Traffic calming
Traffic calming refers to measures used to attempt to improve the safety or use of roads. This is by either reducing the volume of traffic or reducing the speed of traffic on the road.
Traffic calming measures are mostly used on two types of streets. These are residential streets and streets with high numbers of vulnerable road users. For example, school children or elderly pedestrians.
There are three main categories of traffic calming measures:
- Education: bringing speeding issues to the community's attention. Typically occurs on a statewide basis and comes from the Tasmanian Government.
- Enforcement: the punishment of inappropriate behaviour as a deterrent. Enforcement is the responsibility of Tasmania Police.
- Engineering treatments: physical alterations to the road environment. The aim is to encourage drivers to change their behaviour. Engineering treatments on local roads are generally initiated by the City of Hobart.
Engineering treatments
The two types of treatments are intersection and mid-block.
Intersection treatments
Traffic calming measures at intersections include:.
- roundabouts
- traffic signals
- traffic islands
- banning turning movements.
The most effective way to slow down speeding vehicles is to install a roundabout. Drivers on every approach to a roundabout have to slow down enough to give way to other traffic.
Mid-block treatments
There are three classes of device used in a mid-block location to reduce vehicle speeds. They are:
- vertical displacement devices (such as road humps)
- horizontal displacement devices (such as chicanes)
- road narrowing treatment (such as kerb outstands or the installation of median treatments).
Vertical displacement devices rely on discomfort to the driver caused by driving up then down so they have to reduce their speed. Road humps reduce vehicle speeds, but can also:
- reduce on-street parking
- increase vehicle noise through heavy braking and accelerating
- increase reaction times for emergency vehicles.
A horizontal displacement device slows vehicles by forcing them to drive side to side. These devices tend to work well on residential streets that do not have to cater for large trucks or buses.
A treatment to narrow the width of the road can also reduce traffic speed. Roads can be narrowed by:
- on-street parking
- planting trees
- linemarking
- the installation of median treatments.
All the above mid-block treatments have certain advantages and disadvantages.
Traffic calming measures in mid-block locations focus the reduction of vehicle speeds. All devices are designed and installed to the approval of the Tasmanian Government.
Other mid-block options
Traffic calming can also be achieved by more severe methods. This includes:
- closing access to a residential street from one end (turning the street into a cul-de-sac)
- turning a road into a one-way street.
While these treatments can be very effective, they also can be very divisive. They may transfer problems to other nearby streets, and need strong justification to put in place.
Issues with traffic calming
Traffic calming has the potential to provoke strong feelings in the community. Treatments that restrict access or present obstacles are sources of controversy. For example, making streets one way, or road humps.
One of the most effective and least controversial methods is roundabouts at intersections.
In mid-block locations, the least controversial measure is the installation of median treatments. Unfortunately residential streets are often already narrow, and some measures aren't possible.
The City of Hobart has a limited amount of funds available for capital and maintenance works. This makes speed humps the main speed reduction measure due to being cost effective. The speed cushion using recycled rubber is by far the most effective treatment.