In conjunction with the “Bikes Safe at Stop Sign” bill recently introduced in the Arizona legislature, I began to wonder more generally about stop signs in general (all traffic, not just bicycles).
As usual, the first stop (pun?) is to look at ARS Title 28 to see what’s what with stopping.
The stop & yield sign rule is §28-855. The rule says everyone has to STOP, and goes on to specify exactly where; depending on whether or not there is a crosswalk, stop line, etc. There is no wiggle room. (for what to do afterwards, see §28-773 — thanks eric)
I also learned that a driver approaching a driveway “within a business or residence district” (i.e. not rural) must, in effect, treat it just like a stop sign (regardless of whatever signage may or may not be there). The driveway law is §28-856. And, satisfyingly, it does specify what a driver must do after stopping.
In contrast, the yield sign rule seems much more, well, reasonable: “slow down… to a speed reasonable… and shall yield the right-of-way”. There is no arbitrary standard.
|As a confusing side story: §28-1501 has, among others, the definition ” ‘Stop’, if required, means complete cessation from movement” ; but strangely the section specifically applies “to this chapter” (referring to chapter 5 “Penalties and Procedures for Vehicle Violations”. Rules of the road like 855 and 856 are in Chapter 3.|
I was interested in finding out what proportion of drivers actually stop when there is no conflicting traffic. Traffic engineers apparently categorize behavior into 4 types. The first two comprise legal stops; Voluntary Full Stop (VFS) which is stopping when there is no conflicting traffic, as distinguished from Stopped by Traffic. The other two would be illegal; Almost Stopped, and Non-Stopping.
There was much in the Behavioral / Social Sciences literature on this.
Feest (1968), Lebbon (2007) and McKevlie (1986) observed a VFS rate of only 15%, 4.6% and 24.1%, respectively.
So it appears that somewhere between the majority and the vast majority of drivers do not stop when there is no conflicting traffic. This comports with what I have observed anecdotally.
From traffic engineering literature, the general conclusion is that compliance isn’t the problem, driver-error is. E.g. “In short, the results of many previous studies suggest that accidents at twoway stop controlled intersections are more closely related to driver error, such as failure to accurately judge the speed of major roadway vehicles, than to roadway geometry, sight distance and driver compliance with traffic control devices” (Stokes 2000)
Box and Oppenlander, 1976, (a book, i’m guessing a Traffice engineering textbook) This worksheet defines 5 levels of compliance, note that only the first two are legal, the “practically” is an expedient, 0 mph should be categorized as either VFS or Stopped by traffic, but hard to discern in the field:
- Voluntary Full Stop
- Stopped by Traffic
- Practically Stopped – 0 to 3mph
Feest, Johannes (1968) Compliance with Legal Regulations: Observation of Stop Sign Behavior. Law & Society Review, Vol. 2, No. 3 (May, 1968), pp. 447-461.This is a fun paper. Feest holds up the law about requirement of fully stopping at a stop sign when there is no cross traffic as an example of an “Unstigmatic regulation”, i.e. a rule that is frequently flaunted with little consequence. Feest found in the absence of cross-traffic “the number of people who strictly comply with the formal legal regulation is about 15 per cent”, and that the large majority made either a “rolling stop” (58%, 2-10mph) or “half-stop” (22%, 10-20mph). These categories taken from a pamphlet used for training law enforcement officers.
Lebbon, A.R., et al (2007) Evaluating the Effects of Traffic on Driver Stopping and Turn Signal Use at a Stop Sign: A Systematic Replication. Journal of Organizational Behavior Management, Vol. 27(2) 2007.
McKelvie, S. J. (1986). An opinion survey and longitudinal study of driver behavior at
stop signs. Canadian Journal of Behavioral Science, Vol. 18(1), pp. 75-85. “most drivers stopped when another vehicle was in the vicinity and most only slowed when the road seemed clear. It is concluded that stop sign behaviour reflects risky decision-making rather than adherence to the law…”. For observational result of 24.1% VFS, see Table 3. One hiccup is they defined what they termed a Complete Stop as stationary for 2 seconds, with is supra legal.
McKelvie, S. J., & Schamer, L.A. (1988). Effects of night, passengers, and sex on
driver behavior at stop signs. Journal of Social Psychology, 128(5)(Oct 1988), pp. 685-690. “Despite the legal requirement that drivers come to a complete halt at stop signs… absence of other vehicles lowers (compliance) to 15%”
Mounce, JM. (1981) Driver Compliance with stop-sign control at low-volume intersections. Transportation Research Record (TRB) No. 808. pp 30-37. To paraphrase from the abstract: compliance (a full stop, whether you need to or not) is high when there is a lot of conflicting traffic, and low when there is little traffic. And in addition, if the sight line is good, compliance is lower. (which of course makes perfect sense) “The results from 2830 observations at 66 intersections indicated that the violation rate decreases with increasing major-roadway volume and is significantly high (p < 0.001) up to the average-daily-traffic (ADT) level of 2000 and significantly low (p < 0.001) above the ADT level of 5000-6000. An interaction effect between major-roadway volume and minor-roadway sight distance results in a violation rate that is significantly higher (P < 0.05) when sight is unrestricted than it is when sight is restricted”
Bretherton, MW. Multi-way Stops – The Research Shows the MUTCD is Correct! http://www.troymi.gov/TrafficEngineering/Multiway.htm retrieved Feb 08, 2009. This paper focused on why it is undesirable to use stop signs for the purpose of speed-control, but it has loads of references.
Stokes, RW et al, (2000) Analysis of Rural intersection Accidents Caused by Stop Sign Violation. Report No. K-TRAN: KSU-98-6. Had this to say about stop sign compliance (emphasis added): “The results of this study (and previous studies) suggest that disregard for Stop signs and other traffic control devices is not the primary cause of accidents at rural two-way stop controlled intersections. The majority of the accidents appear to be due to drivers who enter the major roadway and do not (or cannot) accelerate quickly enough to avoid being struck by major roadway vehicles. This would suggest that drivers on the minor roadway either did not see oncoming vehicles or failed to accurately estimate the speeds of oncoming vehicles on the major roadway” … “In short, the results of many previous studies suggest that accidents at twoway stop controlled intersections are more closely related to driver error, such as failure to accurately judge the speed of major roadway vehicles, than to roadway geometry, sight distance and driver compliance with traffic control devices“
Here is what the MUTCD says about stop signs. Only tangentially related to the issue at hand, there is a lot of controversy about placing so-called unnecessary stops (e.g. placing stops on the busier road, or adding extra all-way stops) — MUTCD guidance states flatly “STOP signs should not be used for speed control.”
In a paper that surveys various traffic calming measures [Traffic Calming: State of the Practice Reid Ewing, August 1999], makes reference to data from Department of Transportation, “Brentford Lane—Stop Sign Compliance
Study,” Gwinnett County, GA, September 1997. A pie chart is presented for compliance with all-way stops: 59.3% Rolling Stop, 22.2% Slowed Down, 11.1 Complete Disregard, and a grand total of 7.4% COMPLETE STOP.