SIDEWALK TECHNICAL DESIGN GUIDELINES
Introduction
Sidewalks are an integral part of roadways. They play a significant safety role in separating pedestrian activities from vehicular traffic.
A sidewalk network should provide convenient access to the outdoor environment for all people in our City.
These Guidelines are in accordance with the Regional Road Corridor Design Guidelines dated July 2000 and Transportation Association of Canada (TAC) Urban Supplement to the Geometric Design Guide for Canadian Roads.
History
Providing a safe walking surface for pedestrians at driveways, while at the same time providing vehicular access to homes and businesses, has been a concern of the City’s since the 1950’s with the result that several improvements to our sidewalk standards have been made.
● Prior to the 1950’s, asphalt or concrete ramps projected out from the edge of the sidewalk onto the roadway which resulted in drainage problems along the sidewalk, and serious difficulties for maintenance vehicles such as snow plows, sweepers and flushers. Outside ramps at driveway entrances are now prohibited in Ottawa.
● Between the mid 1950’s and 1970’s, the sidewalk at the driveway had a substantial slope or cross-fall from back to front of the sidewalk to accommodate vehicular access.
● In 1970, specifications were changed to lower the back of the sidewalk to reduce the cross-fall of the sidewalk at the driveway.
● In 1973, further changes increased the length of the tapered slope section approaching the driveway in the pedestrian’s direction of travel along the sidewalk, to further reduce the slope in the direction of travel. In some locations, however, site constraints prevent strict adherence to the new design standards.
● In 1975, ramping curbs at intersections and pedestrians crosswalks to facilitate the use of City sidewalks by persons confined to wheelchairs.
● In 1990, the surface finish of the pedestrian ramps were “roughened” to alert visually impaired people that they were about to cross a street or have reached the other side of the street.
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● In 1992, a slight variation in sidewalk design consisting of an integral mountable curb and sidewalk was reviewed. The merit of this design is that it eliminates the “wavy or undulating effect” to the sidewalk at the driveways and provides a level walking surface for pedestrians. Some of the disadvantages of sidewalks with mountable curbs are that they provide less protection for pedestrians than the full barrier curbs and secondly, they permit vehicles to easily park on the sidewalk thereby interfering with safe pedestrian movement along the sidewalk and hampering snow clearing operations. This parking problem currently occurs city-wide in areas where the curb face at the sidewalk has been reduced due to road overlay works undertaken prior to the advent of grinding operations. In addition, there are maintenance disadvantages with mountable curbs regarding street flushing, street sweeping and snow clearing operations along the gutterline that are greatly reduced with full barrier curbs.
However, the main reason for not using sidewalks with mountable curbs is parking control. The City of Ottawa is a city that wants to prohibit illegal access/driveways and illegal front yard parking city-wide. This is accomplished through zoning rules and regulations, the private approach by-law and the use of full barrier curbs. The lowering of the height of the barrier curb (depressed access) to permit vehicular access and parking on residential and commercial properties is permitted only at locations deemed legal by the zoning regulations and private approach by-law. No doubt, in spite of all our efforts, there are still some illegal access and front yard parking occurring city-wide. If the City switched to sidewalks with mountable curbs, the passive portion of parking control would cease to exist and we would anticipate an increase in front yard parking problems.
For these reasons mountable curb are not recommended and generally not adopted.
Location
To determine the location
and/or need of sidewalks, many factors, such as the following, must be taken
into consideration,
● vehicle
speed
● traffic
volumes
● truck
volumes
● public
transit volumes
● school
bus volumes
● total
pedestrian volumes
● handicapped
and elderly pedestrian volumes
● children
pedestrian volumes
● elimination
of a school crossing
● direct
routing to schools-parks-shops-churches-recreation centers
● accident
experience
● parking
occupancy
● shoulder
width
● type
of shoulder
● presence
of curb
● adequate
lighting
● abutting land
use
● extension of
existing sidewalk
● existing sidewalk on the other side of the street 2
From a purely safety point of view, sidewalks should be required on both sides of every street, however for the sake of economy this is not standard practice. It is recommended that sidewalks be provided on both sides of Arterial Roads, Major Collector Streets, and on one side of Minor Collector Streets and Local Streets where the Right of Way width is atleast 20 m. Sidewalks are not recommended on minor local streets where the Right of Way width is less than 20 m such as Crescents, Cul-de-sac, etc., unless they form a well defined route to activity centres such as schools, recreational centres, senior residents etc.
The location of the sidewalk on the road allowance is also subject to a number of variables generally relating to the expected use of the street, the width of the road allowance and historical community acceptance. In the older neighbourhoods and downtown areas of the City, sidewalks were generally built immediately adjacent to the curbs (see drawings No. SC2, SC3, SC5, SC6, SC8 and SC103). While this type of construction provided good access for people getting in and out of their cars and longer landscaped areas in front of the homes, it minimizes the pedestrian separation from vehicular movement on the street.
Where possible, in residential areas and other areas where Zoning By-Laws provide adequate provision for building set back from property lines, sidewalks should be constructed with a minimum distance of 1.5m (2.0m preferred) from the back of curb and 1.0m from the property line (see drawings No. SW1, SC4, SC7 and SC104). If the minimum 1.5m separation cannot be achieved, a smaller separation would be acceptable provided the separation area is a hard surface area such as asphalt, concrete or interlocking bricks. The specific location, depends of course, on the right-of-way width and pavement width, which provides the following advantages:
(a) A boulevard width between the sidewalk and curb adequately sized to provide a degree of safety between vehicular and pedestrian movement.
(b) Boulevard provides space suitable for landscaping and possible tree planting generally making the street more aesthetically pleasing.
(c ) Boulevards would allow driveways to be sloped between the curb and sidewalks, thereby eliminating the need to drop the sidewalk to allow vehicular access to the driveway. Sidewalks could then be built flat.
(d) Boulevard protect pedestrians from being splashed by vehicles.
(e) Provides space both on the property side of the sidewalk and in the boulevard to enable the installation of some of the underground utilities rather than under the paved road surface which eases the construction and maintenance of the utility.
(f) Boulevard provides space for snow storage which can greatly reduce snow removal costs in areas so affected.
(g) Boulevards also contributes micro-climate and environmental benefits.
Boulevards provide space for various street hardware such as signs, lighting poles, transit shelters, hydrants etc.
Alignment
Sidewalks with boulevards can be adjusted from their normal alignment paralleling the property line or road curb to avoid healthy mature trees, hydro poles, or other surface topography which are felt desirable to preserve.
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The bends in the sidewalk in these locations should be smooth; long enough to provide for the movement of sidewalk snow clearing equipment within the sidewalk width.
For the same reason it is also desirable that the sidewalk have a minimum 0.5 m lateral set-back for trees, light and sign posts, etc. This clearance also assists pedestrian flow along the walk, and is of particular assistance to blind people.
Width
Whenever feasible and practical, the designer should attempt to provide a 1.8 m sidewalk. This width provides for safe passing room between an adult and a person pushing a baby carriage, a person in a wheelchair, child on tricycle, etc. (refer to following "Dimensions for People Outdoors"). However, if there is any physical constraints such as poles, retaining walls, rock gardens, fences, hedges, trees, etc..., a 1.5 m sidewalk would be acceptable.
To clear the snow off the sidewalks, the 1.5 m minimum width reduces the potential of damaging adjacent landscaped areas by the snow clearing equipment.
In general, the intensity of land development measured in terms of people per unit area require a sidewalk of higher capacity. Extra width sidewalks of 2.0 and 2.4 m should be provided near schools, hospitals, offices, commercial and industrial areas where large pedestrian volumes occur. In shopping areas and entertainment areas even wider widths of 2.4 to 3.6 m should be considered. Also for arterial or major Collectors where the right of way width is 26 m or greater, the sidewalks width should be 2.0 m.
Accessibility
for Various Sidewalk Users
The designer must keep in mind that sidewalks are not only for regular pedestrian but for many different types of users such as people with children, packages, strollers, wagons, canes, crutches, dogs or wheelchairs.
All sidewalks must be designed to allow all the above users to have free unobstructive access and feel secure when using the sidewalks.
These needs are most acute at intersections where pedestrian and vehicular paths must cross each other. Intersection accessibility refers to the comfort, security and safety provided to pedestrians during all activities involved in crossing an intersection. Frail elderly persons and persons with disabilities constitute a segment of the population with a broad range of conditions which may hinder mobility. This population includes the elderly who may no longer by fully mobile, as well as people who have a physical disability which impairs their movement or ability to readily interpret the situation at an intersection. Additionally, this group may include people whose mobility is restricted because they are pushing a stroller, carrying a parcel, etc.
Therefore, pedestrian crossings are the areas were the designer should be most concern when designing sidewalks.
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Gradient
The recommended cross slope for sidewalks is 2%. The cross slope may be increased at driveways, but it is recommended that it be no greater than 4%, due to the increased slipping hazard. With the introduction of boulevards, the cross slope of a sidewalk at driveways may be maintained at the desired cross slope of 2% by using the boulevard to adjust any grade difference between the road and driveway. These cross slopes should be achievable in all new developments and subdivisions. However, in existing developed areas where physical constraints may prevent the implementation of these cross slope limits, an absolute maximum cross slope of 6% may be considered for very short sections and preferably only on low volume usage sidewalks.
Generally, the sidewalks will follow the road gradient, with the maximum sidewalk grade controlled accordingly.
When the sidewalk longitudinal gradient is in excess of 6% but less than 8% due to the road grade it should be generally considered as a ramp and may require a coarser surface texture as an aid against slipping during icy weather. If longitudinal grades are greater than 8% alternative solutions such as the use of handrails should be considered.
Drainage
Experience in our northern climate has shown that a cross slope of 2% is desirable to provide reasonable drainage off the sidewalk during freezing weather. An absolute minimum cross fall of 1% should only be considered for short sections of walk where particular design conditions may warrant its use. Particular care must be made in the design and installation of a sidewalk to ensure that drainage from the private properties onto the road allowance is not blocked.
Where the drainage from a large lot or from several small lots is carried down a swale to the road, it is desirable to intercept this drainage by means of a catch basin or a culvert at the back of the sidewalk. Drainage of this nature, particularly from larger areas, may cause winter icing problems if allowed to drain over the sidewalk.
Normally where the drainage is of a local nature, the sidewalk grade should be adjusted to allow the drainage to pass over it.
Care should also be taken to ensure an adequate boulevard cross slope, so that the drainage may be carried clear off the sidewalk and over the road curb. A minimum overall boulevard slope of 2% should be maintained for this purpose. The designer should attempt to intercept the surface drainage in shallow swales between the curb and sidewalk in order to clean and reduce the amount of storm water getting to the catch basins on the street (see drawing No. SW2).
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Surfaces and Construction
Sidewalks should always be constructed in concrete because concrete has proven to provide a long life with generally low maintenance, together with a pleasing walking surface.
Asphalt can be used as a temporary repair of an existing sidewalk or for pathways.
Interlocking bricks are sometimes used in commercial areas or public facilities to gain the benefit of their decorative values. However, the installation and maintenance cost of interlocking brick are normally higher than concrete. Therefore, interlocking pavers should be limited to other walking surfaces such as hard surface boulevards, pedestrian nodes such as super mailbox station areas, transit stops etc…
Attached are several drawings providing typical details for the installation of concrete sidewalks.
It is recommended that asphalt walks be constructed, using a minimum asphalt depth of 50 mm HL3A over a minimum of 150 mm of Granular 'A' material.
Interlocking brick walks are also placed on a granular base and the installation should follow the manufacturer's specifications and recommendations. (see drawing R3).
Particular attention should be made to the construction of pedestrian ramps between the sidewalk and the road surface on curbed streets. The details are shown on the attached detail drawings.
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APPENDICES
Protect
healthy mature trees. Hydrant
to be relocated to provide min. 0.5 m clearance from swk Property
owner requested to relocate fence and plantings clear of road allowance. Hydro
relocate guywires to be clear of sidewalk. If
drainage swale low or flow from several properties or large area, install
suitable dia. pipe (min. 450 mm dia.) Where
possible, saw cut existing concrete or asphalt driveways to match with
sidewalk. Normal
and min. 2% crossfall, unless there are special circumstances. Existing
driveways to be reconstructed as necessary to provide suitable gradient for
drainage and vehicle operation. The
sidewalk elevation is related to existing curb elevation or anticipated
future curb elevation, thereby, providing suitable drainage as required
from the private properties, across the sidewalk, and across the boulevard
to the curb or ditch. Small
trees or shrubs may be transplanted as part of construction or by others
prior to work subject to time of year. 8%
max. recommended for driveways where road has normal cross fall. Maximum
slope in embankment or cut should be 3:1. In
special circumstances a boulevard swale may be used with drainage to a
catchbasin or out to the road at a driveway.
Document 2
Comments from the Accessibility Advisory Committee
The Accessibility Advisory Committee provided the following comments. The Department’s response follows each comment.
- Personal anecdote, from a committee member who lives near the Civic Hospital, about current sidewalk designs, such as those on ParkdaleAvenue. As a person who is ambulatory but not the steadiest on my feet, I fear for my life when the walks are iced (as they often are) and a bus is flying by. If one slipped on the sloped surface of a driveway, one would instantly be under a fast moving bus whose motion has a vacuum cleaner (venturi) effect of pulling objects into it. And much of the Parkdale Avenue sidewalk is low rise similar to mountable curb design. I do appreciate the extra energy requirements placed on wheelchair users if the slopes were instead kept horizontal, i.e., dipping down for every driveway.
Response
These deficiencies will be addressed either through regular maintenance such as road resurfacing, snow removal, etc… or when the sidewalk is reconstructed on Parkdale Avenue.
2. Has any consideration been given to using pavers to contour the Pedestrian Curb ramp? This would serve two purposes:
a) It would provide a colour and texture contrast indication for blind and vision- impaired pedestrians.
b) It would allow easy maintenance to regulate height of curb lip after regrading of street surfaces, and to repair damage due to frost heave.
Response
a) The colour needs to be bright such as yellow or orange and pavers are usually dark red. The Department is currently experimenting with the painting of some pedestrian curbs yellow to evaluate its resilience, functionality and practicality.
b) The curb portion cannot be adjusted independently from the road and sidewalk elevation. The sidewalk adjacent to the pavers would need to be adjusted as well. As well, pavers will move over time and create some unevenness.
- Although expansion joints are specified to be 10 mm with the pre-molded fibre-board, the concrete is finished with a round-over or level that results in a gap of at least 20mm, as shown in your expansion joint profile. Wheelchair users suffer greatly when constantly running over these gaps. They are hard on the back especially. Can the bevel be eliminated so that the gap is at a minimum?
Response
The expansion material (premoulded fibreboard) is usually flush with the surface of the sidewalk thereby minimizing any bumps. Notwithstanding, that the fibreboard will deteriorate over time and create these gaps, the Department has yet to uncover an economical alternative to using fibreboard.
4. There should be a specification for curbs at city parks and recreational facilities that would allow a curb cut where no sidewalks exist. A curb makes it awkward for wheelchair users to gain access without having to make a long detour.
Response
Agree. If the Committee could provide a list of Community Parks that are not accessible, it would be passed onto the appropriate Department for action.
5. There should be a
specification to allow for increasing the existing sidewalk grade level to
allow for easy access to premises abutting the sidewalk, especially when the
complete front of the stores are accessed by one or two steps and access
barriers can be eliminated by raising the whole sidewalk. Of course, a solution would be required at
the curb so that there is an easy transition from street to sidewalk.
Response
This was done on Sparks Street Mall where no road exists or vehicles allowed. On a normal street, this would be extremely difficult to do without creating hazardous situations for the sidewalk users.
6. A specification should be added to ensure pavers are flat so that no edges protrude. This is a serious tripping hazard if an edge lifts even 5 mm.
Response
This is more of maintenance issue. The standards do include requirements to ensure that paver installations are flush, but over time differential movement may cause the pavers to move. When this occurs, maintenance is required to correct.
7. Going into the guidelines presented to us by the City engineer for sidewalks, I checked into the guidelines of other cities with a similar climate like ours (Calgary and Winnipeg) and found that their guidelines for lips on curb cuts are specified at a maximum of 10 mm. I think if these cities can do it, we can do it here in Ottawa. For a person in a wheelchair every 1/4" of height difference can make a big difference. I therefore, suggest that a recommendation be made to the City that maximum height of lips on curb cuts be at 10 mm.
Response
These cities may specify a maximum lip of 10 mm but as explained at the September 24, 2001 meeting, this is very difficult to achieve in the field consistently due to many factors. The City of Ottawa specifies a desired lip height of 15mm but will accept a minimum height of 0 mm and a maximum height of 25 mm.
8. Include more detail in the section on the transition from sidewalk to road as often the case is the contractor just dumps asphalt and makes a soft ramp that is hard to use and creates drainage problems also.
Response
The
section shown in the design guidelines clearly shows the paved road surface and
the concrete sidewalk without any asphalt ramping. If this is done, it clearly contravenes the standards illustrated
(see detail drawing No. SC2) in the design guidelines.