Technical Note

Proposed A1060 Junction Improvements, Hatfield Heath Capacity Assessments and Review of Conditions

1 INTRODUCTION

Essex Highways have been approached to assess the potential of upgrading two junctions in Hatfield Heath, the A1060 Road / B183 Dunmow Road and the A1060 Stortford Road / Road. Currently they operate as priority junctions and this study considers whether mini-roundabout arrangements would contribute to improved performance. Figure 1-1 shows the study area.

© Crown Copyright All Rights Reserved 100019602 2014 Figure 1-1: Hatfield Heath Study Area

2 DATA COLLECTION

Manual classified turn counts were carried out on Wednesday 1st May, 2013 at the two named junctions. The data confirmed that the morning peak hour is between 07:45 and 08:45 and the evening peak hour is between 17:00 and 18:00. A summary of the turn counts is included in Appendix A. Junction assessments have been based on this data plus queue length information gleaned from a site visit carried out on Wednesday 15th January, 2014. The site visit enabled a more thorough understanding of current conditions in the area. This is covered in more detail in Section 6.

3 ASSESSMENT METHODOLOGY

In order to properly ascertain the potential of the mini-roundabout proposals, junction assessments to compare their performance against the existing layouts are necessary. Both scenarios have

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Proposed A1060 Junction Improvements, Hatfield Heath Capacity Assessments and Review of Conditions

therefore been assessed using the latest industry software, Junctions 8.0, which was formally introduced in February 2012 and has the capability to model both priority junctions and roundabouts.

In terms of model outputs, the performance and operation of a junction in Junctions 8 is given by maximum queue length in passenger car units (pcus) and Ratio of Flow to Capacity (RFC) for each approach. Generally, where the RFC is shown to be greater than 1.0, the approach is said to have exceeded its theoretical capacity as the number of vehicles arriving at the junction on that particular arm exceeds its capacity. Any approach with an RFC above 1.0 is expected to suffer from notable vehicle queues and delays. An RFC of between 0.90 and 1.0 is usually taken as an indication that an approach has reached its practical capacity and where vehicles will start to experience some delay and congestion. For ease of reference, the tables detailing the assessment findings in this report colour-coded red for RFCs of more than 1.0, amber for 0.90 to 1.0, and green for anything less than 0.90, i.e. within capacity.

4 EXISTING JUNCTION ASSESSMENTS

Table 4-1 and Table 4-2 show the performance of the two existing junction layouts in the AM and PM peak periods. The models have been calibrated according to observed conditions of the Wednesday 15th January 2013 site visit.

RFC Q Length Approach Arm AM Peak A1060 Stortford Road N/A N/A B183 Dunmow Road 0.99 12 A1060 Chelmsford Road 0.05 0 PM Peak A1060 Stortford Road N/A N/A B183 Dunmow Road 0.68 2 A1060 Chelmsford Road 0.09 0 Table 4-1: Current A1060 / B183 Dunmow Road Performance

Table 4-1 confirms that the only noteworthy queue currently visible at the A1060 / B183 Dunmow Road junction is on the southbound Dunmow Road approach. An RFC of 0.99 and a maximum queue length of 12 pcus is recorded in the AM peak. However, no significant delay is apparent in the PM peak.

RFC Q Length Approach Arm AM Peak

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Proposed A1060 Junction Improvements, Hatfield Heath Capacity Assessments and Review of Conditions

RFC Q Length Approach Arm Sawbridgeworth Road N/A N/A A1060 Stortford Road North 0.65 2 A1060 Stortford Road East 0.85 6 PM Peak Sawbridgeworth Road N/A N/A A1060 Stortford Road North 0.58 1 A1060 Stortford Road East 0.63 2 Table 4-2: Current A1060 / Sawbridgeworth Road Performance

Table 4-2 confirms that little delay is currently witnessed at the A1060 / Sawbridgeworth Road junction in either peak period. A minor delay is shown for right turners from the A1060 east arm towards Bishops Stortford. However, the relatively low flows from Sawbridgeworth Road mean that it is minimal and any queue clears rapidly.

5 PROPOSED JUNCTION ASSESSMENTS

Table 5-1 and Table 5-2 demonstrate the modelling results of the proposed mini-roundabout arrangements at both junctions. These are based on the proposed layouts which are included in Appendix B.

RFC Q Length Approach Arm AM Peak A1060 Stortford Road 0.63 2 B183 Dunmow Road 0.65 2 A1060 Chelmsford Road 1.12 27 PM Peak A1060 Stortford Road 0.90 7 B183 Dunmow Road 0.40 1 A1060 Chelmsford Road 0.65 2 Table 5-1: Proposed A1060 / B183 Dunmow Road Mini-roundabout Performance

The results of the A1060 / B183 junction assessment show that the current delay encountered on the B183 Dunmow Road approach in the AM peak is transferred to the A1060 Chelmsford Road approach with a mini-roundabout installed. However, the modelled delay is notably higher with a maximum queue length of 27 pcus possible. The outcome is logical given that there is a reversal of right of way in the new layout proposals; the greater westbound A1060 movements now have to

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give way to southbound movements from the B183 unlike currently where the opposite conditions exist.

In the PM peak, no such delay is encountered. However, a minor delay is modelled for eastbound movements on Stortford Road. This is more attributable to the high demand on that link and the hesitation caused by the mini-roundabout than any notable conflicting movements. Clearly, this is in contrast to current conditions when no such delay exists.

RFC Q Length Approach Arm AM Peak Sawbridgeworth Road 0.34 1 A1060 Stortford Road North 0.72 2 A1060 Stortford Road East 0.87 6 PM Peak Sawbridgeworth Road 0.42 1 A1060 Stortford Road North 0.53 1 A1060 Stortford Road East 0.70 2 Table 5-2: Proposed A1060 / Sawbridgeworth Road Mini-roundabout Performance

Table 5-2 confirms that the proposed mini-roundabout layout at the A1060 / Sawbridgeworth Road intersection performs satisfactorily in both peak periods. However, there is no perceptible improvement on the existing junction in either peak period.

6 COMMENT AND REVIEW OF CONDITIONS

The results of the mini-roundabout junction assessments suggest that such an arrangement would provide no improvement on the existing road layout in terms of highway capacity. This should not be considered surprising since all arms of a mini-roundabout are forced to give way whereas, under the current priority junction layout, this is not the case.

As the A1060 represents the primary route through Hatfield Heath, it is unlikely that any measure that delays through movements would be advisable. Currently, the only delay for A1060 traffic is at the junction with Sawbridgeworth Road where drivers have to give way to oncoming traffic in the process of turning right. This delay could potentially be removed by making the A1060 the main thoroughfare and reducing Sawbridgeworth Road to the minor route. However, it is possible that such a change could encourage higher speeds in the immediate area. Consequently, as there are no current capacity concerns, it may be preferable to simply retain the existing layout.

It should, nevertheless, be added that the site visit of Wednesday 15th January developed a greater understanding of the peak hour conditions in the whole of Hatfield Heath. It was apparent that, as

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well as the main A1060 flows, there is a large flow of traffic on the B183 from north ( direction) to south (Sheering and Harlow direction) in the morning peak. Conversely, in the evening peak period, there is a notable flow in the opposite direction. This leads to queues of up to 20 pcus on the northbound B183 at the unassessed junction that is just over 100m west of the A1060 / B183 Dunmow Road intersection. If there is a strong desire to improve throughput on the B183, it would be necessary to consider this junction as well as the Dunmow Road junction.

It is possible that this will not be an issue in the long term however. As part of the study into the impact of the proposed Junction 7A of the M11, Highways’ (EH) area-wide modelling has indicated that traffic flows could more than half on the B183 by 2021. It should be stressed that Junction 7A is not yet guaranteed, but if the scheme does come to fruition, concern for any delays in Hatfield Heath will be eased significantly. Furthermore, any rat-running that currently takes place on the south side of the A1060 to avoid queues, for example on Pond Lane, would also be reduced.

7 CONCLUSION

This technical note considers the potential for introducing mini-roundabout arrangements at the A1060 Chelmsford Road / B183 Dunmow Road and the A1060 Stortford Road / Sawbridgeworth Road junctions in Hatfield Heath.

Junction assessments of the proposed arrangements compared to the existing layouts have indicated that there would be no improvement in the performance of the highway network in terms of capacity. Furthermore, mini-roundabouts would delay through trips on the A1060 primary route.

A review of overall conditions in Hatfield Heath has shown that there is a strong demand along the B183 as well as the A1060. This is the reason behind the build-up of queues where the two roads meet. However, in the long term, this may not be a concern as the proposed Junction 7A of the M11 could reduce demand on the B183 notably. An EH study has indicated that flows could fall by more than half in the peak periods and this would ensure that any current delays will be eased significantly in the future.

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APPENDIX A – JUNCTION TURN COUNTS

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B183 Dunmow Rd AM - 0745 to 0845

368 16 164 407 A1060 Stortford Rd A1060 Chelmsford Rd 15 648

B183 Dunmow Rd PM - 1700 to 1800

192 25 354 A1060 Stortford Rd 450 A1060 Chelmsford Rd

26 419 A1060 Chelmsford Road / B183 Dunmow Road (pcus)

A1060 Stortford Rd North AM - 0745 to 0845

1 402 2 189 Sawbridgeworth Rd A1060 Stortford Rd East 395 258

PM - 1700 to 1800 A1060 Stortford Rd North

1 346 1 213 Sawbridgeworth Rd A1060 Stortford Rd East 330 186 A1060 Stortford Road / Sawbridgeworth Road (pcus)

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APPENDIX B – PROPOSED MINI-ROUNDABOUT JUNCTION LAYOUTS

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