R132 Swords: Estuary junction, what we saw and what could help

The following are observations only and should be properly measured by a suitably qualified Traffic Engineer.

Executive Summary

The newly opened Estuary junction was observed to have two significant functional problems.

1. HGV turning restriction from the R125 Balheary Road West onto the northbound R132.
2. Right turn queue from the northbound R132 onto Balheary Road West.

1. HGV turning restriction, R125 Balheary Road to northbound R132

The turning geometry was observed to be too tight for HGVs approaching from the R125 Balheary Road from the west to complete the right turn onto the northbound R132 normally.

On a green signal, with the R132 on their left, HGVs must crawl towards the central island and then swing sharply left to obtain sufficient rear wheel clearance before completing the turn.

This necessary manoeuvre blocks following traffic and prevents left turning vehicles from moving until the HGV has cleared the junction.

This is not a temporary construction issue

The problem was initially assumed to arise because the junction was unfinished, with the expectation that the remaining curved sections of the former roundabout might become slip roads. The published designs show that this is not the case.

2020 consultation schematic: Public Consultation Document, page 16. Reference: Figure 6.1, Estuary Junction Emerging Preferred Option

Later planning drawing: R132CP Planning Drawings, page 9. Reference: Drawing 200021-DBFL-RD-SP-DR-C-1107

The restriction therefore appears to be part of the permanent junction design.

Temporary mitigation possible solutions

A temporary slip road could be formed using traffic cones along the remaining outer curve of the former roundabout. Left turning traffic from the R125 could use this temporary lane to join the northbound R132 separately from the main junction movement.

This would remove left turning cars from the road space currently required by HGVs and allow HGVs to make the right turn more naturally.

The simplest emergency arrangement would be a temporary stop sign at the end of the slip. Vehicles would stop and enter the R132 when the normal junction signal sequence creates a safe gap.

If observation showed that the stop controlled arrangement was insufficient, a temporary signal connected to the existing junction sequence would be the next option.

2. Right turn queue from the R132 north approach onto Balheary Road West

The dedicated right turn lane cannot accommodate the observed demand and the signal phase does not reliably clear the queue. Once the lane fills, waiting traffic backs into the main R132 lanes and reduces through capacity for Right and through traffic causing a tailback.

During the field observation, approximately 20 vehicles cleared during one right turn phase, yet the demand was sufficient for the turning queue to build again shortly afterwards.

Signal timing should be calibrated against live observed demand, with the objective of clearing the turning queue before it repeatedly spills back into the R132 through lanes.