Coolaroo/Dalrymple Speed Humps

CoolarooHumpsOn 7 September 2015 Council resolved to adopt most of the recommendations of the Mowbray Road West Traffic Study.

This study was carried out by consultants PeopleTrans on behalf of Council.

One of the recommendations approved by Council was for the introduction of traffic calming measures in the form of a Local Area Traffic Management in Coolaroo Road and Dalrymple Avenue. It was noted within the Council resolution that the design of the LATM Scheme “will require considerable resident consultation, and there will be considerable cost involved to construct the devices”.

The PeopleTrans Study found that Coolaroo Road and Dalrymple Avenue are key routes for locals, but are also used as rat-runs by other drivers to avoid congestion on Mowbray Road West during the morning peak period.

In September 2015 PeopleTrans were commissioned by Council to undertake the concept design of the LATM measures on Coolaroo Road and Dalrymple Avenue. These measures were aimed at addressing the concerns of local residents regarding safety by reducing speed and aggressive driver behaviour on those roads.

On 19 November 2015 PeopleTrans conducted a workshop which was attended by two residents from Coolaroo Road and two residents from Dalrymple Avenue, as well as Council officers. The primary outcome of the workshop was to reach agreement on what the LATM scheme should achieve, and the location and type of LATM devices that should be introduced. At the meeting it was agreed that there were two main types of treatment that would be appropriate for Coolaroo Road and Dalrymple Avenue. These treatments were:

 Sinusoidal road humps

 One lane slow points

It was recommended that these devices need to be located such that they are not too far apart, (approx. 80m) if they are to be effective in reducing speeds along the whole street. Also, different types of devices may have varying impacts when used in combination. A sinusoidal road hump differs from a watts profile speed hump in that it has a smoother curved profile at its base where it meets the road. Therefore it is less severe when vehicles drive over it. For the one way slow points the study recommended that Give Way signs be installed so that right of way be given to traffic in one direction over the other direction. This is intended to reduce conflict issues related to right of way and improve the overall safety of the devices.For both sections of Coolaroo Road, this would mean that eastbound traffic would be required to give way to westbound traffic at the slow points. On Dalrymple Avenue northbound traffic would be required to give way to southbound traffic.

The advantages and disadvantages of the sinusoidal road humps are listed below:

 Effective in reducing speeds

 No loss of parking as drivers will be allowed to park their car on the road hump

 Sinusoidal hump has a preferred profile for cyclists compared to watts profile or flattop

 Would be cheaper to construct than one lane slow points

 Some increase in noise due to vehicles driving over the device, but anticipated to be within acceptable levels

The advantages and disadvantages of the one lane slow points are also listed below:

 Effective in reducing speeds

 Includes a bicycle bypass lane

 No increase in noise

 Some loss of on-street parking (11 spaces in Coolaroo Rd west, 9 in Coolaroo Rd east, 8 in Dalrymple Ave) T

here was also a 3rd option for the section of Coolaroo Road to the west of Greenlands Road. This option involved a combination of formalised parking spaces and road narrowing. However this option would result in the loss of 53 out of 76 available on-street parking spaces in this section of Coolaroo Road, so it was not considered acceptable.

In addition to the above devices, PeopleTrans also recommended a modified T-intersection where Coolaroo Road meets Dalrymple Avenue.

The PeopleTrans report found that the LATM options provided for Coolaroo Road and Dalrymple Avenue would achieve the key objective of reducing speed to below 40km/hr and improving resident amenity in these streets. It also found that the relative difference relating to speed reduction between the road humps and the slow points was marginal. The slow points would be better from aesthetic viewpoint, due to the opportunity for landscaping and the minimal noise impacts, however this needs to be weighed up against the loss of parking for this option.


That Council consult with residents for their views on the proposed introduction of;

1. Sinusoidal speed humps, or

2. One lane slow points, to determine a preferred option for traffic calming devices in Coolaroo Road and Dalrymple Avenue.


5 thoughts on “Coolaroo/Dalrymple Speed Humps

  1. Please let me comment on some items from the latest newsletter.

    Coolaroo/Dalrymple Traffic Calming

    Rather than giving us chapter and verse on the possible treatments, where is the Council’s brief to People Trans? Presumably there have been some accidents/incidents/complaints from locals and /or rat runners to warrant even more traffic calming in this area. Even after all the house renovation in Coolaroo has decreased, there is still virtually all day and night parking on both sides thereby effectively creating a single lane road. Why must it be formalised?

    Council and People Trans seem determined to provide ever decreasing levels of service to west Chatswood residents. Evidence includes the Lane Cove traffic lights at Mowbray/Beaconsfield as they remain a continuing hindrance to Beaconsfield users, the 15 kph hump in Centennial making three humps in 200m, more lights proposed for Mowbray and little relief from all day parking along the 255 Bus Route particularly in Dalrymple north (where there are 2 nature strips each 5 m wide) and Beaconsfield.

  2. We are NOT in favour of the speed humps being placed as suggested in the article.
    This is the first we have heard of all this and it would affect our quality of living as the placement on Dalrymple Ave of one of the speed humps is less than 3 metres from our main sleeping and living area.
    We happen to be one of the houses with streets both front and rear of our properties.
    It is bad enough hearing the constant passing traffic and to add to that cars constantly going over a speed hump would send us crazy!

    When and who can we see to discuss these issues?

  3. From a resident remote from the subject areaL

    In response to the article on the back page of West Ward News re Traffic “CALMING” in Coolaroo Road, with the continuous single lane curves in the road speed in general would be well below average and not an issue. start by observing UBD map 195, the roads are a series of connecting streets all depending on each other for the thousands of people ( motorists ) that live in your area, it is possible that up to seventy five per cent of the traffic using Coolaroo Rd are from their local neighbourhood.

    Coolaroo Rd is a three lane road often parked out with vehicles on both sides leaving only one through lane to connect to the safest way, the only way, to the traffic lights on Mowbray Rd. It is obvious that the consultants option for Speed Humps is a very costly burden on Willoughby rate payers and it would be an absolute waste of money and Will Not stop traffic using Coolaroo, nor should it, we all have a right to share and to use all streets we need to, to get to our destination.
    To the residents who think they have a monopoly on Coolaroo Rd. – rather than waste our council rates, dig a series of pot-holes along the length of the road in question, ( we pay council to fill pot holes then we pay them to build humps ) you can dig and own them and they will cost nothing that we “outsiders” will have to pay for, and, they will have the same effect as the so called “Traffic CALMING” effect as claimed for the Speed Humps that the consultants suggest. The benefit to the hard done by residents is that not one single parking space will be lost.
    The other alternative for the complaining residents is close Coolaroo Rd from exiting into Greenlands Rd. That would be a fair option for every one, well “only a thought” yes it would be a bit over the top.

    The money saved on Speed Humps in Coolaroo would be better spent changing the existing Speed Humps in those streets throughout the area to allow for two for way traffic. What is “calming” when you havie to keep stopping to allow for opposite traffic to come through when you could have passed side by side over the same hump.
    When I was a member of the West Ward traffic committee I made it a point to not only listen round a table to claims being made of a traffic problem affecting some’ones area, but to go and spend the time needed to see ift it was a valid claim being made and what if possible could be done without compromising someone else’s situation. .

  4. Edited reply from a local resident:

    With respect, this is ridiculous. A philosophical opposition to traffic calming?? Once you get past all the sneering about our legitimate safety concerns, he is actually advocating traffic aggression and taking the position that our kids’ lives should be put in even more danger, as long as his convenience is intact and he doesn’t have to pay for it.

    My kids’ lives DO matter, and I don’t care how many years of input he has had in this issue—the problem is getting worse every day. Looks like he hasn’t made a hill of beans worth of difference.

    Nice to know that we have neighbours who are so selfish and callous about safety issues.

  5. From a local resident:

    Further to my last email, I should point out that the Coolaroo residents have given up on trying to steer traffic away from our street—at this point, there is no safe alternative, and no one in a position of power seems to give a rip about it. However, I don’t think it’s too much to ask that the traffic which is forced down Coolaroo, most of it local traffic, should be traveling at a safe speed. If we could count on our neighbours in the west ward to drive down our road safely, it would not be an issue, but we all have experienced that we can’t. To me, it is pouring salt in the wound to insist on a God-given right not only to turn our street into a motorway slip road but also to do so aggressively.

    I don’t accept that. We can do better.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s