Bus stop capacity

Bus stops play a critical role in determining the capacity and service quality of bus services. While bus stop capacity will not be relevant for many bus stops in New Zealand, consider the hourly capacity of bus stops required on high volume bus corridors or at stops with particularly long dwell times.

Bus stops determine the overall capacity of a bus route, so it is critical for bus stops to be designed to have sufficient capacity for the planned number of bus services along the route.

Bus stops with insufficient capacity will force buses to queue on the road, causing delays for bus passengers and negatively impacting road safety and passenger accessibility.

Length of time a bus spends occupying the bus stop

The length of time a bus spends occupying a bus stop is called dwell time.

Dwell times of less than 30 seconds are optimal from a bus capacity perspective. Longer dwell times incrementally reduce bus stop capacity.

Factors that influence dwell times, include:

• the average number of passengers getting on and off each bus – the more passengers, the longer the doors need to be opened and closed and the longer it takes passengers to get on and off, so the longer the dwell time
• the mix of fare payment methods – the more methods (especially if one is cash), the longer the dwell time
• the number of doors used for boarding – one door means a longer dwell time than two doors
• whether the stop is a timing point – if so, the bus may spend time idling in the stop, which means a longer dwell time. This can reduce ‘live’ bus stop capacity more than what one expect based on volume of passengers alone
• whether the stop is a transfer point – if so, it requires at least two buses to occupy the bus stop at the same time to enable passenger connections, which lengths dwell time
• factors that affect bus re-entry into the traffic – whether there’s a dedicated bus lane the bus would be entering or if it would be trying to re-enter a high-volume mixed traffic lane - the latter would increase dwell time

PTDG: Timing point bus stops

Presence and timing of nearby traffic signals

Placing bus stops near intersections with traffic signals facilitates walking access to and from the bus stop, but it also reduces bus stop capacity. When a bus stop is located at a signalised intersection or crossing, if the light is red, buses cannot:

• leave the stop immediately after passengers have got on and off (at approach or near-side stops)
• enter the bus stop (at departure or far-side stops).

The impact of a traffic signal on bus stop capacity is determined by the green time ratio; that is, the proportion of bus green time to total traffic signal cycle length. The higher this ratio, the more capacity a bus stop has. The figure below illustrates the difference between a 25 percent and 50 percent green time ratio.

Impact of a traffic signal's green time ratio on bus stop capacity.

For near-side stops, dwell time that occurs during the red phase does not affect capacity, because the bus would not have been able leave the stop during this time anyway. Compared with near-side stops, far-side stops can have a larger impact on bus stop capacity because dwell times and red signal times cannot overlap.

If traffic signals are significantly reducing bus stop capacity, consider mitigating the effect by:

• increasing the green phase length for the bus direction of travel
• pairing the active signal priority with a near-side stop so the green phase is coordinated with the bus’s departure from the bus stop.

PTDG: Public transport priority and optimisation

Type of bus stop provided

Where more than one bus at a time is required at a bus stop, the stop may be one of three types: split, linear, or sawtooth (see figures below). Each type has different implications for bus stop capacity.

• Split stops have a linear design where bus stops serve separate bus routes and have separate entry and exit tapers (lead in and lead out space), so buses can enter and exit independently of each other.
• Linear stops have a linear design where multiple bus stops are stacked linearly. Multiple bus routes share the same bays and buses need to wait for the bus in front of them to leave before they can move.
• Sawtooth stops have a non-linear design that allows buses to enter and exit the bus stops independently of each other. Usually, these bus stops are at an angle to the roadway and off the street (for example, at an interchange).

The advantages, disadvantages and practice guidance for each stop type are summarised below.

Stop type: split

Example layout: split stop with independent operation.

Bus stops by Wellington Hospital are split for multiple routes. (Source: Nadine Dodge)

Advantages

• Provides high capacity as bus bays do not interfere with one another
• Enables buses on different routes to use separate stops
• Reduces bus-on-bus delay
• Splits up waiting areas, supporting space efficiency
• Can reduce the distance customers have to walk between the ‘top’ of the stop and their bus arrival location
• May allow customers to better see oncoming buses

Disadvantages

• Can be less intuitive for customers who may not realise they are waiting at the wrong bus stop!
• Can take drivers a little getting used to
• May require more kerb length which may reduce the amount of on-street car parking
• Is feasible only on streets with sufficient space for buses to overtake one another safely

Practice guidance

• Independent manoeuvrability is essential for stop splitting (that is, a bus needs adequate room to pass another bus at the bus stop and pull in and out)
• Stops may need to be split just to support customer visibility
• Real-time information is highly recommended for split stops
• Bus routes with common destinations/routes should share the same stop

Stop type: linear

Example layout: linear stop with dependent operation.

Example layout: linear stop with semi-dependent operation (bus can exit but another bus cannot enter the space without relocating other buses).

Advantages

• Increases capacity compared with single bus bays
• Reduces the amount of kerb space required
• May be more intuitive for passengers, especially when many bus routes can be used for a journey

Disadvantages

• Provides less capacity than sawtooth or split stops; capacity depends on a bus stopping at either end (that is, a bus at the rear end must wait for the bus ahead to exit first, and vice versa for buses entering)
• Passengers may have difficulty knowing where to wait, and buses may have to pick up passengers at multiple points along the length of the bus stop

Practice guidance

• Real-time information is highly recommended to assist customers
• Sufficient waiting area space must be provided for the number of passengers

Stop type: Sawtooth (off-street sites only)

Example layout: sawtooth - angled bus stop parking.

Example layout: perpendicular parking.

Advantages

• Provides high capacity as bus stops do not interfere with one another Allows different routes to be assigned different stops
• Minimises confusion, if it has good signage and information

Disadvantages

• Increases the time it takes the bus to exit the stop (clearance time) since buses may need to reverse
• Requires reversing which needs to be well managed for safety
• Requires more length per stop

Practice guidance

• Not suitable for on-street bus stops (see Public Transport Design Guidance topic Public transport interchanges)

Number of bus stops provided

If it is not feasible to increase bus capacity by reducing dwell time or signal delays, consider adding additional bus stops. Base decisions on additional bus stops on a mixture of:

• the number of scheduled buses per hour relative to capacity
• on-site observations of the actual performance of the bus stop
• communication with public transport service operators.

Bus stop capacity should be well above scheduled hourly bus volumes to allow for efficient operation, even when some buses have longer than average dwell times.

The figure below shows the indicative hourly capacity of bus stops away from traffic signals, assuming average dwell times of 30, 60 and 120 seconds.

If operating conditions allow for dwell times of 30 seconds or less, one or two bus bays should provide adequate capacity for almost all bus stops in New Zealand, with a capacity of 68 buses per hour with one bay, 120 per hour with two linear bus bays, and 136 per hour with two split bays.

If a bus stop has dwell times of 60–120 seconds, bus capacity is dramatically reduced to 20–26 buses per hour per bay. If the stop also serves as a timing point or layover and experiences longer than normal dwell times, it may be desirable to provide additional bus bays to ensure adequate capacity.

Capacity of bus stops away from traffic signals. (Source: Nadine Dodge, using data from Transit Capacity and Quality of Service Manual (3rd edition))

The figure below shows the indicative hourly capacity of bus stops at traffic signals, assuming a green time ratio of 0.5 and average dwell times of 30, 60 and 120 seconds.

With a 0.5 green time ratio, traffic signals can be expected to reduce capacity at near side bus stops by around 30 percent, although this will vary depending on dwell times. For bus stops on the far side of the traffic signal, a 0.5 green time ratio would reduce capacity by 50 percent.

Capacity of near-side bus stops at traffic signals. (Source: Nadine Dodge, using data from Transit Capacity and Quality of Service Manual (3rd edition))

Transit Capacity and Quality of Service Manual (3rd edition)(external link)

Related information

For further information about bus stop layouts including the advantages and disadvantages of kerbside, in-lane with bus boarders, or indented bus stops refer to: Bus stop layout