Plamondon’s design for the downtown hotel’s twin 2-way driveways side by side on East Patrick St breaks rules in federal, state and city rulebooks for access to an arterial/collector class road. The Plamondon site plan shows two 2-lane driveways on East Patrick Street. The westerly driveway’s western edge is only about 75 feet from the signalized intersection with Carroll Street. There is a further 100ft to the Eagles building but the eastern edge of the proposed eastern driveway is 155ft from the intersection.
The design fails safety tests on multiple counts.
It is so close to the signalized intersection exiting traffic from the hotel garage conflicts with traffic turning left from Patrick into S Carroll St. Its closeness to the intersection also means that traffic exiting the hotel garage will often be blocked by queueing traffic at the the intersection signals or ‘traffic lights.’ As few as seven or eight cars queued at the Carroll Street signals would completely block both Plamondon driveways.
There are multiple ‘conflict points’ caused by the driveways themselves with entering traffic required to cut across exiting traffic in each of the two Patrick St driveways.
Conflict points are the highway engineer’s term for locations on a roadway where travel paths of different vehicle movements cross one another, and therefore are potential crash generators.
The driveways in the site plan in HPC17-491 have what are known as left-in/left-out access points. Given the westbound one-way traffic on Patrick St access points on the southern side are awkward left-in/left-out movements which set up a conflict point for the two directions of traffic of each driveway. Entering traffic has to cross the path of exiting traffic on the left side of a one-way street, unlike at a right-in/right-out driveway on the right side of a one-way street.
A further problem is that the two 2-way driveways present a hazard for pedestrians using the sidewalk of East Patrick St. A pedestrian has to twice watch both directions of traffic and cross the equivalent of two streets. The twin driveway plan is hardly consistent with the idea of the downtown as a pedestrian-friendly ‘walkable’ place.
City’s Land Management Code calls for 150 ft from driveway to Carroll St
City rules driveways are laid out in the Land Management Code, Section 601, Access Management whose purpose is stated: “This section regulates the amount and nature of vehicular access points in order to balance the need for providing access on City-owned roads to individual private properties with the need to preserve an adequate level of capacity on the streets providing access.”
Minimum spacing standards are set out in Table 601-2, Separation Standards. The last item shows a minimum distance between two driveways as 50ft on a local street, 100ft on a collector and 200ft on an arterial. Patrick St is classified on City maps as a minor arterial but the proposed service driveway and the parking basement driveway don’t even meet the 50ft separation, measured centerline to centerline, required on a local street, let alone the 100ft on a collector or the 200ft on an arterial.
The Separation Standards in the City code provide for a driveway to be a minimum 150ft from a local street (Carroll St) on a collector street and 400ft on an arterial. If as minor arterial is treated as a collector then the 150ft distance required to Çarroll St would push the only driveway allowed right up against the Eagles building. That kills the service driveway for tractor trailers.
State money is involved so the matter is not solely a City decision. Although originally a state highway and still designated MD144 Patrick Street east of US15 is a City road.
Maryland Department of Transportation’s SHA Access Manual 1.3.1.B on commercial sites with short frontages states: “Commercial sites with under 400’ of frontage will be limited to a single point of access unless otherwise warranted by demonstrated traffic operations or site circulation considerations.”
Chapter 1 on Access Point Standards has at 1.4.2 Spacing between entrances: “A minimum 20’ tangent is required between adjacent entrances on the same side of the highway, under any circumstances.”
Table 1.4.3 Corner Clearance Standards shows the Plamondon plan with a driveway at 75 feet is less than the minimum corner clearance of 100ft for a secondary arterial and much less than the 200ft preferred corner clearance.
1.7 lists other factors to be considered in the State Highway Administration’s evaluation of proposed access points to a state highway and included is “Availability of access on lower-type road.” Carroll Street is a lower-type road and of course the Plamondon plan shows access off it. That is another strong reason for the state to deny access off East Patrick so close to the intersection.
USDOT, Federal Highway Administration’s technical summary ’Access Management in the Vicinity of Intersections’ provides guidance to road designers and regulators. Arguments against the driveway design of Fillat + Architecture:
“Limiting or, where possible, eliminating driveways within the functional area of an intersection (upstream and downstream) helps reduce the number of decisions motorists must make while traveling through an intersection and improves safety…” A Utah DOT study is cited that found crash numbers and severity correlate strongly with driveways located in the “functional area of intersections.” Both Patrick St driveways in the Plamondon site plan are located well within the ‘functional area’ of the intersection with Carroll Street, defined as the area in which motorists are getting positioned for a turn or queueing at a red light (or signal in engineerspeak). p3
More FHWA guidance:
“It is desirable to minimize the number of conflict points created with existing and future driveways since more conflict points increase the risk of crash occurring.” 1.3, p3.
Left-in/left-out driveways unfortunately add a conflict point. This is more important on Patrick St as an arterial road because of higher volumes and speeds than on Carroll Street which is local with smaller volumes and vehicles moving more slowly.
“Research over the past decades has consistently shown that crash rates increase as driveway density (i.e. number of driveways per mile) increases…” Nine studies are cited all of which show upward sloping curves of crash rates per mile travelled against access points/mile. 1.6 p5.
The City Planning Commission seems likely to force Plamondon to redesign access and vehicular circulation on the site, if the plan ever gets to them.
They are likely to nix the twin access points on East St, specially the western one, the one closest to Carroll St. They could bar both Patrick St driveways, requiring a new location for the access ramp to the basement parking garage.
Historic preservation concerns about Patrick St frontage
Historic preservation officials have already criticized the Patrick St driveways. Commissioner Carrie Albee in the first workshop said there seemed to be excessive space devoted to internal roadways and parking especially in light of the developer’s push to demolish. City historic planner Lisa Murphy said the hotel building would fit the historic design guidelines better if it continued the street’s building frontage along the Patrick St sidewalk. Instead it devotes the frontage to four lanes of driveway.
Plamondon in their winning bid in 2014/2015 claimed to have completed a traffic impact study for the site. But the study has never been released and there must be doubts it ever existed. It is difficult to imagine qualified traffic engineers even thinking about twin left-in/left-out driveway access points side by side on Patrick St.
(EDITING: this report has been edited twice since originally posted July 25. Patrick St east of US15 is under City jurisdiction although signed as a state route MD144. Once the National Road it has devolved down to state and now city responsibility as US40 then I-70 developed to replace it as the major east-west road through Frederick.)
City of Frederick Land Management Code, Section 601, Access Management:
MDOT SHA Access Manual:
Access Management in the Vicinity of Intersections, Federal Highway Administration, Office of Safety:
at issue is the Site Plan drawn by Peter Fillat + Architecture which is part of HPC17-491
PSam original post 2017.07.24 Latest revision 2017.08.21