Thursday, August 27, 2020

To Tunnel Or Not To Tunnel, That Is The Question

Acequia/Rail Trail Tunnel. Santa Fe New Mexican photo

On 25 August, the Santa Fe New Mexican published an article about attacks on pedestrians in and around the pedestrian tunnel crossing St. Francis Drive just north of the St. Francis/Cerrillos intersection. This tunnel provides partial grade-separated connectivity between the segments of Rail Trail on opposite sides of St. Francis Drive and grade separated access to the Acequia Trail from the Railyard. Some commenters responding to the article and at least one Councilor criticized building tunnels due to their seeming to be a magnet for homeless people and the criminal element. So we have a tug of war at play between grade-separated access to the city's bike/ped trail network that reduces car-bike and car-pedestrian conflict vs. designs that sometimes lead to street crime. 

But let's not forget that the criminal activities have been in several locations along the Railyard-Acequia Trails alignment, not just in the tunnel. Crime is a bigger problem than an issue due to a tunnel alone.  I'd like to see an official, SFPD crime map of Santa Fe to see if this area actually stands out in terms of crime frequency as opposed to being magnified beyond actual risk due to a high profile article in the newspaper. We have seen assaults in other parks and Downtown. My suspicion is that the criminal element sees isolated pedestrians as easy targets, regardless of location and that good trails attract pedestrians, aka targets. Perhaps we need some undercover cops dressed looking like easy marks wandering our trails, aka a Detective Belker.

Now, on to some basic multimodal transportation issues. It is well known in the bicycle-pedestrian design and advocacy community that you cannot expect to have your bicycle transportation system enthusiastically utilized by average citizens (as opposed to "serious cyclists") if it has intimidating choke points on it. These have to be circumvented with good designs. Santa Fe is a city sliced in pieces, bicycle design-wise, by major highways ("principal arterials") that were not designed to effectively accomodate pedestrian or bicycle travel. St. Francis, Cerrillos, and St. Michaels are all fast multilane principal arterials currently controlled by the State of New Mexico Dept. of Transportation and are, in my opinion, designed to move as many cars as efficiently as possible rather than optimizing access to all modes of transportation. There are no bike lanes on St. Francis, for example, a design deliberately approved more than a decade ago by the NMDOT against the wishes of the bicycling community. The St. Francis-Cerrillos intersection is further complicated by the diagonal crossing of the Rail Runner track alignment, which can trap the wheel of a cyclist trying to cross as traffic. Indeed, any at-grade crossing of a major highway by a person on foot or bike is somewhat risky, as the fatal crashes at St. Francis and Zia as well as elsewhere demonstrate. That is why grade-separated crossings on busy principal arterials are strongly recommended in spite of their often considerable cost. 

Indeed, at a recent Santa Fe BTAC meeting, a 2018 crash analysis was discussed that pointed out that "... the main contributing factor (to crashes between motorists and bicyclists) is a failure to yield on behalf of both the bicyclist and motor vehicles (33%) and second was driver inattention (19%). Bicycle crashes are predominantly at intersections (64%); incidents are disbursed across town but generally on arterials: Cerrillos Road 45%; Airport Road 17%; St. Francis Dr. 13%; and St. Michael's Dr. 9.4% and primarily on weekdays." Hence the need for safer designs consistent with the Vision Zero concept that one engineers roads to protect against likely human error.

 There is a side benefit to motorists in these separated facilities, as they increase motor vehicle level of service, since there is no requirement for a long red light cycle when pedestrians are crossing wide streets if pedestrians have their own right of way. The Manual of Uniform Traffic Control Devices (2009) estimates a speed of 3.5 to 4 feet per second for pedestrians crossing a street but some recent research suggests that is too fast for almost half of older pedestrians and some younger ones. So on a 130 foot principal arterial such as St. Michael's Drive, a pedestrian walk light can stop busy traffic for approximately 37 seconds and this timing may increase as our population ages.

So to make Santa Fe's network of bike-ped trails functional, we need grade separated crossings on principal arterials and highways. How to do it is the question. Tunnels are protected from the weather to some degree and can be compact, since they need only provide enough headspace for people rather than sometimes huge commercial vehicles. Of course a tunnel provides protection against the elements for everyone, including homeless people looking for refuge. Bridges, by contrast, are exposed during foul weather and winter conditions and would require more maintenance during winter weather to provide year round connectivity if snow and ice are present. Furthermore, they can be massive. The Federal Highway Administration requires a minimum of 14-16 feet of overhead clearance for a bridge over an arterial so that large trucks can pass underneath. Meanwhile, the Americans With Disabilities Act stipulates a gradient on ramps no steeper than 1:12 (one foot of rise for every 12 feet of distance). This results in ramps leading to an overhead crossing that could be more than 200 feet long. In an analysis of building a pedestrian bridge over St.Michael's Drive prepared for the State in 2014 by Souder, Miller, and Associates, approach ramps to the overhead structure were listed as being approximately 350 feet long to provide for a bridge with 16' of clearance over the road. So access to a substantial easement is required.  The bottom line? Nothing is cheap or without costs as well as benefits and sometimes you need a pretty big hammer to make it fit.

Given the planing for a tunnel at the Rail Trail crossing at St. Michael's drive, which is currently an uncontrolled midblock crossing of a multilane, fast arterial, we need to come to some consensus on whether the city will support these or other designs with enforcement, maintenance, and also to assist in providing better shelter to the homeless. Plus, these are not the only tunnels in town. There are several small but critical tunnels along the Chamisa Trail and one near the Zia station for a spur off of the Rail Trail as well.

Given that our arterial system carves up Santa Fe and impedes bike-ped mobility, grade-separated crossings are necessary to make our trail system work. Tunnels provide advantages in cover as well as space but can also attract a criminal element and the homeless. Bridges require a lot of space, which is sometimes an issue. Neither are cheap. As a cyclist and a citizen of this city, I don't want to see these tunnels turn into something the public fears or despises. And as a cyclist and someone concerned with multimodal transportation, something important to public health, urban planning, and environmental protection, we need to make the bikeway system not only efficient but desirable rather than something putting fear into people's heart. We need to solve this problem.

More reading: The Underpass Dilemma.

Yet more reading.

Neighborhoods and Trails: Why Trails?

Prepared by Margaret Alexander for the Santa Fe Conservation Trust January, 2009;
Updated April, 2010

 

1 comment:

Desert Dirt said...

This is a great summary of the issues and key points. I'm a strong advocate for cycling/pedestrian infrastructure in Santa Fe and am amazed at the many additions that have gone in over the last 10yrs. Bike paths and tunnels do not create crime any more than parks and being out after dark might create similar circumstance. The fault belongs with those that harass and assault others. To substitute a bridge in place of a tunnel is a very poorly thought out alternative and I say this having lived in towns that had done so (far easier to cross at grade).

Glad to learn that someone as familiar with the issues as yourself sits on BTAC.