Speed Humps
"A speed hump is a raised area of a roadway, which deflects both the wheels and frame of a traversing vehicle. It is longer than the wheelbase of most cars; this feature distinguishes it from a speed bump."
(Source: Canadian Guide to Neighbourhood Traffic Calming)
Many people confuse the term speed hump with speed bump. Vehicles traversing a properly designed speed hump at a reasonable speed i.e. 30 km/hr, can drive with relative ease across the hump. Speed bumps on the other hand, are sometimes installed on private roadways and in commercial parking lots and can be very abrupt and jarring to motorists. Only properly designed speed humps are recognized within the Canadian Guide to Neighbourhood Traffic Calming.
Throughout Canada, speed humps have been installed with success in cities such as but not limited to: Toronto, Ottawa, Pickering, Brantford, Sherbrooke, Halifax, Fredericton, Vancouver, Victoria, Edmonton and Winnepeg. The research clearly demonstrates that the installation of speed humps results in a significant decrease in motor vehicle speeds.
The picture below shows a speed hump in the City of Ottawa that was installed on a local road.
Photograph of a Speed Hump in the City of Ottawa.
The following figures, show cross-sections for properly designed speed humps. There is a recommended design for collector streets and for local streets. The speed hump for the collector street is 80 mm high and 7.0 metres wide at the base and has a flat centre section. This flat section makes it easier for larger vehicle such as buses and fire vehicles to traverse.
Speed Hump Design: Collector Street
(Source: Canadian Guide to Neighbourhood Traffic Calming)
The speed hump design for local roads is also 80 mm high but is only 4.0 metres wide at the base and does not have a flat centre section.
Speed Hump Design: Local Street
(Source: Canadian Guide to Neighbourhood Traffic Calming)
Although speed humps are very effective at reducing vehicle speeds, some potential disbenefits that need to be considered are discussed as follows:
TRAFFIC MAY BE DIVERTED TO PARALLEL STREETS
Before any traffic calming measures are implemented on a street, care must be taken to assess the impact of these measures on adjacent streets. A requirement that the impact on adjacent streets be minimized is strongly recommended. The Canadian Guide to Neighbourhood Traffic Calming states that, "some vehicles may be diverted to parallel streets that do not have traffic calming measures."
The City of Brantford acknowledged that there was a slight shift in vehicle volumes from the City's first traffic calmed street to an adjacent street. One posted turn prohibition seems to have solved this issue and the neighbourhood is very pleased with this traffic calming project that includes speed humps, centre islands and raised crosswalks.
As discussed in the following statement, there have not been serious concerns in the City of Toronto with respect to this issue.
"Staff are careful not to promote this traffic management technique as a method to reduce traffic volumes on a street. To date in the City of Toronto, hundreds of local streets have been traffic calmed. Data on whether traffic volumes are diverted from calmed streets are inconclusive. Some calmed streets have exhibited small increases or decreases (under 10% difference) in daily traffic volumes while others have exhibited relatively higher variations (some more than 20%). This may be attributed to the normal fluctuation of traffic on different days as well as to the different times of year when the traffic was counted."
(Source: City of Toronto)
Engineering Division staff therefore recommend that consideration be provided to all adjacent roadways of any street that is being considered for traffic calming measures. The City should make every effort to ensure that the effect of traffic calming on adjacent streets is minimized.
EMERGENCY SERVICE VEHICLES COULD BE DELAYED
Numerous speed hump studies demonstrate that emergency service vehicles can be delayed by two to ten seconds per speed hump. Although this delay seems insignificant, total delay could be significant if several speed humps are installed along an emergency response route.
"Emergency service delivery is hindered by traffic calming that reduces speeds on regional roads but is relatively unaffected by traffic calming on local streets. Emergency service response times after traffic calming has been put in place, is still within the acceptable time limit as defined by the service provider".
(Source: City of Ottawa)
If traffic calming devices such as speeds humps are to be considered on any street in the City of Kingston, consultation with all emergency service providers would be a key consideration. It is important that the installation of any traffic control device in the City results only in delays to emergency service vehicles that fall within acceptable limits.
INCREASED NOISE FROM VEHICLE DECELERATION AND ACCELERATION
Although traffic noise may be reduced due to lower speeds, there may be increased traffic noise due to vehicles accelerating and decelerating at speed humps. This noise tends to decrease once motorists become accustomed to driving over speed humps. Through extensive speed hump research and discussions with other traffic-calmed municipalities, noise at speed humps does not appear to be a significant issue.
INCREASED MAINTENANCE
On any traffic calmed street, maintenance issues are an important consideration. Most municipalities acknowledge that maintenance/operations staff typically do not support the installation of traffic calming measures. These same municipalities do however believe that traffic-calming related maintenance issues are minimal and can be dealt with in a reasonable fashion. For example, during the winter months, the snowplow blade can be lifted when clearing speed humps. As the location of each speed hump is carefully signed, operators know where to lift the plow blade. The snow clearing time on streets with speed humps may therefore be slightly increased. As speed humps are designed with a gap at the curb, drainage is facilitated and summer maintenance issues are usually not a concern.
To gain support for traffic calming, the City of Ottawa provides a small amount of additional funding within the maintenance budget to account for extra work that could be required on traffic calmed streets.
Despite the above-noted disbenefits that must be considered, all of these concerns have been reasonably addressed in other traffic-calmed municipalities. Speed humps have been so effective at reducing speeds that in the opinion of City of Toronto staff, "judging from the popularity of physical traffic calming measures throughout the world, the general public seems to be generally in favour of the benefits over the disbenefits. Furthermore, the use of traffic calming has been acknowledged by the Transportation Association of Canada and the Institute of Transportation Engineers. "
The cost to construct and install a speed hump varies according to the width of the roadway and typically ranges from $2000 to $5000 per speed hump. The City of Toronto estimates the average annual maintenance cost for marking and signing to be less than $100 per speed hump. Snow removal costs are negligible.
