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Maidstone Joint Transportation Board

17 April 2019


Maidstone Bridges Gyratory – Post Scheme Monitoring


Decision Making Authority

Kent County Council/Maidstone Borough Council

Lead Director

Simon Jones

Lead Head of Service

Tim Read

Lead Officer and Report Author

Russell Boorman/Lee Burchill

Wards and County Divisions affected

Wards: Maidstone Central/High Street/Bridge/Fant  

Which Member(s) requested this report?




This report makes the following recommendations:


That the report be noted.








Maidstone Joint Transportation Board

17 April 2019

Maidstone Bridges Gyratory – Post Scheme Monitoring




1.1       This paper provides an overview of the ‘One Year After Opening Report’ for the Maidstone Bridges Gyratory scheme submitted to the South East Local       Enterprise Partnership (SELEP) which is currently being reviewed by an     independent evaluator.


1.2                  The contents of this report should be treated as ‘draft’ as they may change      during the assessment process.  The ‘One Year After Opening Report’          provides details of the actual values for inputs, outputs and some       outcomes one year after the scheme opens. 


1.3                  An overall scheme assessment is carried out to review the whole process     of the scheme delivery, from concept to completion.  This provides the    Authority and SELEP valuable information when progressing and assessing          future schemes.


2.          Project Delivery and Milestones:


2.1      A comparison between the ‘planned date of delivery’ and ‘actual date of                delivery’ was included with an explanation of any major discrepancies                            between the planned and actual delivery. 


2.2      It was noted that the biggest discrepancy during the design stage was to     accommodate the requirement to include flood mitigation to the Lower                    High Street and re-design of the ‘at-grade’ crossing.  This extended the                  detailed design delivery but the scheme itself was still delivered one                     month in advance of the planned date.


2.3      The main scheme was delivered under budget and the underspend was                used to enhance an existing PROW LGF scheme to link with the MBG scheme by upgrading the river tow path. 


3.           Risk Mitigation:


3.1     Scheme risks are recorded within a project ‘Risk Register’, this includes potential mitigation and how this reduces those associated risks.  Risks may not materialise during a project, but a planned course of action is recorded in preparation. 


3.2     The Maidstone Bridges Gyratory scheme was no different and the main risk recorded was associated to the diversion of utility apparatus and traffic management requirements to ensure the travelling public were not adversely affected. 


3.3     To provide a greater control of the largest diversionary works, BT Openreach fibre optic cables, a £1 contract was entered into which gave authority to the Principal Contractor to undertake the diversionary works on their behalf.  This allowed the Principal Contractor to resource and programme effectively, reducing the original programme timeframe.


3.4     Constraints in relation to how traffic was to be managed was included in the contract documents. Appointing a contractor that understood these requirements and constraints would benefit the overall delivery of the scheme.  A rigorous contract evaluation was undertaken to ensure the right contractor was selected for the construction phase.  A contractor that was well established in the area and understood the constraints of working in such a busy urban area was awarded the contract.  This benefited the travelling public by mitigating the need for exhaustive traffic management during peak hours.   


4.       Project Changes:


4.1        As indicated above, a significant change was the inclusion of flood risk management to the scheme, including the closure and filling of two existing subways and installing a flood gate on the third.  This has provided beneficial improvements to the flood defence for the Lower High Street, where in 2013, businesses and residents suffered devastating flooding when the river overflowed.  The new defences have been designed to cope with the 1in100year occurrence.


4.2        Further changes were made with the inclusion of the tow path renewal.  This not only complemented an existing LGF scheme being delivered, but provided a safer environment for highway users, whilst encouraging leisure activities and potential future riverside events.


4.3        During the construction phase, the ramp and steps to the Lower High Street had to be re-designed.  This was due to the inaccurate utility information meaning what was proposed would have increased the diversionary costs significantly and therefore the more cost-effective option was to redesign.  This provided a more usable area and aesthetically more in keeping with the area and allowed for landscaping to be incorporated. 


4.4        A second element of the design was also changed in the construction phase in relation to the alignment of vehicles traversing St Peters Bridge turning right across the new north bound lanes.  A ‘squarer’ junction was installed with additional lining and signing to prevent any illegal manoeuvres.  This was identified at the regular progress meetings held between the PC, Consultant and Client.


5.    What went well/Lessons Learnt:


5.1 Table 1 identifies what has been recorded as going well and the lessons learnt.







What went well

Lessons learnt

Stakeholder Engagement

Due to the complexity of the scheme and the use of this junction by commuters rather than residents, the engagement had to reach a much wider audience than usual.  A comprehensive communication plan was devised which included the use of buses for advertising, the PM carrying out radio interviews, advertisements in local publications, public events in the local town centre, business briefings and Member specific briefings.

The use of social media and technology played an important role in disseminating information quickly and effectively.  Twitter accounts are now becoming more commonly used on projects and a live link can be included on the corporate website to give up to date information.


Standard OJEU procurement was utilised for this project.  This allowed us to engage with local contractors who would have a working knowledge of the area giving benefit to the submission. 

Due to the working restrictions and timescales for completing the works, the mobilisation period was significantly reduced meaning insufficient time for set up prior to commencement.  Suitable timings must be made available for procurement timescales and contingency allowed for.

Availability of internal resources

The Major Capital Programme Team has increased in numbers and therefore have suitable internal resources to carry out delivery of all schemes within their responsibility. 

Internal departments that feed into the design need to be kept updated at all stages of the design and included in steering group meetings to ensure delivery of the project.

Table 1:  Lessons Learnt.



6.0  Road Safety:


6.1  As previously reported to the board, data recorded to date suggests that road safety has been improved following the implementation of this scheme; table 2 identifies the personal injury crash trend for the previous 5 years.  


Recorded Year


















      Table 2 Crash Trend.






6.2    In 2017, the first full year following operation of the new north bound lanes, the recorded crash data is as follows:


·      3 slights

·      0 serious


6.3   This equates to a 51% reduction in ‘slight incidents’ over the average in the previous 5 year period. 


7.0  Traffic Impacts:


7.1     Weekday traffic surveys were carried out on Wednesday 13th March 2019. Weekend surveys were carried out on Saturday and Sunday 16th-17th     March 2019.


7.2     Surveys were carried out by Automatic Number Plate Report (ANPR) to         provide full path information for vehicles using the gyratory.  Queue length       data was collected by lane at the same time as the ANPRs.


7.3     As the traffic signals operate using variable timings to optimise for traffic,   traffic signal timing information for each stop line was collected over the      survey period.


7.4     Analysis of the survey data was carried out to identify the weekday and      weekend peak periods. These were:


                • Weekday AM: 07:30 - 08:30

          • Weekday PM: 16:00 - 17:00

          • Saturday: 12:30 - 13:00

          • Sunday: 12:15 - 13:15


7.5     Prior to running the LinSig models, a full review of both the existing and     proposed models were carried out. This highlighted a number of areas    where the models did not reflect the previous or new layout.  This is due       to alterations made to the alignment during the detailed design process.


7.6     The initial analysis identifies that some traffic movements see a reduction in travel time through the gyratory, predominately vehicles travelling northbound, and improvements for vehicles travelling through the gyratory from the A20 and St Peter’s Street. These are currently recorded as positive benefits of the scheme delivery.


7.7   The initial analysis also indicates that there may be a negative effect for vehicles travelling in a southbound direction.  However, it must be noted that  additional information is being sought and further assessments will be completed for all movements, comparing the existing situation with a ‘do nothing’ scenario (without the improvement).  


8.0  Conclusion:


8.1   The Maidstone Bridges Gyratory improvement scheme continues to be monitored against the original objectives that were set out in the SELEP business case. Since opening there have been very few negative comments and the system continues to be monitored with minor adjustments made to the traffic signal timings where necessary to maximise its’ performance.


8.2   The purpose of the ‘One Year After Opening Report’ is to review the scheme delivery and establish any early benefits that may have been realised.


8.3   KCC will continue to work with SELEP and the Independent Technical Evaluator to review the available transport data and establish the outcomes and impacts of the scheme following delivery. This will also include a further post scheme monitoring review after 3/5 years.