Urban Street Design Elements: Medians, Parking, and Lanes
Medians and Central Reservations
The median or central reservation is defined as the longitudinal separation between carriageways on very wide streets when they are not passable. Its installation has advantages and disadvantages.
Advantages:
- Increased safety measures.
- Allows for future expansion of roadways.
- Provides visual separation (rupture).
- Serves as a pedestrian refuge.
- Acts as a barrier to nuisance traffic.
Disadvantages:
- Decreases the useful section of the road.
- Can sometimes be a barrier to the movement of pedestrians.
Dimensions:
Its size depends on the function it is intended to serve:
- Minimum (Lane Differentiation & Signs): 0.50m to 0.80m is the recommended minimum to differentiate lanes and place traffic signs.
- Pedestrian Refuge: Should be between 1.80m and 2.00m.
- Landscaped Medians (Minimum): From 3.50m to 4.00m.
- Enabling Steps and Landscaping: Requires 12m.
Two-Way Street Widths
Two-way streets must have a width of 5.50m when accommodating two vehicles traveling in opposite directions. This can be reduced to 4.80m if only two cars typically circulate.
Cul-de-Sacs
Cul-de-sac streets are not continuous and are designed to enable vehicles to change direction (turn around). Their length should not be excessive and must generally not exceed 80-100m. The widths of these roads range from 4.00m to 5.80m. Parking should typically be avoided in them.
Parking Space Design
The factors that determine parking space arrangement are:
- The type of vehicle.
- Whether a maneuver is required to enter the space.
- Average length of stay.
- The type of street.
To ensure maneuverability and access, consider the type of vehicle that will normally be parked.
Dimensions:
- Standard: 2.40m x 5.00m
- Minimum: 2.20m x 4.50m
- Handicapped: 3.30m x 4.50m
Parking Types:
There are several types of parking according to different criteria:
- Arrangement of spaces: On-street (parallel), angled (oblique), or perpendicular (battery).
- Relation with the road: On the road or off the road.
- Integration in the road: In a separate band or not.
- Delineation of spaces: Painted boundaries, trees, etc.
- Continuity: Continuous or discontinuous spaces.
- Function: Residential, commercial, workplace, etc.
- Duration, regulation, and control: Parking meters, time limits, etc.
Angled parking is usually set at 30°, 45°, or 60°, although each angle has its advantages.
Street Design and Public Transport
Streets must accommodate public transport surface needs. The specific design approach depends on the type of street. It is common not to make a specific distinction for a bus lane.
Bus Lane Considerations:
The lane where the bus circulates should ideally be 3.80m to 4.00m wide. Special attention must be paid to solving turns at intersections.
Bus Stops:
Stops are typically placed at a distance of 300m to 600m apart, often located near intersections and close to the curb. In other cases, it is preferable to place stops in an auxiliary lane, particularly at the end of lines or for multiple stops.
Dedicated Bus Lanes:
In the case of a reserved bus lane, the recommended width is 3.50m. This lane must carry some kind of road marking or be separated by curbs indicating the segregation of this lane.
Street Design and Bicycle Lanes (Cycle Paths)
The bike lane (cycle path) should not be seen merely as a leisure space or for pedestrian use but, like other transport infrastructure, as a space for connecting points. This means that the bike path should be considered as important as the driveway or sidewalk in planning.