5. TOTAL NORTH BOUND
TOTAL SOUTH BOUND
TOTAL EAST BOUND
TOTAL WEST BOUND
SEAFORDROAD
(WEST)
SEAFORDROAD
(EAST)
Green Shaded
Dedicated crossing points
Salmon Shaded
Within 50m of the roundabout
27
1
1
57
0
0
62
33
41
PEDESTRAIN MOVEMENTS
3 7
17 12
13 20
42
GRAND BOULEVARD
NORTH
29
19
0 2
GRAND BOULEVARD
SOUTH
9. Crashes –
• Engaged GTA consultants to investigate crashes and identify
solution.
• Based on casualty crash numbers over a 5 year period the
intersection was eligible to be nominated for Black Spot
funding.
High entry speeds –
• GTA to address vehicle speeds as part of the Black Spot
nomination.
• Investigate options to reduce vehicle speeds on the approach
to the roundabout
Delays–
• GTA to undertake SIDRA modelling to capture existing traffic
conditions and model proposed treatment to ensure LOS
does not drop
10.
11. Pedestrians still a concern–
• Liaised with DPTI in regard to non-standard treatments.
• Liaised with Jeremy Wooley from CASR in regard to adapting
a safe system approach
Introduction
Name – Traffic Engineer, City of Onkaparinga
Subject
So called title Seaford Roundabout!
Location
City of Onkaparinga
Located over the hill
Road functions
Seaford Road is classified as a Distributor road providing connectivity between Seaford, Port Noarlunga and Moana to Main South Road and Southern expressway
Grand Boulevard is a Collector road between Seaford Rise and Seaford Meadows
Vehicle movements
Seaford Road accommodates approx. 13,000 vehicle movements per day
Grand Boulevard has approx. 5,000 vpd with a high number turning onto Seaford Road (east to travel to MSR)
1,300 right turns from south and 1,600 from north to Seaford Road east
Issues
Complaints over a number of years
Speeding vehicles cutting lanes
Poor sight lines on northeast corner
Retirement village and school to the south – crossing 4 lanes of traffic
Doctors surgery, Dr Jones and residential north of the roundabout
Roundabout are good to reduce injury crashes not ped friendly
Pedestrian Movements
HDS to undertake a 12 hour traffic survey
Total of 193 crossing movements
Main crossing movements between north and south 71 between the doctors and retirement village
48 between schools and residential
Not high compared to a lot of high pedestrian locations but has large number of vulnerable uses
Current queue lengths and delays
Worst case scenarios
Southern leg Grand Boulevard related to school pick and drop off between 3pm for about 15mins accommodating 320 vehicles per hour
Crash history
DPTI crash map
Total 13 crashes over a 5 year period 2012-2016 inclusive
8 resulting in injury
Rear end hitting stationary vehicle and angled crashes
Concerns
Vulnerable pedestrians elderly and children crossing Seaford Road
Number of crashes 13 over five years
High entry speeds cars often cut between the lanes to maintain high speeds upto 50km/h
Delays though not an issue generally worth capturing to ensure they are not extended over a longer period
Investigations and solutions
Crashes – We engaged GTA consultants to review the crashes particularly right angle crashes, improve sight lines and reduce entry and departure speeds.
Create a concept design
Bring forward the give way lines to improve sight lines
Dedicated right turn lanes
Extend centre median
Required to accommodate 19m semi and buses
Provide single exit lanes and through lanes to Seaford Road
LOS hardly changed
No pedestrian related crashes
Submitted for federal Black Spot funding
Agreed to install wombats on all approaches to create consistent approach and exit speeds on all legs
DPTI agreed to wombats within 60km/h road
Adapting safe system approach
Originally had 2 Wombats but Jeremy suggested all legs to get consistent speeds
Extended the centre annulus approx 2m each side to made it an egg-about – Natural movement
Banned right out movement from GP Axis
Short right turn lanes to accommodate crossing – Modelling shows it works
Offset crossings to prevent pedestrians cutting straight through and reduced traffic delays
Provided width for 2 gophers to pass each other
Install 40km/h speed limit speed limit within roundabout
Keyed in islands with reseal
Back to back kerb considered between lanes
Original black spot estimate $70,000 for 100% funding.
Detailed estimate with 4 wombat crossings $368,000 mainly lighting and stormwater
Project wasn’t funded so will have to undertake a staged approach
DPTI increased black spot funding to $105,000
Final cost $127k by sub contracting work out
Reduced design to sit on concrete and rubble in fill to reduce costs
Management wanted to use paint on the centre annulus to further reduce costs
Flush cut through
Wombats not installed but can be retrofitted at a later date
Large catchment area
Installed banners on all approaches
Met with retirement village, doctors and adjacent residents
Put information on web site
More educate how it will work than consult – Already know the issues
Held open day at Seaford shopping centre where we discussed the treatment and played a fly through video
Online trolls all put there opinion forward, some had alternative suggestions which included demolishing the medical centre and retirement village
Many didn’t want to be slowed down
This fly through was created in house by one our designers Infraworks, 3D studio max and Civil 3D
REVIEW
Used Thermo-plastic line marking should last 5 years
Cars cutting painted median
Pedestrian number have increased slightly, Though not all use the crossing area, many following the desire lines
Will be interesting to get the crash data though haven’t heard of any yet
Appears to be operating well
And that completes my presentation………..