This dinonline.org article implies more "contemporary" rabbanim, namely Rav Shlomo Auerbach and Chazon Ish, who indicate that Tefillat Haderech should be recited even when travelling on foot, but without a bracha if you are travelling in most cities. However, if you are walking through a known dangerous area (I guess certain areas of New York City that are considered high crime areas would qualify), then you should recite with a bracha. I'm excerpting some parts:
It does not matter whether one travels by foot, automobile, boat,
train or airplane. As long as the trip consists of the minimum
distance, tefilas haderech is recited. (Mishnah Berurah 110:30, Sefer
Ishei Yisrael chap. 50, footnote 5, Sefer Tefilah K’Hilchasah 27:27,
Shu”t Be’er Moshe vol. VII chap. 114:1)
In earlier generations intercity roads passed through desolate and
totally unpopulated areas. Therefore, the danger of highwaymen and
wild animals was very prevalent. It is for this reason that these two
dangers are specifically mentioned in the text of tefilas haderech.
The question is, however, what is the status of our roadways? Very
often, even intercity roads traverse populated areas, thus minimizing
the original types of dangers mentioned in tefilas haderech. Does one
recite tefilas haderech if he travels on such a road?
The crux of the issue is: Did Chazal institute tefilas haderech only
because of those specifically mentioned dangers, or was it instituted
for other types of danger as well?
This is debated by contemporary poskim. The Chazon Ish zt”l maintains
that all types of dangers were included and since automobile travel is
dangerous, one recites tefilas haderech even if traveling intercity in
built up areas. HaRav Shlomo Zalman Auerbach zt”l, however, holds that
tefilas haderech was instituted only for the stated types of danger.
Hence on many of our roads, tefilas haderech is said without the
Of course, if the area of travel is known to be a dangerous place,
tefilas haderech is recited with the concluding bracha, as we
previously mentioned. (Sefer Ishei Yisrael chap. 50, footnote 24)
The term "travel" doesn't seem to be restricted to just by automobile. I'd be surprised if Chazon Ish and Rav Auerbach would nullify with Mishna Berurah and others have stated.