Aerial view

Walmer Boulevard at M4

Detailed description


In this proposal the traffic signals are decommissioned and the T junction assumes the shape of a flattened traffic circle, about 500 meters long. On the northern side a half circle is created through a vacant parking area below the elevated M4. On the southern side a half circle is built on vacant land adjoining the narrow gauge railway terminus. Traffic lanes are rearranged to create a continuous flow pattern and waiting at traffic signals is eliminated

Traffic from Walmer point 1 approaches the T junction. The Traffic signal at point 2 has been removed and a barrier rail (25) prevents a right turn towards Summerstrand. All traffic at point 2 therefore turns left. (the left in left out principle.)

Traffic past point 2 splits. North bound traffic bears right onto the M4. Summerstrand and CBD traffic bears left towards point 5.

At point 5 CBD traffic proceeds past point 7. Also at point 5 Summerstrand traffic turns right and passes under the M4 bridge, through a mostly vacant parking area, emerging at point 6 to join CBD traffic from point 8 at point 9. This is the first half key to the proposed continuous flow interchange (CFI)

At point 9 the existing 4 lane forms a jug handle leading to the existing M4 signalised intersection. It is proposed to straighten the jug handle by building a new parallel section to join the South bound M4 between points 10 and 11 resulting in a continuous flow merging section. After this section is built the existing 4 lane from 26 to 27 will become disused.

Beyond point 11 on the East side of Humewood Road lies a patch of vacant ground on which a large half circle (14) can be built, which is the other half key to the proposed continuous flow interchange (CFI)

From 11 to 12 an approx 200m weaving section will exist. At 12 South bound Summerstrand traffic (12 to 15) will separate from West bound Walmer traffic. Walmer traffic will round the half circle clockwise and merge with Northbound traffic from Summerstrand at 16. Between 16 and 18 traffic will weave in a 200m section and West bound Walmer will exit to the left.

Continuous flow at Walmer M4 will shift the bottle neck to the Perrot street signal and then to the Driftsands exit, so these should also be made left in left out intersections. In the case of Perrot street a center barrier, in out lanes (21 and 22) and removal of the traffic lights will clear that intersection . For Perrot street wishing to go South, a small circle 28 can be placed alongside 14.

For Driftsands a half circle can be built partway up the hill to allow adeqquate lane length for weaving by Beach Road traffic wishing to go North on Humewood Road

At 3 a short weaving section for cross flow of Walmer traffic to the M4 and Summerstrand traffic to the CBD, occurs. This crossflow has relatively low demand and the short weaving section could be adequate. In the long term when traffic increases the stub ramp at 29 can be introduced after which weaving capacity will be sufficiently increased.
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