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Pedestrian

Page history last edited by Frank Broen 10 years, 9 months ago

Subject: Pedestrian crossings at roundabouts

 

The report is NCHRP 672.

Does anyone know how we may access

the referenced UNC and MN DOT studies?

 

As for MW's comments, I believe my view is somewhat different. I hypothesize

that the lower yield rate at the exit compared to the entrance is not due to

roundabout geometry and speed as much as it may be due to selfishness of

drivers and in my view, an insufficiency in driving codes.

 

 

 

Here's my logic on the first point. The driver approaching the roundabout

entrance is (should be) slowing down and preparing to stop if needed. My

opinion is this makes the driver more accepting of yielding to a pedestrian

waiting at the road edge because the driver's thought could be: I may need

to stop anyway so why not be nice and let the pedestrian cross. A test of

this theory would include observations at roundabouts with different

geometries but also would consider the available sight distance to

conflicting vehicular traffic. My contention is the sight distance has much

more influence on the yield rate than does geometry. I believe a minimum

speed geometry roundabout with excessive sight distance will produce a lower

yield rate than would a higher than desirable speed geometry roundabout with

limited sight distance. If the driver can see that he/she will not have a

vehicle conflict before getting to the crosswalk, the 'me' attitude will

likely govern and the driver will not stop for the pedestrian. In this

selfish case, I would expect the yield rate at the entrance and exit to be

similar. As for yield rates at exits, I contend that the key again is the

attitude of the driver and not the speed itself. I would expect that with

other parameters equal, drivers will yield at exit crosswalks at similar

rates whether R3 speed is in the teens or above 30 (mph). I state 'other

parameters equal' because I expect the context is of primary importance.

Driver behavior in a ped dominant environment such as an urban commercial

district is going to be night and day different than one where the motor

vehicle is dominant, i.e. suburbia USA.

 

 

 

My second point addresses how the law (and enforcement) may be modified to

help the pedestrian. I believe most USA driving codes state that the driver

shall yield to a pedestrian in the crosswalk. In this case, no moving

violation will occur until the pedestrian risks life and limb and steps into

the street. I think this part of the driving code should be revised so that

the driver shall yield to a pedestrian WAITING to cross an unsignalized

crosswalk. With that law in place AND campaigns to educate/enforce it, I

would expect yield rates to be high regardless of the roundabout's geometry

or the crosswalk being at the entrance or exit. Connecting to another

important roundabout issue in the USA, if the aforementioned (utopia) were

achieved, would the Access Board move to delete signalization of multilane

crosswalks from the PROWAG?

 

 

 

Jay Vorisek, P.E.

 

CrossRoad Engineers, P.C.

 

(317)780-1555x126


Michael Wallwork

Sent: Tuesday, June 04, 2013 10:01 PM

To: ROUNDABOUTS@LISTSERV.KSU.EDU

Subject: Re: Ped & Bike safety at roundabouts

 

 

 

Speed control requires a designer to fully understand roundabout design,

speed control design vehicles requirements. NCHRP 272 shows that exit speeds

at radial design roundabouts, roundabouts where exit speed is controlled by

the exit radius is overall well below the exit speed at Offset left

roundabouts. 

 

Two studies one by UNC and one done for the Minnesota DOFT show that yield

rates to pedestrians at the departure crosswalks decreases more so than on

the approaches due to vehicles speed, probably because vehicles are

accelerating on the exit rather than slowing on the approaches, Also, that

it only takes a few extra miles per hour to cut Yield rates from 83 to 43

percent. 

 

Michael Wallwork, PE

Alternate Street Design, P.A.

904 710-2150

 

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