Understanding bus stops

Placement of Bus Stops In deciding just where to place the bus stop, several factors must be considered.

Fundamental amongst these is to decide if the stop is at a location where it is most useful for passengers. Another important factor to consider is the impact on the surroundings of placing a bus stop  at a particular location.

But beyond these, the placement of a bus stop is governed by the laws of traffic and pedestrian flow and of course, the geometry of the road on which the stop is desired.

pic credits: mr. gears @ flickrhttp://flickr.com/photos/mrgears/2288634149/

Understanding Bus Stops

Understanding bus stops

Conceptually all bus stops exist either before, after or in between signals. There are thus three types of bus stops: near, far and mid block.

What is the impact of these bus stop types on pedestrians and adjacent traffic? What is the impact of these bus stop types on the operation of buses themselves? What is the impact of adjacent traffic on the function of bus stops?

I am starting the discussion with a few theoretical observations, you folks chime in with your own real world observations – tarlesubba

References: Location and Design of Bus Stops on Major Streets and Highwayshttp://www.trb.org/TRBNet/ProjectDisplay.asp?ProjectID=992

PPT template for presentations, narayan82, praja

Understanding bus stops

near side stops

Main advantage is that because of zebra crossings, passengers have a systematic way to access the bus stops and similarly, other vehicles have a systematic way of dealing with pedestrian crossing.

Potentially, if the bus arrives at the signal on red, it can save time by using the red light to service the passengers. Best case stop time is thus only service time.

But it is also possible that the bus arrives at the stop when the signal is green and then may again have to sit through entire signal cycle. Worst case, is therefore service time + 1 signal cycle.

In peak traffic, the worst time is number of signal cycles to arrive at the stop + service time + possibly one more signal cycle to cross the intersection.

This might force the drivers and passengers to behave erratically like making the stop before the actual bus stop location.

Understanding bus stops

near side stops

At the same time one potential advantage is that once the bus is ready to move, it can use the free space of the intersection to immediately start moving and merge into traffic. Because of this drivers may actually pull up next to the curb at the stop.

Also if there is a queue of buses, then the bus queue will build up on the road and not on the intersection.

A stopped bus will block traffic behind it, so this can potentially conflict with vehicles turning left at the signal and possibly block traffic.

At the same time, if the cross road has major traffic and if it contributes to flow in the far side, then moving the bus stop before the intersection frees up space for the traffic moving on the far side, which is a good thing.

A stopped bus might block view of vehicles to the right of it and also block view for pedestrians.

Understanding bus stops

far side stop

Again, a fundamental advantage is the availability of zebra crossings for systematic interaction between pedestrians and vehicles. Additionally, another advantage with this design is that passengers can cross behind the bus, which is always very safe.

As far as signal timing goes, there is a potential of the bus having to stop twice – once for the red and then, immediately at the stop to service passengers. So, again best case is service time and worst case is red time + service time.

However, this design is robust to peak hours. During peak hours, the total time is number of cycles taken to cross the intersection and arrive the stop + service time. So there is a potential saving of 1 cycle time.

However, a bus ready to move to has to wait for traffic to clear before it can merge. But since all the signals are behind the bus, in the worst case the bus has to only wait for a ¼ of signal signal cycle to get a gap in flow to be able to merge into the traffic.

The buses can also use the length of the intersection to slow down in their approach to the bus stop.

Understanding bus stops

far side stop

Also, there is a potential for rear end accidents, because the buses stop immediately after the signal. However, this is risk minimized if the buses are on the left lane.

The last three reasons, including the risk of rear end accidents, might actually encourage the drivers to pull right next to the curb at the bus stop.

However, if there are multiple buses, then the bus queue might spill over into the intersection and thus potentially block traffic.

At the same time it minimizes conflict with vehicles turning left, unlike near side stops. Eventually, it can encourage regular drivers to to chose the left lane at the intersection only make left turns, because they know the bus is going to stop.

It may block visibility of vehicles turning left on the cross road. (But it should be ok if there is a signal)

Understanding bus stops

mid block stop

Since the stop is away from the intersections, there is no interference to the working of intersection due to bus stop operations.

But this design forces people to jaywalk – cross road in the middle. Since the vehicles are traveling at full speed in the middle of the block, it is very dangerous for pedestrians. At in peak time it may take forever for somebody to find the gaps in traffic to be able to safely cross the roads. It also affects dangerous situation for vehicles.

Like other bus stop types here also the best time is service service time. However, the worst time is difficult to guarantee. Depending on the nature of the road the distance to previous signal, a well behaved driver will potentially have to long periods before he can safely merge in to traffic.

This forces drivers to merge erratically creating dangerous situations for all traffic including buses.

Also unlike previous types, there are no inherent advantages to pulling over the curb. Drivers can tend to stop erratically in through lanes, especially during peak times so as to minimize waiting time to merge.

Understanding bus stops

So, what type of bus stop exists in your neighbourhood?Is it the right type for the location?