3.4.1 Measures for the Location of Bus Stops
According to EAÖ—FGSV (2003), the determination of bus stop location is generally influenced by the requirements of passengers, the interest of public operators and other road users, and local conditions. These factors are given as follows:
• The requirements of passengers: short distances from origin or to destination; safe and comfortable accessibility for all passengers.
• The interest of operators: undisturbed movements to bus stops; short passenger exchange time; desired overlapping transfer time; acceptable waiting time at traffic signals; adaptation to signal coordination; signal aids for leaving stops; and reasonable stop distances.
• The interest of other road users: capacity of intersection approaches; queue length after stopping buses; pulling out/into general traffic flow; positions of pedestrian crossing (regarding visibility between motorists and pedestrians near stopping buses); turning conflicts between buses and other vehicles; the guidance of bicycle traffic; visibility between motorists and cyclists within the intersection area; and requirements of pedestrian traffic for sufficient walking paths and waiting areas.
• Local conditions: existing roadway conditions; intensity of land use; and requirements for bus stop design.
Longitudinal Location
Basically, the location of bus stops along the roadway is classified into three types: stops before intersections (near-side stops), stops behind intersections (far-side stops), and stops away from intersections (mid-block stops).
Generally, bus stops are located in the range of intersections or near pedestrian crossings. The location of bus stops must be examined in order to provide passengers with safe, easy and
comfortable accessibility. Besides, the clarity of bus stops should be taken into account in order to permit road users to adjust their movements early in agreement with the prevailing traffic situation at the stops. For this reason, the visibility of all road users must be checked carefully. [EAÖ—FGSV (2003)]
Stops before the intersection might cause additional delays for buses since they can miss their green intervals due to their variable dwell times. If these stops are used in combination with bus bays, special signals for leaving aids should be implemented to provide buses with leading green times. Otherwise, stops behind the intersection have some advantages, for instance, signal priority in response to bus requests can be switched more reliably, variable dwell times at stops will not have considerable impacts on bus delays. Furthermore, these stops can provide the better visibility for passengers, pedestrians, and approaching vehicles. [RiLSA—FGSV (1992); EAÖ—FGSV (2003)]
According to the German Guidelines for Traffic Signals [RiLSA—FGSV (1992)], if neighbouring signal programs are coordinated, stopping time of buses at their stops should be coincided with red periods between the end and the beginning of two successive green bands. By arranging bus stops alternatively before and after signalised intersections, it enables buses to join Green Waves of private traffic from a near-side stop at a given intersection until a far-side one of the following intersection.
Vuchic (1981) indicated that there are several factors influencing the choice of bus stop location. Among these factors, signal coordination should be taken into account since it can have a notable effect on the speed of buses. Besides, the accessibility of passengers must be carefully considered, i.e. stops should be located where waiting passengers are protected safely from other traffic, space for circulation must be sufficient, the pedestrian flow on sidewalks must not be impeded, and walking distances between stops should be examined for transferring between different bus lines. It is desirable to select the positions which minimise interference (e.g. interference caused by turning, merging, and re-entering movements) and safety hazards.
Demetsky et al. (1982) conducted the evaluation on the location of bus stops, which was based on the judgements provided by city traffic engineers and transit operators. Several factors were used in this evaluation, including bus stop spacing, bus stops in market areas, transfer points, the safety of passengers, the interaction between bus and other traffic, impacts on traffic operation, impacts on general traffic, and effects on adjacent land use/development. The result of their study indicated that far-side stops are more preferable than near-side and mid-block ones.
Transportation Research Board (1996) recommended that the determination of bus stop location involves the selection between near-side, far-side, and mid-block stops. This selection is often influenced by a number of factors such as passenger origins and destinations, pedestrian access, potential patronage, bus route, intersecting transit routes, signal priority, traffic control devices, intersection geometry, impact on the intersection operations, parking requirements, presence of queue jump lanes, physical road side constraints, and adjacent land use and activities.
It is apparent that the selection of bus stop location is influenced by a number of factors. At heavily loaded signalised intersections, the factors with respect to capacities and traffic flow
quality of intersection approaches involved cannot be disregarded, particularly under the condition in MDCs. However, the available calculation of the impact of bus stops seems to contain some simplifications which might be not appropriate for MDCs. This issue is clarified more in the following discussions.
In the United States, according to Transportation Research Board (2000), the impact of an on- line bus stop on capacity at traffic signals is formulated by an intended reduction in the saturation flow rate of the subject lane group. This reduction is represented by an adjustment
factor for blocking effect (denoted by fbb). The calculation of this factor is based on the
assumption of an average blockage time of 14.4 seconds during the green interval. The value of this factor depends primarily on number of lanes in the lane group and number of buses stopping per hour at bus stops. However, a simplification was made for that impact since this factor is set equally within the ranges of 250 ft (approx. 76 m) from the upstream or downstream intersection. That means both near-side and far-side bus stops within those ranges have the same impact on the subject lane group; further than those ranges, however, that impact is not considered.
In Germany, with reference to the “Handbuch für die Bemessung von Straßenverkehrsanlagen” [Manual for the Design of Road Infrastructure, HBS—FGSV (2001/2009)], the impact of on- line bus stops is not taken into account at traffic signals. The reason for this simplification might be derived from reasonable traffic loads at signalised intersections in German cities. Besides, when bus volumes are high, they are normally separated from other vehicles due to their right- of-way policies in the planning phase.
It should be remarked that the mentioned simplifications can be reasonably acceptable in industrialised cities because of their prevalent conditions. However, under the condition of mixed traffic flow (dominated by motorcycles) and heavy traffic loads in MDCs, the impact of bus stops might be largely different, corresponding to different positions of bus stops near traffic signals. Thereby, an in-depth study on this issue will be conducted in another chapter.
Latitudinal Location
The latitudinal location of bus stops in cross sections of roadways can be classified into two major types: curb-side stops (stops in the edge of streets) and median-side stops (stops in the middle position of streets).
Curb-side stops are commonly used when buses operate on curb-side bus lanes or mixed traffic lanes. Differently, median-side stops are basically used for median-side bus lanes, and they generally require combined islands for the passenger boarding and alighting. Compared to curb- side stops, median-side ones need more considerations regarding the safety and accessibility for passengers.
In MDCs, most of bus stops are curb-side stops which are located on mixed traffic lanes. Therefore, this research will focus mainly on this type of bus stops.
3.4.2 Other Measures for Bus Stops
Type of Bus Stops
Bus stops can be situated directly on normal traffic lanes (on-line stops) or outside those lanes with bus bays (off-line stops).
An on-line bus stop, which is situated directly on a travel lane, is the portion of a roadway marked or signed for the use of buses when loading or unloading passengers. Generally, there might be several loading areas at a bus stop, depending on the rate of bus arrivals and passenger service time at that stop. [Transportation Research Board (1996)]
Differently, a bus bay is a specially designed area which is separated from travel lanes and off the normal section of a roadway. It allows other vehicles on those lanes to flow freely regardless of stopping buses at their bay. Therefore, bus bays are highly recommended on roadways operating with high volumes or high speeds, such as suburban or arterial roads. Generally, the selection of this measure is influenced by the following factors: traffic volumes on the curb lanes, travel speed, bus volumes, passenger volumes, dwell times at bus stops, potential accidents for passengers at stop location, potential conflicts between buses and cars, sight distance, etc. Depending on the location of bus bays relative to intersections, there are far-side, near-side, and mid-block bus bays, in which a far-side placement is desirably suggested. There can be different types of bus bay design, including typical bus bay, open bus bay, partial open bus bay, and queue jumper bus bay. [Transportation Research Board (1996)]
In MDCs, the most common type of bus stops is on-line stops which are located directly on mixed traffic lanes. These bus stops often cause a number of problems for both buses and other vehicles at traffic signals. For this reason, problems of these stops and measures for them in the condition of MDCs will be studied in the following chapters.
Stops with Curb Extension
This measure can be applied to streets having curb-side parking lanes and operating with high lateral traffic volumes. In this case, a provision of curb extension will benefit buses by time savings when they enter their stops and re-enter travel lanes, especially during peak periods. Besides, illegal parking or stopping activities in the range of stop areas can be also prevented by an installed curb extension. Another advantage is that a bus stop with curb extension needs smaller space than a bus bay. Besides, this measure contributes to enhance safety, comfort, and accessibility for passengers. [EAÖ—FGSV (2003)]
Boarding Islands
Boarding islands assist buses in reducing unnecessary delays in multiple lane streets where parking activities, slow traffic, and delivery traffic on curb-side lanes are permissible, and right- turning traffic on the bus approach is heavy. These islands allow buses to dwell between travel lanes so that they can use a faster lane for entering stops and merging into travel lanes from their
stops (see Fig. 22). However, if this measure is applied, the safety and accessibility for passengers must be considered carefully. [Transportation Research Board (2003b)]
a. Before the implementation b. After the implementation Figure 22: Example of boarding island
[Source: Transportation Research Board (2003b)]