaviour. They can broadly be considered to utilise the same principles as existing "standard" high visibility signing technology, with some additional benefit attributable to their ability to specifically highlight situations to individual vehicles. However, they do not guarantee any additional compliance with the message they are designed to give, and when taking account of the restrictions placed by the Traffic Signs Regulations and General Directions (TSRGD) 2016 on what may actually be displayed within the current legislation, this further limits what they could be hoped to achieve. When taking these considerations into account and given the behavioural patterns witnessed during extensive collision investigations, it was considered that compliance by drivers (and subsequent benefits) would be limited overall and therefore the option was discounted.
Taking all the above elements into account, it was therefore proposed that the design and installation of a traffic signal scheme would likely present the most cost effective solution, and this was taken forward to detailed design.
Following detailed design, the associated costs of the scheme were assessed using an industry standard (but relatively simple) First Year Rate of Return calculation that considers the Value of Prevention (VoP) costs attributable to all severities of road traffic collisions by the Department for Transport (DfT), and examples of these can be found in the DfT's annual publication: Reported Road Casualties Great Britain. In simplified terms, using an assumption that an untreated location could potentially continue with the same levels of collisions and casualties exhibited by the preceding baseline period (5 years in this case) it allows for both an "optimistic" (saving all future collisions) and "pessimistic" (realistic low number saved) outcome to be assessed against the investment required. In the case of a signal scheme for Old Gore crossroads this ranged from a worst case of 45% return on investment in the first year after completion, to a 135% return in the first year using the "optimistic" model. Financially, both of these outcomes would be considered to exhibit significant benefit, with the scheme effectively becoming cost neutral in a little over 2 years for the worst case, and less than 1 year for the optimistic scenario.
From a communications perspective, both the Ward Councillor and local Parish Council's within the vicinity have been involved in numerous discussions regarding the potential scheme and its installation. Overarching support for the principals of the scheme has been forthcoming from all parties throughout the process.
Overall, the above should demonstrate that both Herefordshire Council and Balfour Beatty have undertaken all potential considerations that could reasonably be expected as a competent Highway Authority, in the development and implementation of this scheme. Whilst the inevitable change and subsequent disruption during works often proves a contentious issue, it is hoped all would agree it is a small price to pay for the prevention of the loss of life and improvement of road safety on roads within our County.
Documents
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