One strategy for crossing streets with no traffic control is to cross with cars that cross the street from the stop sign beside you.
Rationales for this strategy are that crossing with a vehicle from the stop sign will . . .
. . . increase drivers' alertness for pedestrians.
Research is needed to verify the validity of this rationale before it can be trusted.
BUT drivers may actually be less alert because the vehicle
from the stop sign distracts them or blocks their view of the pedestrian!
. . . provide a buffer or block traffic on the main street.
This assumes that vehicles crossing streets from a stop sign remain in the street
and block the traffic on the main street long enough for pedestrians to cross.
BUT vehicles actually remain in the intersection an average of
less than 3 seconds (4 seconds for a 4-lane street). That is not enough
time to provide a buffer for the pedestrian to cross even half the street!
. . . identify a crossable gap in traffic.
This assumes that the length of gaps in traffic that drivers accept are predictable,
and are at least as long as the gap needed by the pedestrian.
BUT the length of gaps in traffic (clearance) on the main street is NOT
predictable and is NOT always as long as the gap needed by pedestrians!
Predictability of clearance from drivers waiting at the stop sign
When we know that a driver is waiting at a stop sign, can we rely on consistency to be able to predict how much clearance there is on the main street before the driver will cross it?
The behavior of drivers waiting at stop signs has been studied for many years, and research has indicated that their behavior is not consistent. The amount of clearance on the main street that drivers are willing to accept can:
- vary between geographical areas (drivers in the Mayagüez area of Puerto Rico accepted gaps that are shorter than those accepted by drivers in other regions),
- vary within individual drivers (drivers sometimes accept a gap that is shorter than gaps they had already rejected)
It can be also affected by such factors as:
- how many vehicles are waiting at the stop sign,
- how long the driver has waited at the stop sign once he got there,
- the volume of traffic on the major street,
- whether the driver is a man or a woman (men accept shorter gaps than women)
- whether the traffic on the main street travels in platoons from a signal upstream or with random gaps
- whether the driver at the stop sign is going straight or turning left (drivers going straight accept shorter gaps than drivers turning
Research to verify reliability of
street-crossing strategy
Ann Marie McLaughlin, P.E. and Dona Sauerburger, COMS
How long are the gaps in traffic when drivers cross a street or turn left from a stop sign?
Are they reliably long enough to allow a pedestrian to cross the street safely?
Study:
We observed more than 350 vehicles surge forward from 10 stop signs:
Two stop signs for crossing/entering 2-lane streets;
Four stop signs for crossing/entering 3-lane streets;
Three stop signs for crossing/entering 4-lane streets;
One stop sign for crossing/entering a 5-lane street.
Timing how long the crosswalk is clear: The strategy we were studying is to cross when the vehicle at the stop sign beside you is going straight or turning left (NOT turning right).
We found that it is not possible to know whether the vehicle is turning right until it has crossed the first lane, so we started the timer as soon as the vehicle from the stop sign had crossed the first lane.
We then measured how much time passed before a vehicle on the main street reached the crosswalk.
Results:
- 156 trials (156 vehicles started from the stop sign and turned left into the main street):
Pedestrian average crossing time: 9.5 seconds (5 seconds to cross half the street)
Clearance time on the main street after the vehicle was surging from the stop sign:
Less than 2 seconds: 13 vehicles
Less than 4 seconds: 42 vehicles
Less than 8 seconds: 86 vehicles
3-lane streets - 104 trials (104 vehicles from the stop sign crossed or turned left into the main street):
Pedestrian average crossing time: 11.5 seconds (4.3 seconds to cross first lane)
Clearance time on the main street after the vehicle was surging from the stop sign:
Less than 2 seconds: 0 vehicles
Less than 4 seconds: 10 vehicles
Less than 8 seconds: 33 vehicles
4-lane streets - 98 trials (98 vehicles from the stop sign crossed or turned left into the main street):
Pedestrian average crossing time: 16 seconds (6 seconds to cross to middle)
Clearance time on the main street after the vehicle was surging from the stop sign:
Less than 2 seconds: 6 vehicles
Less than 4 seconds: 14 vehicles
Less than 8 seconds: 36 vehicles
CONCLUSION:
