KUƊIN SHIGA MANHATTAN: ZIRGA-ZIRGA TA RAGU DA 42%?

Tun daga ƙarfe 12:01 na dare a ranar 5 ga Janairu 2025, kusan kowace mota da ke shiga Manhattan a kudancin 60th Street, har da titin kansa, tana biyan kuɗi. Ga mota $9 ne a lokutan cunkoso (ƙarfe 5 na safe zuwa 9 na dare a ranakun aiki, ƙarfe 9 na safe zuwa 9 na dare a ƙarshen mako) da $2.25 a sauran lokuta, sau ɗaya a rana, wajen shiga kawai. A cewar takardar, New York ita ce birnin Amurka na farko da ke gudanar da kuɗin shiga kewaye (cordon toll) na dindindin: kana biya don ƙetare wani layi da aka zana a kewayen wata unguwa.

Ra’ayin tattalin arzikin tsoho ne. Kowane direba yana rage gudun kowa ba tare da ya biya ba; kuɗin da ya yi daidai da wannan ɓoyayyen farashi yana sa direbobi su yi la’akari da shi. Stockholm, Milan, London da Singapore sun ga raguwar zirga-zirga ta kashi goma ko fiye bayan kuɗin hanyarsu, galibi a lokutan cunkoso: kusan 20% a Stockholm.

Titunan arewacin 60th a matsayin ma’auni

Yash Prajapati, a University of Kansas, yana amfani da wata hanya da ake kira difference-in-differences (bambancin bambance-bambance). Binciken yana kwatanta yadda zirga-zirga ta sauya a cikin yankin da yadda ta sauya, a cikin lokaci ɗaya, a titunan Manhattan da ke daidai arewacinsa, kusan tsakanin 60th da 110th Street: yanayi iri ɗaya, sufurin jama’a iri ɗaya, girgizar birni gaba ɗaya iri ɗaya, amma babu kuɗin hanya. Abin da ya shafi rukunonin biyu yana soke juna; abin da ya rage ana danganta shi ga kuɗin hanyar, muddin rukunonin biyu za su tafi tare ba tare da shi ba.

Ƙirge-ƙirgen sun fito ne daga na’urorin naɗar zirga-zirga na atomatik (automatic traffic recorders) na birnin, Janairu 2023 zuwa Fabrairu 2026. Samfurin kuma yana la’akari da zirga-zirgar da aka saba a kowane titi, kalanda, yanayi da ranakun hutu. Yana aiki ne a kan logarithm na zirga-zirga a kowace awa, ma’auni inda matakai daidai ke nufin sauye-sauyen kashi daidai; coefficient a wannan ma’auni ba kashi ba ne shi kansa, kuma marubucin yana juya shi da 1 − e^coefficient.

41.7%, a takarda

• Babban ƙiyasi: −0.539 a ma’aunin log, wanda marubucin ya juya zuwa raguwar motoci da kashi 41.7% a kowace awa a cikin yankin, idan aka kwatanta da titunan arewacinsa.
• Kafin kuɗin hanyar, titunan da aka ƙirga a cikin yankin suna ɗaukar motoci 1,447 a kowace awa a matsakaici: ƙiyasin yana nufin raguwar kusan 603 a kowace awa a kowanne.
• Matsakaitan ɗanye sun fi sauƙi: −15% a cikin yankin (1,447 zuwa 1,230), +4% a arewacin 60th Street (812 zuwa 842).
• Raguwar ta fi girma a lokutan farashin cunkoso (−0.484 a ma’aunin log) fiye da sauran lokuta (−0.314), kamar yadda ka’ida ta yi hasashe (kuɗin lokacin cunkoso ninki huɗu ne na na sauran lokuta), duk da cewa babu ɗayan waɗannan lambobi da ke da ma’ana a ƙididdiga (statistically significant) (wato, bayyananne har ya kawar da yiwuwar sa’a).
• Idan aka ƙirga a motoci maimakon logs, kwatancen iri ɗaya yana ba da motoci −107 a kowace awa kawai a kowane sashe (p = 0.08), ƙasa da 603 na sama da fiye da ninki biyar, giɓin da takardar ba ta bayyana ba. Alamar tana ci gaba da zama korau a kowane gwajin ƙarfi (robustness check).

Marubucin ya lura cewa 41.7% kusan ninki biyu ne na lambar Stockholm, kuma hakan “yana buƙatar taka-tsantsan”.

Sassan hanya uku da gefe mai faɗi

Na’urorin naɗar birnin suna motsawa daga wuri zuwa wuri, don haka duk da cewa ƙirgen ya fara a Janairu 2023, samfurin yana riƙe ne kawai na’urorin ƙirga da aka lura da su na aƙalla awa 48 duka kafin da bayan kuɗin hanyar. A cikin yankin, hakan ya bar sassan hanya uku: East 58th Street da hanyoyi biyu na hanyar shiga Williamsburg Bridge, da awa 360 kawai (kwanaki 15) na ƙirge kafin kuɗin hanyar da 216 (kwanaki 9) bayansa.

Rashin tabbas ɗin yana da girma. Babban ƙiyasin yana da p-value na 0.24: idan kuɗin hanyar bai yi komai ba, ƙiyasi mai nisa haka daga sifili zai bayyana kusan sau ɗaya cikin huɗu. Tazarar amincewa (confidence interval) ta 95% (kewayon ƙimomin da suka dace da bayanan), daga −1.44 zuwa +0.36 a ma’aunin log, ta haɗa da sifili har ma da ƙimomi tabbatattu: ƙarin zirga-zirga. Marubucin ya kira sakamakon “mai daidaito a alƙibla” (direction-consistent) amma “mara isasshen ƙarfin ƙididdiga” (statistically underpowered), kuma ya ɗora laifin a kan ƙarancin na’urorin ƙirga maimakon ƙaramin tasiri.

Gwaje-gwaje biyu suna ƙara shakka. A yi kamar kuɗin hanyar ya fara shekara ɗaya kafin haka, a ranar 5 ga Janairu 2024, kuma samfurin har yanzu yana samun ƙiyasi korau (−1.03, mara ma’ana a ƙididdiga). Marubucin ya kira shi “tutar rawaya” (yellow flag): wani ɓangare na raguwar na iya fitowa daga sauye-sauye a cikin na’urorin ƙirga da ke aiki, ba daga kuɗin hanyar ba. Kuma gwajin mako-mako na cewa rukunonin biyu sun tafi tare ya dogara ne kan makonni 9 kawai kafin kuɗin hanyar. Awa bayan awa, hoton ma yana da dishi-dishi haka.

Tasirin da aka ƙiyasta na kuɗin hanyar awa bayan awa, a ma’aunin log: tabbatacce daga ƙarfe 6 zuwa 9 na safe, korau daga ƙarfe 10 na safe har zuwa maraice, kuma kowace tazarar 95% (sanduna a tsaye) tana ƙetare sifili. — Figure 4, Prajapati (2026), arXiv:2610.34818.

Zirga-zirgar da wataƙila ta zagaya

A kan gadojin da ke cikin samfurin, zirga-zirga ta ƙaru da 25% bayan kuɗin hanyar ya fara (+0.227 a ma’aunin log, p = 0.036), ɗaya daga cikin ’yan sakamakon binciken masu ma’ana a ƙididdiga. A arewacin 60th Street, sauyin kusan sifili ne. Marubucin yana ganin hakan ya dace da direbobi suna sauya hanyoyi, amma rukunin ya haɗa hanyoyin shiga Williamsburg Bridge, a cikin yankin, da gadoji biyu da ke haɗa Manhattan a arewacin 60th Street da Bronx: shi kaɗai, ba zai iya nuna dalilin da yasa zirga-zirga ta ƙaru ba.

Shiga miliyan 4.86, duka bayan farawa

Na’urorin karɓar kuɗin hanya sun fi yawa nesa ba kusa ba: bayanan minti goma miliyan 4.86 na shiga cikin yankin, 5 ga Janairu 2025 zuwa 18 ga Afrilu 2026. A ranakun aiki, shigowa tana hawa da ƙarfi zuwa kololuwar safe kusan ƙarfe 8 na safe, sannan ta riƙe wani faffaɗan tudu (plateau) har zuwa la’asar; a ƙarshen mako tana hawa a hankali zuwa wani tudu a tsakiyar la’asar. Marubucin ya danganta wannan lokacin cunkoso da ya yi lebur da dogon lokacin farashin cunkoso na awa 16.

Matsakaicin shigowa cikin yankin a kowace awa bayan kuɗin hanyar ya fara, a ranakun aiki (shuɗi) da a ƙarshen mako (ruwan lemu), matsakaici a duk wuraren ganowa da nau’o’in motoci; ratsin launin toka yana nuna lokutan farashin cunkoso na ranakun aiki. — Figure 7, Prajapati (2026), arXiv:2610.34818.

Waɗannan bayanai sun fara ne a ranar da kuɗin hanyar ya fara. Suna nuna yadda ake amfani da yankin yanzu, ba yawan zirga-zirgar da ya rasa ba.